earth, energy and all forms of events in it are in the process of fundamental change in the environment of his universe AMNIMARJESLOW AL DO FOUR DO AL ONE LJBUSAF thankyume

                                                                    X  .  I

                                     How is water treated for use in homes? 
         
 

All over the world, fresh water is treated differently at a treatment center before it is sent to your home. Surface water is more often treated rigorously than underground water, as it has less contaminants.

The diagram below show a basic water treatment process for surface water.
 

 
  * Caoguation stage :Alum and other chemicals are added to the water at this stage. Suspended particles get stuck to the chemicals to form 'floc'.

Sedimentation Stage:
As particles get stuck they become heavy and sink to the bottom of the chamber. At this stage, most of the particles are stuck to form sediments, sinking to the bottom. The water is passed onto the Filtration chamber.

Filtration stage:
As water passes slowly through this chamber, finer particles (sediments) are filtered out over layers of sand, charcoal and gravel.

Disinfection stage:
Chlorine or other kinds of disinfection methods is applied to kill any bacteria and other living organisms that may be in the water. It is very normal and natural for fresh water to contain living organisms.

Storage stage
The water is then passed into large storage tanks and left for a while for the action of disinfection to be complete. At the tail end of this storage tanks, huge pipes are connected to transport water to our homes and work places. 

Causes of water scarcity

Here are some important causes of water shortage:

Population expansion
Just 50 years ago, the total number of people on earth has doubled and continues to grow. This is a result of larger family sizes and access to better health care and lifestyles. This means that use of wholesome water for drinking, cleaning, cooking and sewage has tripled. Humans are a lot more careless in recent time, and we waste more water than ever before. This has placed a lot of pressure on the same amount of water that we have.

Urbanisation
Cities are growing and expanding more than ever before. Cities also tend to hold more people than towns and villages. This means there an increased need to take care of sewage, cleaning, construction and manufacturing. 

  

Water, air and land pollution together contribute to the reduction of water quality. Sewage, oil discharges from industries, waste dumping into water bodies, radioactive waste from mining activities as well as dirty water fro sanitation work in hospitals, hotels, oil companies, mining, schools and restaurants all end up polluting our waters. Water contamination and wastage from some mining industries through Hydraulic Fracturing (fracking) has also been a worry for many people. Vegetation destruction and Deforestation
Trees help prevent excessive evaporation or water bodies. They also enrich and condition the climate. This means the destruction of  forests by fire, logging and farming has exposed soil moisture and water bodies to the sun’s intense heat, leaving them dried out.

Climate change
All over the world, places that used to have lots of rainfall do not have enough again and dry places suddenly are getting colder and wetter. Both cases result in clean water shortage because less rainfall means less water, and excessive rains cause flooding and which brings all sorts of debris and destroy water treatment  

installation . 

What are the effects of water shortages?

The effects of water scarcity can be grouped into these 4 broad areas— Health, Hunger, Education and Poverty.

Health
In many developing countries, people are forced to drink low quality water from flowing streams, many of which are contaminated. There are many water-borne disease that
people die of.

Less water also means sewage does not flow, and mosquitoes are other insects breed on still (stagnant) dirty water. The result is the deadly malaria and other infections.
Lack of water or quality water causes huge sanitation issues. Clinics, local restaurants, public places of convenience and many other places are forced to use very little water for cleaning. This compromises the health of the staff and people who use the facilities.

Hunger
It takes a lot of water to grow food and care for animals. Experts say that globally we use 70% of our water sources for agriculture and irrigation, and only 10% on domestic uses.
Less water means farming and other crops that need water to grow have lower yield. It means farm animals will die and others will not do well without water. The result is constant hunger and thirst and low quality of life. 

Education
It is a bit hard to see how water and education is related. For many people in other parts of the world children (and teen girls) have to be up at dawn to collect water for the family. They have to walk for several miles to get water. The children get tired and some have to miss school as a result. Doing this for many years take away school times and the cycle continues. In other places girls and women are not allowed to go to school at all, so that they can serve the family by getting water and and taking care of other family needs.

Poverty
Access to quality water is key to economic prosperity and better living standards. Businesses and schools thrive when people come to work on time and not have to spend all morning looking for water. Restaurants, hotels and shopping places need to keep clean to attract tourists and foreign investments. Manufacturing activities, commercial farms, and mining processes all need a lot of water to thrive. Lack of water means no economic activities will happen and the people will be in constant poverty. 


What is your role in water preservation?

Sometimes the magnitude of a problem can make one feel that there is nothing that can be done. But there is a lot you can do for water. There is a high chance that people reading this do not live in water deprived areas, and may think it is not their problem. Here is what you can do to help.

Awareness
Learn about water crisis, just like you are doing. If you understand a problem, you are in a better position to have a solution. Talk about it with family and friends. Look out for news and facts on water shortages and crisis areas.

Take part
Be part of competitions, organizations and societies that aim to preserve and defend natural resources including water. Speak to you parents about donating or helping out charity grouped to provide water to the most needy places.

Use water wisely
Never assume that your society is too advanced to experience water shortage. If we do not acquire the right attitude towards water, it is only a matter of time and one day there will be a shortage. Keep the tap off when not in use. Minimize the flushing of toilets and bath times. In effect, anything that you can do to save water, do it.

Industries and Governments
Join pressure groups that stop individuals, industries and governments from cutting down trees and doing other things that pollute and degrade the environment.

Water scarcity fact sheet

Agriculture

Agriculture is by far the biggest user of water, accounting for almost 70 percent of all withdrawals, and up to 95 % in developing countries.

The water needed for crops amounts to 1000-3000 cubic meter per tonne of cereal harvested. Put another way, it takes 1—3 tonnes of water to grown 1kg of cereal.

The daily drinking-water requirements per person are 2-4 litres. However, it takes 2000—5000 litres of water to produce a person's daily food.
Between now and 2030, the world's population is expected to grow by 2 billion people. Feeding this growing population and reducing hunger will only be possible if agricultural yields can be increased significantly and sustainably.

With so much of the Earth's water being used for agriculture, it is clear that an improvement in the management of agricultural water becomes key to the achievement of global food security.

Water
One out of every three people is affected by water scarcity. Water researchers believe that the problem is getting worse with urbanization, population growth, industrialization and competitive commercial activities.

Almost one fifth of the world's population (about 1.2 billion people) live in areas where the water is physically scarce. One quarter of the global population also live in developing countries that face water shortages due to a lack of infrastructure to fetch water from rivers and aquifers .

In many poor and rural communities, people use waste-water to water their crops and farms because there is water shortage or scarcity. It is believed that 10% of all the foods we eat come from crops cultivated by wastewater. These can contain chemicals or disease-causing organisms.

What makes up Fresh Water?

In simple terms, fresh water is water that has little or no dissolved salts and dissolved solids. This excludes sea or marine waters and brackish water. All over the world, water comes in other forms such as ice-sheets, glaciers, lakes, ponds, rivers, streams and icebergs. The quantities found in every geographic area may vary.



Fresh water may be still or fast flowing. Still fresh water is known as ‘Lentic systems’ whiles flowing fresh water is known as ‘Lotic Systems’. Others come from underground as ground water in aquifers and underground streams.

Where does all fresh water come from? 
 
Fresh water comes from precipitation from the atmosphere, usually in the form of rain, mist and snow. When these fall, they find their way into streams and rivers which run down from mountain tops to low-lying areas. Eventually, they end up in the sea or ocean. Because much of atmospheric water end up falling into our water bodies, it is important that we keep an eye on the chemicals that find their way into the atmosphere via air pollution.

But how does water end up in the atmosphere in the first place? This can be explained in a model called The Water Cycle. 

The Water Cycle

Water is a renewable resource. Its' Cycle (also known as the hydrologic cycle) is simply the journey water takes as it circulates from the land to the atmosphere and back again.

With the help of the diagram below, let us see how the cycle works:

Let us start this cycle with precipitation. This is water that start as tiny water droplets, and become larger drops that fall from the sky (atmosphere) in the form of snow, rain and due.

Precipitation creates run-off, which adds to flowing water and end up in rivers, streams, lakes, lagoons and seas.

Some of the water also percolates (seeps through the soil) and into underground water.

The collected surface water then evaporates (turns into gas) and ends up as water vapour in the atmosphere. Condensation occurs and the water vapour it turned into rain-bearing clouds. In addition to that, plants absorb moisture, which also evaporates from the leaves into the atmosphere. This means there is more evaporation in regions with more water bodies and massive vegetation and tend to have more rain bearing clouds.

Rain bearing clouds then release the water in the form of precipitation and the cycle begins again. 






                                                              X  .  II  
                                                  CLIMATE  CHANGE 


Introduction to Climate change

Many people make Climate Change and Global Warming a scary and difficult thing to understand, but it’s not.


Scientists have warned that the world's climate has changed a lot, and has affected many living and non-living things.

Many places that were warmer are now getting colder, and many colder regions are getting much colder or even warmer (know as Global Warming).

For example, between 1901 and 2012, it is believed that the earth's temperature has risen by 0.89 °C. Rainfall amounts have also risen in the mid-latitudes of the northern hemisphere since the beginning of the 20th Century. It is also believed that sea levels have risen up to about 19cm globally, with lots of glaciers melting in addition.

Some people do not believe that these are caused by human activities. They think it is all political and falsehood intended to cause panic among humans.

Well, whatever it is, we would like to know more, and take a few good points from this confusion, and use them to make our world a better place to live.


Important Climate Change Terms

Climate
This describes the total of all weather occurring over a period of years in a given place. It is the average weather condition of that place. Climate tells us what it’s usually like in the place where you live.

For example, some countries like Cameroon, Ghana and Liberia are all in the tropical wet region of Africa. They have a very sunny, hot and wet climate all year round. However, there may be very different day-to-day weather conditions in each village or town in these countries.

Weather
Weather is all around us. Weather may be one of the first things you notice when you wake up. Weather describes whatever is happening outdoors in a given place at a given time. It can change a lot within a very short time. For example, It can be windy at night, rainy in the morning, hot and sunny at noontime, and even back to windy before sunset. It includes daily changes in rainfall, temperature and wind in a given location.

Greenhouse
Greenhouse is also another word you should know about. Have you ever seen a greenhouse? In some countries, people build a small glass house to plant crops in it. It is built to keep the sun's heat from escaping from the glasshouses.

In a way, the earth is like a glasshouse. The earth has some very important gasses in the atmosphere that keeps us warm.

Some of these gases are water vapour, carbon dioxide, nitrous oxide and methane.

When the sun heats the earth, these gases keep the heat on the earth's surface. Without these gases, heat would escape back into space and Earth’s average temperature would be about 60°F colder.


  How does the Greenhouse Effect happen?




The earth’s atmosphere is all around us.
It is the air that we breathe.



Sunlight enters the Earth’s atmosphere,
passing through the blanket of greenhouse gases.



As it reaches the earth’s surface, the land
and water absorbs the sunlight’s energy.



Once absorbed, the energy is sent back into the
atmosphere in the form of infra-red rays.



Some of the energy passes back into space, but much of it remains trapped in the atmosphere by the greenhouse gases, causing our globe (earth) to warm up.



This warming is what we call Global Warming, and it is caused by the greenhouse effect.

The greenhouse effect is important. Without the greenhouse effect, the earth would not be warm enough for humans to live. But if the greenhouse effect becomes stronger, it could make the earth warmer than usual. Even a little extra warming of the earth may cause problems for humans, plants and animals.


What brings about more Greenhouse gases?

In this new era (the age of industrialization), the earth is full of industries. Millions of vehicles, aeroplanes and engines are produced every year. A lot of artificial things have been produced and have ended up in waste dumps. Humans produce much more waste than ever before.

Take a good look at the simple sketch below.

What did you notice in that sketch? What do all those activities have in common?

They all produce a lot of smoke, fumes and water vapor!

Energy production is still a major driver of GHG (greenhouse gas) emissions. For instance, in 2010, the energy sector emitted approximately 35% of GHG, followed by Agriculture, forests and other land uses (24%), Industry (21%), Transport (14%) and Building sector (6.4%)

Simply put, human's reliance on artificial things, including all the things that make us comfortable at home, has contributed immensely to the emission of more greenhouse gases than before. These gases in the atmosphere have trapped more heat on the earth’s surface and made it warmer. This is Global Warming.

YOU and I also produce and other greenhouse gases in a way, by the things we use at home. Do you have some of these items in your house?
It is very IMPORTANT that you turn off all electrical appliances when they are not in use. This is good practice, and you end up saving some money too.

Everything humans have at home or workplace need power to work. This power comes from burning fossil fuels and other natural sources. The more fuels are burnt, the more are produced into the atmosphere.
This means each time your dad drives his car, or you turn on an electric appliance, you are indirectly adding to the greenhouse gases in the atmosphere.

But thats not all — it must also be noted that less forest cover all over the world has resulted in less carbon absorption and storage. This is because plants absorb carbon from the atmosphere during photosynthesis. Additionally, there is more methane release from permafrost due to higher temperatures.

This is not very good, as we are all contributing to global warming and climate change. This is a problem.

In recent time, some coal industries are finding ways to capture emissions and storing them deep under the seabed. This move is called Carbon Capture and Storage.

Effects of Climate change
Let’s see these 4 good effects.

Global warming causes thermal expansion of land and water. It also causes ice sheets to melt in icy regions of the world and mountain tops.
Large volumes of melted ice (water) then flow down into streams, rivers, lakes and seas. The result is rising sea and water levels, causing floods and massive destruction to low-lying towns and cities along water bodies. More on risisng sea levels here

Research shows that global sea level rose about 17 centimeters (6.7 inches) in the last century, and the rate in the last decade is nearly double that of the last century. —Source: climate.nasa.gov
Changing climate may also cause the weather to become more extreme, be it droughts or violent storms and heavy rain.



Extreme changes in temperature makes people suffer breathing difficulties, head aches, body rashes and other illnesses.

Climate change also distorts the natural habitats and lives of many plants and animals. For example, the survival of polar bears and penguins in icy regions are in danger, as they cannot survive anywhere else. Other plants and animals in hot regions will die if temperatures suddenly become too cold for them.

Did you know...
The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic kilometers (36 to 60 cubic miles) of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometers (36 cubic miles) of ice between 2002 and 2005. —Source: climate.nasa.gov


The same amount of water in the water cycle will not be affected, but its timing, amounts, regularity and distribution will be impacted. Mid- latitudes and dry subtropical regions may experience a reduction in water flow, whiles high latitudes and humid mid-latitude regions may have increased water flow. There may be streamflow uncertainty in many other regions, because of reduced snow and ice storage. Availability of clean water may be affected too, for instance, the quality of lakes used for water supply could be impaired by the presence of algae producing toxins .

 Interesting facts on climate change

Rising global temperatures
A rising trend in global temperatures has been noticed after analyzing data for the last century. Scientists are aware that the difference in temperatures around the world is very wide apart, but after taking readings at specific locations over a long period of time, it is observed that there are more places warming up than cooling down.

From 1900-2009, global average surface temperatures rose by approximately 0.7°C (1.3°F). It has also been noted that the rate of increase has risen in recent time.


Carbon Dioxide ()
Humans burning coal, natural gas and oils for manufacturing and transportation, since the Industrial Revolution, has produced and released massive carbon dioxide and other greenhouse gases into the atmosphere.

To put this in perspective, about 38% more has been released into the atmosphere, a value higher than has been measured for over 800,000 years. And yes, the amounts we release is still rising year after year.
The acidity of the earth's oceans is known to have increased by about 30%. This is a result of more emitted since the Industrial Revolution, being absorbed by the oceans. being absorbed by the upper layer of the oceans is increasing by about 2 billion tons per year .
Glaciers are massive amounts of snow that have stayed long enough to harden into blocks of ice. Smaller blocks could be the size of a football field and larger once could be hundreds of kilometers long. Glaciers can move like rivers too. On the average, glaciers are losing ice at the rate of about 28 inches of water per year. Scientists revealed that even though only a small fraction of glaciers have been monitored since 1980, the trend is one that we need to be aware of.

Which regions of the world are producing more ?



In December 2014, Nasa's Orbiting Carbon Observatory (OCO-2) released its first map of the Earth's surface where carbon dioxide is being emitted and absorbed. Even though the mission is in its early stages, the data will help scientists to better understand how human activities affects climate.
Things you can do about global warming.

Before we look at what you can do, it is important to note that big automobile industries, refineries, commercial farmers, and others are the main bodies with the highest carbon emissions. This is because we rely on them to provide products and food that we enjoy at home. This means if we reduce our reliance for these big industries, they won't have to produce more.

So, a good way to solve the problem may be from our government and legislature level to regulate these big companies. We can get our leaders to make laws that discourage activities that have a high carbon footprint.

Did you know... Energy production and consumption contribute greatly to emissions. This means improving energy efficiency will reduce global emissions. In modern times, new energy efficient buildings use 60–90% less energy than conventional buildings of a similar type and configuration.

But many of our leaders have been a bit disappointing. So it is our turn to do our bit!

What about you? ...in your own little way?
Start by reducing your carbon footprint. Your carbon footprint is the sum of all emissions of CO2 (carbon dioxide), which were produced by your activities in a given time frame.

Let's start with vehicles. Vehicles produce greenhouse gases.

Go by bus!
Get your family to go to school, work, market, holiday, place of worship on a bus rather than in daddy’s car. It’s cheaper too, and you save some money.

Walk! Don’t drive.
Walk to the shop, market, farm, school and everywhere. Sometimes there are too many cars causing heavy traffic and it is better to walk. It is also great exercise.

Ride! Don’t drive.
You can always ride down to almost everywhere. It's great fun and very good exercise!

Protect and plant trees.
Planting trees is a fun and great way to reduce greenhouse gases. Trees absorb CO2, (a greenhouse gas) from the air. This means the air will be fresher and also help regulate climate. You can also save old trees by protecting them from being cut down. One great way to have fun with trees is to plant one on every special day like your birthday, Christmas, National holidays or even in memory of special friends.


Recycle, reduce and re-use items.
Recycling, reducing the use of things and re-using things is also a brilliant attitude for us to acquire. When we recycle cans, bottles, plastic and paper, we send less trash to a landfill. It also helps save natural resources such as trees, oil and aluminum.

When you go shopping, always look for the recycle mark on products before buying them. The mark means they have been produced from recycled materials, and you want to encourage them to do so.

If your community does not have recycling services with waste collection, this is the time to join a group to talk about it.

In recent time, some coal industries are finding ways to capture CO2 emissions and storing them deep under the sea bed. This move is called Carbon Capture and Storage 



                                                                       X  . III
                                               RENEWABLE  ENERGY SOURCES

What is renewable energy?

Energy exists freely in nature. Some of them exist infinitely (never run out, called RENEWABLE), the rest have finite amounts (they took millions of years to form, and will run out one day, called NON-RENEWABLE)

With this in mind, it is a lot easier to lay any type of energy source in its right place. Let's look at these types of energy in the diagram below:

You will notice that water, wind, sun and biomass (vegetation) are all available naturally and were not formed. The others do not exist by themselves, they were formed. Renewable energy resources are always available to be tapped, and will not run out. This is why some people call it Green Energy.

TIP
Approximately 20% of electricity produced globally in 2009 came from renewable sources. Out of this, hydro-power accounted for about 16%.

In 2012, 9% of the energy consumed in the USA came from renewable sources. This means the USA depends a lot on non-renewable sources. 30% of the energy from renewable sources came from hydropower, whiles biomass, biofuels and wood, together accounted for about 49%.


Illustration of Global Renewable Energy Usage.

When can energy be called 'Renewable'?
When its source cannot run out (like the sun) or can easily be replaced (like wood, as we can plant trees to use for energy)
When their sources are carbon neutral. This means they do not produce Carbon compounds (such as other greenhouse gases).
When they do not pollute the environment (air, land or water)

Renewable energy includes Biomass, Wind, Hydro-power, Geothermal and Solar sources. Renewable energy can be converted to electricity, which is stored and transported to our homes for use. In this lesson, we shall take a closer look at how renewable energy is converted into electricity .

What is Biomass

Biomass fuels come from things that once lived: wood products, dried vegetation, crop residues, aquatic plants and even garbage. It is known as 'Natural Material'. Plants used up a lot of the sun's energy to make their own food (photosynthesis). They stored the foods in the plants in the form of chemical energy. As the plants died, the energy is trapped in the residue. This trapped energy is usually released by burning and can be converted into biomass energy.

Wood is a biomass fuel. It is renewable. As long as we continue to plant new trees to replace those that were cut down, we will always have wood to burn. Just as with the fossil fuels, the energy stored in biomass fuels came originally from the Sun.

It is such a widely utilized source of energy, probably due to its low cost and indigenous nature, that it accounts for almost 15% of the world's total energy supply and as much as 35% in developing countries, mostly for cooking and heating.
How is biomass converted into energy?
Burning:
This is a very common way of converting organic matter into energy. Burning stuff like wood, waste and other plant matter releases stored chemical energy in the form of heat, which can be used to turn shafts to produce electricity. Let's see this simple illustration of how biomass is used to generate electricity.


1. Energy from the sun is transferred and stored in plants. When the plants are cut or die, wood chips, straw and other plant matter is delivered to the bunker

2. This is burned to heat water in a boiler to release heat energy (steam).

3. The energy/power from the steam is directed to turbines with pipes

4. The steam turns a number of blades in the turbine and generators, which are made of coils and magnets.

5. The charged magnetic fields produce electricity, which is sent to homes by cables.

Other ways in which organic matter can be converted into energy include:

Decomposition:
Things that can rot, like garbage, human and animal waste, dead animals and the like can be left to rot, releasing a gas called biogas (also known as methane gas or landfill gas). Methane can be captured by a machine called Microturbine and converted into electricity. Sometimes, animal waste (poop) can also be converted into methane by a machine called 'Anaerobic Digester'
Fermentation:
Ethanol can be produced from crops with lots of sugars, like corn and sugarcane. The process used to produce ethanol is called gasification.

What is Wind Power?

Wind is caused by huge convection currents in the Earth's atmosphere, driven by heat energy from the Sun. This means as long as the sun shines, there will be wind.

How do winds form?
This can be explained in simple terms by the daily wind cycle.



The earth's surface has both land and water. When the sun comes up, the air over the land heats up quicker than that over water. The heated air is lighter and it rises. The cooler air is denser and it falls and replaced the air over the land. In the night, the reverse happens. Air over the water is warmer and rises and is replaced by cooler air from land.

The moving air (wind) has huge amounts of kinetic energy, and this can be transferred into electrical energy using wind turbines. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. The electricity is sent through transmission and distribution lines to a substation, then on to homes, business and schools.

Wind turbines cannot work if there is no wind,
or if the wind speed is so high it would damage them.


Wind turbines are usually sited on high hills and mountain ridges to take advantage of the prevailing winds.

Just like a windmill, wind energy turbines have been around for over 1000 years. From old Holland to farms in the United States, windmills have been used for pumping water or grinding grain. 

Did you know...
The largest wind turbine in the world, located in Hawaii,
stands 20 stories tall and has blades the length of a football field.

An average wind speed of 14 miles per hour is needed to
convert wind energy into electricity.

One wind turbine can produce enough electricity to power up to 300 homes.

The first power-generating turbine was constructed in
Ohio during the late 1800's and was used to charge batteries.

Wind energy is the fastest growing segment of all renewable energy sources.

In 2013, about, 7.9% (28.4 TWh) of electricity generated in the UK, for example, came from wind turbines. That amount is enough to power 6.8million homes. The cost of installing wind energy technology is known upfront, so future prices will be more stable than energy from coal or gas because those are imported and the prices change very often. 

Water power

Moving water has kinetic energy. This can be transferred into useful energy in different ways. Hydroelectric power (HEP) schemes store water high up in dams. The water has gravitational potential energy which is released when it falls.

Let's see a good example of how water can be used to generate electricity.



As the water rushes down through pipes, this stored energy is transferred to kinetic energy, which turns electricity generators.

The Dam is built to retain the water. More electricity is produced if the water is more in the reservoir

Sluice Gates: These can open and close to regulate the amount of water that is released into the pipes.

Potential energy in the retained water is transferred into kinetic energy by water flowing through the pipes with high speed.

The force and high pressure in the water turns a series of shafts in a generator. Spinning shafts in the generator charges millions of coils and magnets to create electricity, which is regulated by a transformer. This is then transported via cables to homes and factories.

To build a dam there has to be valleys and rivers that flow all year round. This will help with the building and success of the dam. This way, the fullest effect of the waters kinetic energy can be tapped.


Global Distribution of Hydro-Power Generation Capacity.

Did you know...

Hydropower is a renewable energy source that doesn't cause global warming because it doesn't release dangerous greenhouse gases.
China is the largest producer of hydroelectricity, followed by Canada, Brazil, and the United States (Source: Energy Information Administration).
Hydropower is the most important and widely-used
renewable source of energy.

Geothermal energy

Deep down in the earth's crust, there is molten rock (magma). Molten rock is simply rocks that have melted into liquid form as a result of extreme heat under the earth. This can be found about 1800 miles deep below the surface, but closer to the surface, the rocks layers are hot enough to keep water and air spaces there at a temperature of about 50-60 degrees F (10-16 degrees C). Geothermal technology takes advantage of the hot close-to-earth-surface temperatures to generate power.

In places with hotter 'close-to-earth-surface' temperatures, deep wells can be drilled and cold water pumped down. The water runs through fractures in the rocks and is heated up. It returns to the surface as hot water and steam, where its energy can be used to drive turbines and electricity generators. (Note that there isn't any technology that allows humans to tap the heat from molten rock yet. Maybe one day, there will be)



In other places, a geothermal heat pump system consisting of pipes and pumps buried in the earth can be used to heat homes. This is done by opening up the system, extracting the hot air to feed indoor air delivery system during the cold seasons. In the USA, some geothermal systems can be found in Hawaii and Alaska. Geothermal energy is called a renewable energy source because the water is replenished by rainfall, and the heat is continuously produced by the earth.

Solar power

Solar power is energy from the sun. "Solar" is the Latin word for "sun" and it's a powerful source of energy. Without it, there will be no life. Solar energy is considered as a serious source of energy for many years because of the vast amounts of energy that is made freely available, if harnessed by modern technology.

It is renewable!
It is considered 'Renewable Energy' because...
The technology used to convert the sun's power into electricity does not produce smoke (carbon dioxide and other air pollutants).
Tapping the sun's energy does not usually destroy the environment.
Unfortunately, the sun does not available in the night, and in some days, clouds and rains and other natural conditions prevent the sun's powerful rays from reaching us. This means that it is not always available. This a why we cannot rely on solar energy alone.
Solar cells
Solar cells are devices that convert light energy directly into electrical energy. In these cells, there are semiconductors (silicon alloys and other materials). You may have seen small solar cells on calculators or some mobile phones. Larger arrays of solar cells are used to power road signs, and even larger arrays are used to power satellites in orbit around Earth. Solar cells are also called photovoltaic cells or PV devices.
Solar panels
Solar panels are different to solar cells. Solar panels do not generate electricity directly. Instead they heat up water directly. A pump pushes cold water from a storage tank through pipes in the solar panel. The water is heated by heat energy from the Sun and returns to the tank. They are often located on the roofs of buildings where they can receive the most sunlight.

There is also the Solar Thermal Power Plant. Here, a concentration of the sun's energy by many panels is used to heat up water into steam, which is then used to turn turbines to produce electricity.

Guess what! Power stations of this nature usually need a lot of space to capture a lot of the sun's energy!

The Parabolic Trough System uses this kind of system. Here, troughs are designed to direct the sun's energy to absorber tubes as long as the sun is up.

Many of these Parabolic troughs are installed to collect massive energy for the rods to heat water to turn turbines.


Other less common methods that use the Solar Thermal Power Plant system are the Solar Dish and The Solar Power Tower.


Marine (Ocean) Energy

The oceans have an incredible amount of power and energy potential. Even though the marine energy technology has not fully delivered on its potential, there has been, in recent time, a number of areas in marine energy that has kicked off. The UK is believed to be a leading player in Marine energy. Even though its capacity presently is only about 9megawatts, it is on course to deliver about 120MW by 2020. Two of these are Wave energy and Tidal Energy.

Wave Energy: How does it work?
Wave energy (WE) harnesses the kinetic energy in the up-and-down movement (waves) of water in the ocean. The waves are caused by wind action, and wind action is caused by the sun heating the surface of the waters, generating air pressure. This means as long as there is the sun, there will be wind and waves, even though its intensity may vary.

WE locations are best where there are strong winds traveling over very long distances. This makes places like the west coast of UK a great point, because of the winds over the Atlantic.

Wave Energy is captured by devices called Wave Energy Devices. There are several types of Wave Energy Conversion devices including the following:



A. Point Absorber: This floating structure moves up and down and in all directions. With some conversion mechanisms inside it, power is converted and stored in a hub at the base.

B. The Attenuator: This floating device also rides the waves, flapping like the wings of a bird, a movement caused by the pounding waves. The kinetic energy in the movement is converted into energy and stored.

C. The Oscillating Wave Surge Converter: This device extracts energy from the waves of the water. It is installed below the water surface, but the current is strong enough to cause it to oscillate.

How does Tidal Energy work?
Ocean tides are caused by the earth’s rotation, as well as the combined gravitational fields of the earth, sun and the moon. This combination shapes the gravitational pull on the earth’s oceans. The oceans tidal stream is even more powerful when wind air pressure systems get involved. Areas with greater current speeds, narrow straits and inlets, as well as channels between islands are perfect locations for installing tidal energy structures.

Some tidal structures (or devices) look a lot like wind energy blades, but this time, installed under water to harness the kinetic energy in the oceans currents. Unlike in wind turbines, the blades in tidal energy devices move a lot slower because of the high density of the medium (water). However, they carry a lot of power.

Some tidal converters work just like the wind turbines. Kinetic energy from the spinning of the blades, caused by the currents is tapped with the help of some converters inside of the spinning structures to generate electricity.

Examples of tidal energy converters include the Horizontal Axis Turbine, Vertical Axis Turbine and the Oscillating Hydrofoil.

The world’s biggest Tidal Power Plant is the Sihwa Lake Tidal Power Station in South Korea, with 254MW output capacity. There is also a 240MW output capacity plant in France called La Rance Tidal Power Plant.

What are the problems with Marine Energy?
Marine energy comes with its own problems and challenges.
For example, the unpredictable changes in wave patterns (extreme tides to very calm waters can cause huge structural damage.

It can also cause overload operation problems. There is also the lack of data and information on this new area, and many governments and businesses are less encouraged to jump on board.

Then there is also the environmental concern such as marine energy facilities may affect wave hydrodynamics, create artificial habitats, concerns with marine animals, noise and so on.




                                                                 X  .  IIII
                                              NON RENEWABLE ENERGY 


What is non-renewable energy?

Energy exists freely in nature. Some of them exist infinitely (never run out, called RENEWABLE), the rest have finite amounts (they took millions of years to form, and will run out one day, called NON-RENEWABLE).

Non-renewable energy is energy from fossil fuels (coal, crude oil, natural gas) and uranium. Fossil fuels are mainly made up of Carbon. It is believed that fossil fuels were formed over 300 million years ago when the earth was a lot different in its landscape. It had swampy forests and very shallow seas. This time is referred to as 'Carboniferous Period'

Fossil fuels are usually found in one location as their formation is from a similar process. Let us take a look at the diagram below to see how fossil fuels are formed:





1. Millions of years ago, dead sea organisms, plants and animals settled on the ocean floor and in the porous rocks. This organic matter had stored energy in them as they used the sun's energy to prepare foods (proteins) for themselves (photosynthesis).

2. With time, sand, sediments and impermeable rock settled on the organic matter, trapping its' energy within the porous rocks. That formed pockets of coal, oil and natural gas.

3. Earth movements and rock shifts create spaces that force to collect these energy types into well-defined areas. With the help of technology, engineers are able to drill down into the seabed to tap the stored energy, which we commonly know as crude oil.

The good thing is about fossil fuels is:
Unlike many renewable sources of energy, fossil fuels are relatively less expensive to produce. This is probably why it is in higher demand as it tend to cost less.

The bad thing about fossil fuels is:
Fossil fuels are made up mainly of carbon. When they are burned (used) they produce a lot of carbon compounds (carbon dioxide and other greenhouse gases) that hurt the environment in many ways. Air, water and land pollution are all consequences of using fossil fuels.

In the pages that follow, we shall take a look at what each source of non-renewable energy is made of, and how they are used.

Note that not all non-renewable energy comes from fossil fuels. There is also uranium, which is not a fossil fuel.

 What is coal? Coal is a combustible black or brownish-black sedimentary rock composed mostly of carbon and hydrocarbons.
Coal is made of the remains of ancient trees and plants that grew in great swampy jungles in warm, moist climates hundreds of millions of years ago. The chemical and organic process these dead organisms undergo to become coal is known as Carbonization. Coal is ranked very high if it has undergone a longer carbonization period. An example is Anthracite. Coal that has not undergone too much carbonization is ranked low, and an example is Peat.

How is coal converted into electricity?

Let us take a look at the diagram below:




1. Coal is milled to a fine powder, allowing it to burn more quickly. It is blown into the combustion chamber of a boiler where it is burnt at high temperature.

2. The hot gases and heat energy produced converts water in tubes lining the boiler into steam.

3. The high-pressure steam is passed into a turbine containing thousands of propeller-like blades. The steam pushes these blades causing the turbine shaft to rotate at high speed. The steam is condensed and returned to the boiling chamber where it is heated again.

4. The shaft rotation engages the wire coils and magnets in a generator connected to it. This charged magnetic field produces electricity

5. Electricity is sent to the switchboard (transformer) where it is regulated and sent via on-land cables to homes.

Using coal to produce energy causes many some problems, usually on a greater scale than the use of oil or gas. These problems include acid rain, sulfur oxide emission, carbon dioxide emission, poorer land, hazardous waste and others.

Several forms of coal exist in the world. Anthracite, bituminous coal, lignite, and sub-bituminous coal are all different types that are used by humans.

What is Petroleum (Crude Oil)?

Crude oil (a non-renewable resource) is usually found in underground areas called reservoirs. It is liquid in nature and yellowish black in color. They are composed mainly of hydrocarbons and organic compounds. They are usually discovered by oil prospecting scientists.

Sometimes, petroleum and crude oil are used to mean the same thing, but petroleum itself is a broad range of petroleum products including crude oil itself.


We use the term 'petroleum products after crude oil is refined in a factory.

Crude oil can exist either deep down in the earth's surface or deep below the ocean beds. Oil drills mounted in the oceans are known as offshore drills

In oil drilling, a structure called 'derrick' is built with pipes going down to the reservoir and bringing the oil to the surface.

Saudi Arabia, USA, Russia, China and Iran are among the top crude oil producers in the world, and the USA is the world's biggest consumer of crude oil, followed by China. (source: USEIA)

The process of generating electricity from crude oil is very similar to that of thermal coal, which we saw on the previous page.

Below is a summary of the process that turns crude oil into electricity:

Oil is burnt in turbines in power stations to produce extreme heat, which is used to create high-pressure steam.

This steam is used to spin a turbine very fast by pushing against metal blades.
.
The blades turn a generator containing wires and magnets and magnetic field produces electricity.

The electricity flows to a transformer, which changes it to very high voltage electricity. The transformer also regulates the amount of electricity that is produced and supplied.

Electricity is sent to homes, factories and other places in the world.

But Crude Oil can be used for other things too:
A great chunk of all the total crude oil in the world is processed as gasoline, which we use for our cars. They can also be processed into liquid products such as rubbing alcohol, or solid products such as nail polish, water pipes, shoes, wax and crayons, roofing, vitamin capsules, and many other items.

Because crude oil is liquid in nature, spills from offshore drills and fuel tankers harm the environment a lot, especially marine life.

 What is Natural Gas? Natural Gas is colorless, shapeless, and odorless in its pure form. Unlike other fossil fuels, natural gas is clean burning and emits lower levels of potentially harmful byproducts into the air. It is therefore called "Clean Gas'.

While natural gas is formed primarily of methane, it can also include ethane, propane, butane and pentane. It is one of the gases that are formed by the same formation of fossil fuels.

The main ingredient in natural gas is methane, a gas (or compound) composed of one carbon atom and four hydrogen atoms.

Natural gas supplies about 23.8 percent of the world's energy. Gas is extracted by drilling wells deep into the ground, through many layers or rock to reach the gas deposits.

Natural gas comes in two main types:
The first and conventional type is found in permeable sandstone reservoirs. The second, unconventional types are found in other places such as in coal deposits (eg. Coal Steam Gas, CSG) or shale rock formations (eg. Shale Gas)

In recent time, shale gas has become very popular in the USA and is mainly drilled by a process called Hydraulic Fracturing (fracking). It is popular because its carbon emission is about half that of coal, and is seen as environmentally friendlier. The USA is known to be the world’s largest producer of shale gas.

“The International Energy Agency currently estimates that global recoverable shale gas resources stand at 7,345 trillion cubic feet, so it's conceivable that this resource could one day offer similar benefits to other countries”.
Source: Chevron

Similar to other energy types, natural gas is burned to produce pressurized gas that spins the blades of turbines. The spinning causes some metal coils and magnets in a generator to produce electrical current, that is connected to a transformer and further supplied to homes.

What is Propane? Propane is an energy-rich gas. Its chemical formula is C3H8.

It is one of the liquefied petroleum gases (LPGs) that are found mixed with natural gas and oil. Propane and other liquefied gases, including ethane and butane, are separated from natural gas at natural gas processing plants, or from crude oil at refineries. The amount of propane produced from natural gas and from oil is roughly equal.

LPG provides a convenient means of powering heating, cooking and other processes, regardless of where your home is located.


How does LPG compare with other fuels?

LPG produces no harmful or dangerous waste
LPG, when burned, produces less CO2 than coal and oil
LPG burns cleanly with no soot and very few SO2 and NOx emissions
LPG poses no ground and water pollution hazards
LPG delivers significant fuel cost savings, and is approximately 50% cheaper than diesel
LPG is a by-product so there is no wastage
LPG boilers are cheaper to install than oil boilers and less expensive to maintain
LPG can be used alongside renewable technologies

What is Uranium (Nuclear Energy)?
Nuclear energy is energy in the nucleus (core) of an atom. Atoms are tiny particles that make up every object in the universe. There is enormous energy in the bonds that hold atoms together.
It is usually in a form of heavy metal, naturally occurring in most rocks, soil, and even in the ocean! It is found in many places in the world. Energy from uranium is called nuclear energy.

Power generated from a nuclear reaction is similar to that of fossil fuels because they all use heat to turn blades (turbines) to generate power.
A nuclear power plant uses uranium as fuel. Uranium pellets are combined into large fuel assemblies and placed in a reactor core.

In that chamber (reactor), uranium atoms can be made to split, or fission, to release heat. 'Fission' is the process of splitting the uranium atom to form smaller atoms. A kilogram of natural uranium produces as much heat as 20 tonnes of coal. This is harnessed to make steam and generate power.
Uranium was first discovered by a German Scientist called Martin Klaproth in 1789. The chamber in which the fission takes place is called a Reactor. In this reactor, uranium fuel is assembled in such a way that a controlled fission chain reaction can be achieved.

It is believed that Uranium was named after the planet Uranus, and it provides the main source of heat inside the earth. Uranium (say: yoo-ray-nee-um) is NOT a fossil fuel. As of 2013, there are over 430 nuclear power reactors in 30 countries and many more are being built.
CO2 emissions from nuclear fuel is very low, even lower than hydro-power. Nuclear power plants are very expensive to build. It also produces very dangerous waste in the form of radioactive waste, even though the amount of waste is small (about 3% of the plants waste). These are usually disposed of very deep underground where geological conditions are stable and far from human or environmental exposure.
In 2011, a tsunami struck Japan and caused problems with its nuclear power plant in Fukushima. After that tsunami, there have been a couple of leakages of highly radioactive water from the plant's storage tanks into its environment. Radioactive materials are very dangerous to humans and the environment.
There are laws that check that countries with nuclear plants comply with safety rules and also do not misuse their plants for developing nuclear weapons. 


                                                                     X  .  IIIII
                                                             What Kinds Energy  ?

What is energy?

Look around you. Is anything moving?
Can you hear, see or feel anything? Sure... this is because something is making something happen, and most probably, there is some power at work. This power or ability to make things happen is what we can call energy. It makes things happen. It makes change possible.                        

Look at the sketch below to see an example of things working, moving, or happening... with energy.



Energy moves cars along the roads and makes aeroplanes fly. It plays our music on the radio, heats our rooms and lights our homes. Energy is needed for our bodies, together with plants to grow and move about.

Scientists define ENERGY as the ability to do work.
Energy can be neither created nor destroyed.


KINDS OF ENERGY
With the above explanation in mind, let us learn more.

Energy can be (is) stored or transferred from place to place, or object to object in different ways. There are various kinds of energy.

Kinetic Energy

All moving things have kinetic energy. It is energy possessed by an object due to its motion or movement. These include very large things, like planets, and very small ones, like atoms. The heavier a thing is, and the faster it moves, the more kinetic energy it has.

Now let's see this illustration below.
There is a small and large ball resting on a table.


Let us say both balls will fall into the bucket of water.
What is going to happen?

You will notice that the smaller ball makes a little splash as it falls into the bucket. The heavier ball makes a very big splash. Why?

Note the following:
1. Both balls had potential energy as they rested on the table.
2. By resting up on a high table, they also had gravitational energy.
3. By moving and falling off the table (movement), potential and gravitational energy changed to Kinetic Energy. Can you guess which of the balls had more kinetic energy? (The big and heavier ball)

Let's see another classic example.
If you are in a hot room and you turn on the fan, what do you begin to feel? Air (wind). The speedy movement of the fan's blades has kinetic energy, which is then transferred into air (wind) that you now feel. Other examples of Kinetic Energy include a moving car, moving wheel, and a moving arrow. 


Mechanical Energy
Mechanical energy is often confused with Kinetic and Potential Energy. We will try to make it very easy to understand and know the difference. Before that, we need to understand the word ‘Work’.

‘Work’ is done when a force acts on an object to cause it to move, change shape, displace, or do something physical. For, example, if I push a door open for my pet dog to walk in, work is done on the door (by causing it to open). But what kind of force caused the door to open? Here is where Mechanical Energy comes in.
Mechanical energy is the sum of kinetic and potential energy in an object that is used to do work. In other words, it is energy in an object due to its motion or position, or both. In the 'open door' example above, I possess potential chemical energy (energy stored in me), and by lifting my hands to push the door, my action also had kinetic energy (energy in the motion of my hands). By pushing the door, my potential and kinetic energy was transferred into mechanical energy, which caused work to be done (door opened). Here, the door gained mechanical energy, which caused the door to be displaced temporarily. Note that for work to be done, an object has to supply a force for another object to be displaced.
Here is another example of a boy with an iron hammer and nail. In the illustration below…

(1) The iron hammer on its own has no kinetic energy, but it has some potential energy (because of its weight).

(2) To drive a nail into the piece of wood (which is work), he has to lift the iron hammer up, (this increases its potential energy because if its high position).

(3) And force it to move at great speed downwards (now has kinetic energy) to hit the nail.
The sum of the potential and kinetic energy that the hammer acquired to drive in the nail is called the Mechanical energy, which resulted in the work done.

Sound energy

Sound is the movement of energy through substances in longitudinal (compression/rarefaction) waves.

Sound is produced when a force causes an object or substance to vibrate — the energy is transferred through the substance in a wave. Typically, the energy in sound is far less than other forms of energy.

Let's see this illustration.


A vibrating drum in a disco transfers energy to the room as sound. Kinetic energy from the moving air molecules transfers the sound energy to the dancers eardrums. Notice that Kinetic (movement) energy in the sticks is being transferred into sound energy.

Sound vibrations create sound waves which move through mediums such as
air and water before reaching our ears.

The diagram below shows how a sound wave is represented:

Sound energy is usually measured by its pressure and intensity, in special units called pascals and decibels. Sometimes, loud noise can cause pain to people. This is called the threshold of pain. This threshold is different from person to person. For example, teens can handle a lot higher sound pressure than elderly people, or people who work in factories tend to have a higher threshold pressure because they get used to loud noise in the factories. 

Heat (Thermal energy)
Matter is made up of particles or molecules. These molecules move (or vibrate) constantly. A rise in the temperature of matter makes the particles vibrate faster. Thermal energy is what we call energy that comes from the temperature of matter. The hotter the substance, the more its molecules vibrate, and therefore the higher its thermal energy.

For example, a cup of hot tea has thermal energy in the form of kinetic energy from its vibrating particles. When you pour some milk into your hot tea, some of this energy is transferred from the hot tea to the particles in the cold milk. What happens next? The cup of tea is cooler because it lost thermal energy to the milk. The amount of thermal energy in an object is measured in Joules (J)
We cannot discuss thermal energy without touching on Temperature. Heat and Temperature do not mean the same thing.
Temperature
The temperature of an object is to do with how hot or cold it is, measured in degrees Celsius (°C). Temperature can also be measured in a Fahrenheit scale, named after the German physicist called Daniel Gabriel Fahrenheit (1686 – 1736). It is denoted by the symbol 'F'. In Fahrenheit scale, water freezes at 32 °F, and boils at 212 °F. In Celsius scale, water freezes at 0°C and boil at 100°C.
A thermometer is an instrument used to measure the temperature of an object.
Let's look at this example to see how thermal energy and temperature are related:
A swimming pool at 40°C is at a lower temperature than a cup of tea at 90°C. However, the swimming pool contains a lot more water. Therefore, the pool has more thermal energy than the cup of tea even though the tea is hotter than the water in the pool.
Let us see this example below:


If we want to boil the water in these two beakers, we must increase their temperatures to 100°C. You will notice that will take longer to boil the water in the large beaker than the water in the small beaker. This is because the large beaker contains more water and needs more heat energy to reach 100°C.

Conduction, Convection and Radiation.

Heat can be transferred from particle to particle or object to object in three different ways. These are Conduction, Convection and Radiation.

Chemical energy

Chemical Energy is energy stored in the bonds of chemical compounds (atoms and molecules). It is released in a chemical reaction, often producing heat as a by-product (exothermic reaction). Batteries, biomass, petroleum, natural gas, and coal are examples of stored chemical energy. Usually, once chemical energy is released from a substance, that substance is transformed into an entirely new substance.

For example, when an explosive goes off, chemical energy stored in it is transferred to the surroundings as thermal energy, sound energy and kinetic energy.

Let's see one good example in the fire-place illustration below.

The dry wood is a store of chemical energy. As it burns in the fireplace, chemical energy is released and converted to thermal energy (heat) and light energy. Notice that the wood now turns into ashes (a new substance)

Food is also a good example of stored chemical energy. This energy is released during digestion. Molecules in our food are broken down into smaller pieces. As the bonds between these atoms loosen or break, a chemical reaction will occur, and new compounds are created. When the bonds break or loosen, oxidation occurs almost instantly.


In the example above, notice that new compounds are formed from the breakdown of other molecules or atoms. Chemical reaction causes that.

A chemical reaction is involved in this breakdown. The energy produced keeps us warm, maintain and repair bodies, and makes us able to move about. Different foods store different amounts of energy.
Energy in food is measured in kilocalories (or Calories). Can you think of some very good examples of chemical energy?

Click to see an example of how chemical energy is released from coal to produce electricity.

   

Electrical energy

Matter is made up of atoms. In these atoms, there are some even small stuff called electrons that are constantly moving. The movement of these electrons depends on how much energy it has. This means every object has potential energy, even though some have more than others.

Humans can force these moving electrons along a path from one place to the other. There are special mediums (materials) called conductors, that carry this energy. Some materials cannot carry energy in this form, and they are called insulators. We generate electrical energy whey we succeed in causing these electrons to move from one atom to the other, with the use of magnetic forces.



Once we harness electrical energy, it can be used for work or stored.

How does an electric current work?
A battery transfers stored chemical energy as charged particles called electrons, typically moving through a wire. For example, electrical energy is transferred to the surroundings by the lamp as light energy and thermal (heat) energy.

Lightning is one good example of electrical energy in nature, so powerful that it is not confined to a wire. Thunderclouds build up large amounts of electrical energy. This is called static electricity. They are released during lightning when the clouds strike against each other.


Gravitational Energy, Potential Energy

It is important to know the difference between potential energy and gravitational energy.

Every object may have Potential energy but Gravitational energy is only stored in the height of the object. Any time that a heavy object is kept high up, a force or power is likely to be holding it up there. This is the reason why it stays up and does not fall. It is important to note that the heavier the object, the more its potential energy.
Let's see the diagram below:

Consider Mr Green throwing a bag of gold coins to Mr Red, who is up a tower. As Mr Green throws the bag from A to B, potential energy is transferred from Mr Green into the bag, which now has kinetic energy.

As the bag moves upwards, kinetic energy decreases, and gravitational energy increases. At the highest point (B) Kinetic energy is zero, and Gravitational potential energy is highest.

As the bag did not get to Mr Red, it starts falling from point B downwards due to gravity. It starts falling slowly (kinetic energy is low) and then speeds up downwards.

At point A, the bag is at full speed and kinetic energy is highest, whiles gravitational energy is nearly lost.

When the bag of gold coins hits the ground, kinetic energy is converted into heat and sound by the impact.



It is worth noting that the higher the gravitational energy of an object moving downwards, the lower the kinetic energy, and the lower the kinetic energy of an object moving upwards, the higher its gravitational energy.

 Radiant Energy
Radiant energy is the energy of electromagnetic waves. It is a form of energy that can travel through space. For example, we receive the heat from the sun, which is located very far from the earth via radiation. The sun's heat is not transmitted through any solid medium, but through a vacuum. This is possible by electromagnetic waves.
Before we go any further, let us understand what electromagnetic waves are.
Each time static energy from electric and magnetic force come together, they induce an electric field around them.

An example of electric static force is the shock you get when you hold a metal door knob.

An example of a magnetic force is the pull that attracts metals to the magnet. Now, the electrical field induced causes waves, called electromagnetic waves, and they can travel through a vacuum (air), particles or solids. These waves resemble the ripple (mechanical) waves you see when you drop a rock into a swimming pool, but with electromagnetic waves, you do not see them, but you often can see the effect of it.
The energy in the electromagnetic waves is what we call radiant energy.
There are different kinds of electromagnetic waves and all of them have different wavelengths, properties, frequencies and power, and all interact with matter differently. The entire wave system from the lowest frequency to the highest frequency is known as the electromagnetic spectrum. The shorter the wavelength, the higher its frequency and vice versa. White light, for example, is a form of radiant energy, and its frequency forms a tiny bit of the entire electromagnetic spectrum.

In the illustration above, you will see the different radiant energy levels represented by their wavelengths.
When radiant energy comes into contact with matter, it changes the properties of that matter. For example, when micro-waves (which forms part of the entire spectrum) are set off in a microwave oven, the water molecules in the food are charged and caused to vibrate billions of times per second, generating heat, that causes the food to cook. The microwave oven works with the concept of radiant energy (electromagnetic waves).

Energy Stored

Energy cannot be created or destroyed, but it can be saved in various forms. One way to store it is in the form of chemical energy in a battery. When connected in a circuit, energy stored in the battery is released to produce electricity.


If you look at a battery, it will have two ends: a positive terminal and a negative terminal. If you connect the two terminals with wire, a circuit is formed. Electrons will flow through the wire and a current of electricity is produced.
Energy can also be stored in many other ways. Batteries, gasoline, natural gas, food, water towers, a wound up alarm clock, a Thermos flask with hot water and even pooh are all stores of energy. They can be transferred into other kinds of energy.


Energy Transfer

In this diagram, we shall look at a bigger picture of how energy is transferred from one object to another, and from one state to the other. Take a close look and read the notes below:

A: Sun, source of solar energy. It transfers thermal (heat) and light energy to plants, humans and animals.

B: River, streams and waterfalls moving downstream are all a source or water energy (HydroPower). They are a store of kinetic energy by their movement downstream. Waterfalls also have gravitational energy.
C: Thermal and light energy from the sun is stored in plants as chemical and potential energy. When humans eat (plants) the stored energy is transferred to us. We use this energy to do work.

D: Heat energy from the sun is transferred to water bodies. This warms the water up. The result is stored thermal energy. The warm water heats the air over it. Warm air rises, so the air is now set into motion. The moving air now has kinetic energy.


E: Kinetic energy in the moving air is a source of energy called Wind Energy. Wind can turn the blades and generate electrical energy, which we use in our homes.

F: Energy from the sun is captured as Solar energy by cells and panels on top of our roofs. Solar energy is then transferred into electrical energy, which we use to warm our homes and turn the TV and computers on.


Energy Dissipation


Using the snooker cue means you are transferring kinetic energy from the cue to the ball, which already has potential energy. As the ball moves, notice that its kinetic energy released decreases, as it comes to a stop.

When you slide a snooker ball on the board (table) it moves quickly, and then slowly, and gradually comes to a stop. This means that the kinetic energy (moving) of the ball decreases and eventually to zero when the balls come to rest.
With zero external force on the pool table, the energy of the ball must be conserved. Then, what happened to the kinetic energy? Kinetic energy has been dissipated through friction.


                                                              X  .  IIIIII 
                                                     WHAT IS A MACHINE ? 

What is a machine?

A machine is any device that does work. Machines make our lives easier because they reduce the amount of energy, power, and time we need to get one thing done by magnifying our input force.

A machine can increase the magnitude or the distance of a force but not both at the same time.

Machines come in many sizes, shapes and forms. Some machines are very simple in its makeup and use whilst others are very complex. For example, a spade is a machine (a simple machine), and a space shuttle is a machine too (a complex machine).

For this lesson, we shall be looking at simple machines.

Consider the illustration below:
To bring the load (wagon with a mound of dirt in it) to the lower surface, a person has to carry that carefully. That is a lot of muscle work. To make that easier, we can just put a ramp there, and just give the wagon a little push — right? Yes, and then the load will just slide down on its own.

In the example above, we have used a very simple trick of a simple machine to bring down that load of dirt — easily!

Here is another scenario: A bulldozer at work! Take note of the simple machine units (levers, wheel and axle, wedge) that are combined to build a complex machine.

To push a mound of dirt on a piece of land, it can take a person with a shovel a lot of time and energy to do so. However one person with a complex machine can do that work in no time. Here, the complex machine, which is a complex combination of simple machine units, uses mechanical energy and electrical energy to do that job. It is not the same as a simple machine. This bulldozer is an example of a compound or complex machine.



Types of machines

Machines come as two major kinds — Simple Machines and Complex Machines.

Simple Machines
A simple machine is a tool, device or object with few moving parts that help us do work. Simple machines have been in use for a very long time. Early humans used simple machines to push, pull, lift, divide and crush things. They used simple machines to row rafts over water, build houses, split firewood, and carry heavy things from place to place. Today, there are simple machines in every place and all around us.

There are six types of simple machines — the inclined plane, the wedge, the screw, the lever, the wheel and axle, and the pulley. These six have very specific features and do unique jobs, even though some may work in similar ways. In fact, some simple machines may be a combination of simple machines.

Important:
Simple machines, unlike complex ones, do not work on their own. They only increase the pull or push, (force or effort) that a person uses, increase or decrease the distance, or change the direction of a movement so that more work can be done. They can:
transfer a force from one place to another
change the direction of a force
increase the magnitude of a force
increase the distance or speed of a force

Features of a simple machine
They do not use electricity
They have one or fewer moving parts
They give us mechanical advantage
Even though they make work easier for us, they still need input (force or effort) from a person.
They make tough jobs easier by changing the force, direction or speed of a movement

Complex Machines
Simple machines are different from complex (or compound machines). Complex machines, like trucks or wagons, or bicycles use many moving parts. They combine many simple machines such as levers, pulleys, and gears to get work done. 

The Inclined Plane

An inclined plane is a simple machine with no moving parts. It is simply an even sloping surface. It makes it easier for us to move objects to higher or lower surfaces, than if we lifted the objects directly upwards. It is believed that ancient Egyptians used inclined planes to carry heavy stones to build pyramids.

‘Inclined’ means a raised end or raised at one end. An inclined plane may be a constructed frame, or just a piece of log leaning against a higher point. An inclined plane is also called a ramp.

In the illustration below, the man uses a piece of metal as a ramp to move the hand-truck into the van.

An inclined plane has a horizontal side (A), (the distance from the the lower end of the slope to the base of the vertical). It also has a vertical side (B), (from the base up to the top of the sloped surface). The sloped surface is where the man is pushing his hand truck.

Tradeoff
There is a tradeoff with this simple machine. If the slope is gentle, a person has to push or pull the object over a longer distance, but with very little effort. If the slope is steep, a person has to push or pull the object over a very short distance, but with more effort.

Trade off helps us to understand the mechanical advantage of inclined planes. For example; there is a greater mechanical advantage if the slope is gentle because less force will be needed to move an object up or down the slope.

Some good examples of inclined planes are accessibility ramps and roofs of houses.


The Wedge (ramp)

A wedge is simply a triangular tool, often made of metal, wood, stone or plastic. It is thick on one end and tapers to a thin or sharp edge on the other end. Technically it is an inclined plane (or two inclined planes put together to form a triangle) that moves. A wedge may be attached to a handle to make it easier to use. Good examples of wedges are nails, knives, axes and your teeth!

A wedge can be used in many ways:
To cut (knife)
To split (axe)
To tighten and to hold back (doorstopper)
To hold together (nail)
To scrape (blades on the snowplough or farm grader)

Wedges work by changing direction and force applied to it. Here is an illustration:Diagram of change in direction and force.

From the above, you will notice that the force applied to the thick end of the wedge overcomes the resistance of the wood. The force is directed downwards, but the wedge directs the force sideways as it drives into the wood.

A wedge may be a single wedge or double wedge. Each does a slightly different job. An axe is a double wedge (see diagram above) and a chisel is a single wedge.

Trade-off
The longer and thinner a wedge is (sharper), the more work it does with little effort. If the wedge is shorter and has a wider angle at the tip, one needs more force to do the work.

The mechanical advantage of a wedge is higher when the wedge is longer with a thinner tip.

Wedges have been in use for millions of years. Earlier humans used wedges made of hard rocks and stones to hunt (like spears), cut and trim trees and carve stones. The concept of wedges is also used in jets and modern cars. You will notice that jets, fast cars, speed boats and trains have pointed noses. This helps them cut through the air (air acts as a resistance). This feature of pointed noses cutting through air is known as aerodynamics.

The Screw

A screw is simply an inclined plane around a cylinder. To describe this better you can view it as a cylinder with a head (solid top) at one end and a pointed tip (like a nail) at the other end. More importantly, it has ridges winding around it. The correct term for the ridges (or grooves) around the shaft or cylinder is the thread.

The distance between threads are the same for each screw but are different on other screws. The distance between the threads is called Pitch.

Screws are very useful for holding things together. They can pull or push an object together. They can be used to lift very heavy objects and tighten things too.

Nail and Screw
These two are not the same. Unlike the nail, a screw has ridges around the shaft. It is harder to drive a screw into a piece of wood because the ridges on the screw create a lot of friction and resistance. To drive a screw into the wood, it has to turn in a circular motion by a screw-driver.

Other kinds of screws

Bolt: A bolt is a kind of screw, but does not have a pointed tip. It is not drilled into place, but rather, a hole is made for the bolt to go through. Then a nut is placed at the end to screw the bolt through. Bolts are very powerful in holding things together.

Drill Bit: This is a type of screw that can make holes in wood, plastic, metal and stones when attached to an electric drill. Like the regular drill, it is pointed at one end, and it has threads too. The drill bit has deeper grooves that carry pieces of the wood from the hole to the surface as the drill bit turns.

Examples of screws
Some good examples of screws are bolts, screws, bottle tops, guitar tuners, light bulbs, faucet taps and cork openers. Can you think of a screw device in your home?

Mechanical Advantage
Mechanical advantage depends on the space between the threads and the length (and thickness) of the screw. The closer the threads are, the greater the mechanical advantage. It is easier to drive a screw into an object if the thread spacing is smaller. This takes less effort but more turns. If the spaces between the threads are wider, it is harder to drill a screw into an object. It takes more effort but fewer turns.

The Lever

A lever is simply a plank or ridged beam that is free to rotate on a pivot. It is perfect for lifting or moving heavy things. It is a very useful simple machine, and you can find them everywhere. Good examples of levers include the seesaw, crowbar, fishing-line, oars, wheelbarrows and the garden shovel.

Parts of a lever
Levers have four very important parts — the bar or beam, the fulcrum (the pivot or the turning point), effort (or force) and the load.

The beam is simply a long plank. It may be wood, metal or any durable material. The beam rests on a fulcrum (a point on the bar creating a pivot).

When you push down one end of a lever, you apply a force (input) to it. The lever pivots on the fulcrum, and produces an output (lift a load) by exerting an output force on the load. A lever makes work easier by both increasing your input force and changing the direction of your input force.

The Three Lever Classes
The parts of the lever are not always in the same arrangement. The load, fulcrum, and effort may be at different places on the plank.

Class One Lever
In this class, the Fulcrum is between the Effort and the Load. The mechanical advantage is more if the Load is closer to the fulcrum. Examples of Class One Levers include seesaws, boat oars and crowbar.

Class Two Lever
In this class, the Load is between the Effort and the Fulcrum. The mechanical advantage is more if the load is closer to the fulcrum. Examples of Class Two Levers include wheelbarrows

Class Three Lever
In this class, the Effort is between the Load and the Fulcrum. The mechanical advantage is more if the effort is closer to the load. An example of Class Three Lever is a garden shovel.
   












The Wheel and Axle

This simple machine involves two circular objects — a larger disc and a smaller cylinder, both joined at the centre. The larger disc is called the wheel, and the smaller cylindrical object or rod is referred to as the axle. Sometimes, there may be two wheels attached to both ends of the axle. A wheel alone or an axle alone is not a simple machine. They need to be joined to be called a simple machine.

If you look closely at how a wheel and axle works, you will notice that it is a kind of class one lever. Here, an action on the axle (turning the axle) will cause an output at the other end (wheel turns too). The fulcrum is where the axle meets the wheel.

The Wheel and axle work in two basic ways.

Force applied to wheel:
Let us take a screwdriver for instance. If you apply a force to the wheel (the handle), the wheel spins and multiplies the effort to make the output force of the axle (shaft) greater.

A simple door knob is another great example of the wheel and axle. The locking mechanism of the door knob is inside of the door and can only be controlled by the knob. Since it will be difficult turning the axle to open the door, we can turn the wheel instead and that does that job for us.

Force applied to axle:
Now let us also consider a windmill. If you apply a force to the axle, it will multiply the force to the wheel (blades) and result in a greater distance covered. It is because the wheel is larger than the axle and covers more area. A ceiling fan works in a similar way. As the axle turns, it powers the larger wheel (fan blades) to cause the desired output.

The Wheel and axle are perfect for turning turbines and fans; They are also used in automobiles. For example, when you turn the steering wheel of a car, your effort is multiplied by the axle and results in more turns of the car wheels.

Gears
A gear is simply a special wheel with teeth called threads on the outside.  



The Pulley

Have you seen your school flag being raised before? This is possible with a simple pulley. When you pull down on the rope, the pulley turns and the flag goes up. Pulleys change the direction of the force.

A pulley is simply a wheel with a groove in it, and a rope in the groove. It is also called a drum or a sheave. The groove is important because it helps to keep the rope in place. It is used to lift up or lower heavy objects. With a pulley, an object to be lifted can be tied to one end of the rope, and a force is applied to the other end by pulling the rope downwards. The downward force turns the wheel with the rope and pulls the load upwards at the other end.

Types of Pulleys
There are three types of pulleys. Each pulley system depends on how the wheel and rope are put together.

Fixed Pulley
This is the simplest form of pulleys. Simple pulleys have their axles fixed in place and cannot be moved. The rope moved in the groove of the pulley but the wheel is fixed to one spot. The wheel on your school flag pole is a good example.

Movable Pulley
In a movable pulley, (see diagram on the left) the load is attached to the pulley and both of them can move from place to place. In this type, one end of the rope is attached to a fixed point that does not move. With a movable pulley, you need less effort to lift a load. Can you tell how the movable pulley is similar to the Class Two Lever? Both of them have the load between the effort and the fulcrum!

Compound Pulley
This is also called a combined pulley. It is a combination of pulleys designed to make the effort less than half of the weight of the load. This kind is very common at construction sites where cranes lift very heavy steel and concrete objects. One good example of a compound pulley is a Block and Tackle.
 
 Important terms

Lever
A solid bar that rotates around a pivot and makes it easier to lift a load, move a heavy object or apply a force.

Force
A push or a pull. The unit of Force is called the Newton. Force (F) = Mass x Acceleration.

Work
The movement of an object resulting from a force applied to it. Movement is usually in the direction of the force. To calculate Work done, multiply Force (F) by Distance (D).  W=FxD

Input Force
The effort or force you put into a machine.

Output Force
The force the machine produces as a result of the input force.

Power
Power is the rate at which Work is done. Power is measured in Watt. Power = Work / Time

Mechanical Advantage (MA)
Simple machines do not work on their own. Someone has to apply input force to make it do work. MA is the ratio between the input force and the output force. A Mechanical Advantage is produced when a simple machine amplifies a small input force to produce a greater output force.

Rotation Point
The axis or center that a wheel or disc spins.

Work
The movement of an object resulting from a force applied to it. Movement is usually in the direction of the force.

                                                                      X  .  IIIIIII  

                                        Elements, Compounds, Substances and Mixtures  


Elements, Compounds, Substances and Mixtures

In the study of science, it is very important to know that all solids are not the same, all liquids are not the same, and all gases are never the same. In addition to that, it is important to understand why all liquids are not the same, and why some are purer than others, in terms of their chemical makeup or compositions. This is why the classification of matter is important.

Classification of matter
Matter can be classified into two categories: pure substances and mixtures. This classification is based on the internal composition of that matter. Using composition to describe matter is better than using its state, because the internal makeup makes matter unique, and not its phase or state. Example, water () can be vapor, solid or the usual liquid. This means that scientifically, it is not correct to say water is a liquid, even though we all know that water is usually a liquid.


In a similar vein, classifying matter only according to its color, size, or weight is not enough because two identical objects can be of the same color, but their internal makeup may be different. Example, a glass of water from a lake may look and weigh the same as another identical glass of water from another lake — but it does not mean they are the same. They are all water, but the chemical compositions may be very different.

So, in this lesson, we shall see more about the classifications and the various ways and forms in which matter is made up, mixed up and if they can be separated at all.

First, it is very important to be very clear what some words mean. Let us begin with ‘Elements’ 


Elements

An element is a substance made from only one type of atom. For example, Oxygen () is an element made up of ONLY oxygen atoms. To understand this better, let us see the how atoms behave.



Every element is made up of atoms. Atoms are the smallest piece that can exist in an element. You will need to put millions of atoms together to get an element of about half millimeter in size. An atom is made up of ‘Electrons, Protons and Neutrons’.

The diagram on your left is an illustration of an atom. The center part is the nucleus.



Atoms in some elements do not join up with other atoms of the same element. An example is Helium. Helium atoms exist alone and can look like this:


Some atoms can also join up with other atoms of the same element. When two or more atoms join up, they form a molecule. Oxygen, () is a molecule because it has two atoms joined together. An oxygen molecule looks like those in the diagram above.

Elements are pure in nature. They may vary in size as long as the atoms joining to make its molecules are the same. As soon as a different atom joins (bonds), it ceases to be an element — it is now a compound.

Sometimes, atoms can join up with other atoms of other elements in chemical bonds. When that happens, a compound is formed. This means that a molecule can be made up of two atoms of the same element, OR can be made up more atoms of different elements. 

  

Substances

A substance is simply matter with definite chemical composition and distinct properties. It is matter that is characterized by a constant composition in terms of its molecules, formulae and atoms, as well as physical properties such as density, refractive index, electric conductivity, melting point, and so on.

A substance can be an element or a compound but NOT a mixture. It can also be matter that exists in its pure form, usually called a pure substance. A few examples of substances include Water (), Hydrogen () and Neon (Ne).

Other examples of chemical substances commonly seen in pure form are salt (sodium chloride), diamond (carbon) and gold.



The diagram above shows the classification of matter and where substances fit.

Substances cannot be separated into components by physical separation techniques. Some substances, like water, can be broken down into elements by a chemical reaction (to break chemical bonds). A substance can be solid, liquid, gas, or plasma. 

What is a Mixture

A mixture is formed of little bits of one or more substances mixed together. Usually, the parts can be separated from each other by physical means, because it does not involve any chemical reactions or bonds.

Types of Mixtures
A mixture can involve two or more substances of the same phase or different phases. For example you can mix water and sand (liquid and solid), sugar and salt (solid and solid), water and oil (liquid and liquid) or nitrogen and oxygen (gas and gas). Clearly, mixtures can vary a lot and can be homogeneous or heterogeneous. Homogeneous mixture:
Mixtures involve mixing substances, so let us first be clear what a homogenous substance is. When a sample of matter has the same composition throughout, we call that substance a homogeneous substance. A cup of water will have the same chemical composition throughout (). That makes it a homogeneous substance. A piece of gold will also have the same chemical composition, making it a homogenous substance. Homogeneous Mixtures behave in a similar way — the substance formed appear to have the same chemical composition. Alloys and Solutions are Homogeneous mixtures.
Click on each to find out more:



Heterogeneous Mixture
A mixture can also result in two or more phases clearly separated by boundaries. Very often, the separation can be clearly seen by the eye. A heterogeneous mixture is one that does not have uniform properties and composition. Take a look at a bowl of cereal with nuts. A spoon full will surely have a different number of nuts than a second spoonful taken at random. Another example—take some sea-sand into your palms. Look at it closely and you will notice that some sand particles are bigger than others, and the colors of some particles may be different too. They are NOT uniform in any way!
Heterogeneous mixtures include colloids, emulsions or suspensions.
Click on each to find out more:

  

Separating Mixtures

Mixtures come in many forms and phases. Most of them can be separated, and the kind of separation method depends on the kind of mixture it is. Below are some common separation methods:

Paper Chromatography
This method is often used in the food industry. It is used to identify chemicals (coloring agents) in foods or inks. For example, if a scientist wants to know how many substances are in a particular blob of ink, paper chromatography can be used.

Filtration
This is a more common method of separating an insoluble solid from a liquid. An example of such a mixture is sand and water. Filtration is used in water treatment plants, where water from rivers is filtered to remove solid particles.

Evaporation
Evaporation is great for separating a mixture (solution) of a soluble solid and a solvent. The process involves heating the solution until the solvent evaporates (turns into gas) leaving behind the solid residue.

Simple distillation
This method is best for separating a liquid from a solution. In a way, the concept is similar to evaporation, but in this case, the vapor is collected by condensation. For example, if you want to separate water from a salt solution, simple distillation would be great for this. 

Fractional distillation
Similar to simple distillation, fractional distillation is best for separating a solution of two miscible liquids. (Miscible liquids are liquids that dissolve in each other). The Fractional method takes advantage of the different boiling points of the two liquids. 

Magnetism
Magnetism is ideal for separating mixtures of two solids with one part having magnetic properties. Some metals like iron, nickel and cobalt have magnetic properties whiles gold, silver and aluminum do not. Magnetic elements are attracted to a magnet. Separating funnel
In this technique, two liquids that do not dissolve very well in each other (immiscible liquids) can be separated by taking advantage of their unequal density. A mixture of oil and water, for example, can be separated by this technique.  

Chemical Formulae

Very often in the study of science, you shall come across many elements and compounds that are represented by letters and numbers. These symbols are written in a definite way to tell us what the elements and compounds are made up of. They also tell us the various amounts of atoms in any substance.

Every element has a symbol. For example — Fe stands for Iron, O stands for Oxygen and C stands for carbon. It is very important to know the correct symbols of all the elements, because if they are not written properly, they change the entire meaning of it.

For example CO means one element of carbon and one element of oxygen together. This is Carbon Monoxide. It is NOT the same as Co, which is the symbol for cobalt.

The small numbers below the symbols tell us how many atoms of that element are in the molecule. 'O' means one atom of oxygen. means 2 atoms of hydrogen. , means two atoms of Hydrogen and one atom of oxygen. This is a water molecule.

When molecules react with other molecules, they form more complex  compounds, with complex chemical formulae.

Here is an example:
The symbol for Sulphur is S, the symbol sodium is Na and that for Oxygen is O. If the atoms of these three elements react, they form a compound such as (Sodium sulphate) This compound has 2 atoms of Na, 1 atom of S and 4 atoms of O. Compounds with this formulae will be exactly the same anywhere on earth because of its unique composition. The same can be said of (water molecule). If we use the chemical formulae , it will be the same anywhere on earth, BUT if we say water, it will not be the same anywhere on earth because water is generic and may contain other atoms of other elements in it. 

 
Important words

Here are all the words we used in the lesson on matter.  Be sure you have a clear idea of what each word means and how each relate or differ from the other.

Alloys, Atoms, Boiling Point, Chemical change, Chromatography, Colloids, Condensation, Chemical Formulae.

Distillation.

Evaporate, Element, Emulsion, Expansion.

Filtration, Freezing Point.

Gas.

Homogenous mixture, Heterogenous mixture.

Irreversible change.

Liquid.

Matter, Magnetism, Melting Point, Miscible and immiscible substances, Mixture, Molecules.

Physical change,

Separating funnel, Solids, Solution, Solvent, Solute, Suspension, Substance.

Residue, Reversible change, Vapor. 

                                                                     X  .  IIIIIIII   

                                                                     GENETICS 

Introduction to genetics.

Genetics is probably one of the most exciting lessons in biology.
At the same time, it can be a bit confusing because sometimes it is difficult to imagine what the bare eyes cannot see. We will try to make things very simple and easy for you.

What is genetics?

Genetics is the science of studying how living things pass on characteristics (or traits) and its variations in their cell make-up from one generation to the other.

Simply, it is the study of how living things inherit features like eye-colour, nose shape, height and even behavior from their parents.
A scientist who studies genetics is called a geneticist.

Here is a scenario —
If a mother with big blue eyes has a baby boy, soon his eyes begin to look so much like his mummy’s.

He will probably exhibit similar features of his mum’s eyes.

When this happens, the boy probably has inherited some specific genes from his mummy, and the cells in their eyes share some DNA (we will explain this soon).

This inheritance can come about in both sexual and asexual reproduction.

Genetics is not only important in humans. It also applies to plants and other living cells. A plant may pass on traits like number of fruits it bears, color of its’ flowers or its’ root structure via a seed, that will grow into a very identical plant.

In this lesson, we shall learn a bit more about how that is possible and some very important words that we need in our study of genetics. Let us begin with Genes, Chromosomes and DNA. 


Genes

Take a look at yourself. Is there anyone the same as you? No.
You are a person with unique physical, mental, emotional make-up. There has never been anyone as you, and never will be. At the same time, you may look a lot like your big brother, or even like your mum. Probably, you have similar hair colour or eyes, or smile in a very similar way. This complete difference or similarity between your brother or mum and you is determined by something in our body called genes.

So what is a gene?
Genes are instruction manuals in our body. They are molecules in our body that explain the information hidden in our DNA, and supervises our bodies to grow in line with that information.

It is believed that each cell in our body contains over 25,000 genes, all working together. These genes carry specific biological codes or information that determine what we inherit from our parents.

Genes are also a small section of Deoxyribonucleic Acid (DNA), a chemical that has a genetic code for making proteins for living cells. Proteins are the building blocks for living things. Almost everything in our body, bones, blood and muscles are all made up of proteins, and it is the job of the genes to supervise protein production.

Genes are not things we see with our bare eyes. They can only be seen with powerful microscopes, and they are thread-like in nature, found in our chromosomes.

The diagram below shows how a gene is represented.

Altered or mutated genes:
Sometimes our genes do not work well. Sometimes we inherit genes that have some problems. Such genes (also called mutated or altered genes) do not perform their functions well, and cause defects in our organs. Some inherited diseases like cancer and sickle cell have been linked to such mutated or bad genes. There is still a lot of research going on in the study of genes to learn more about them.

Remember we mentioned DNA and Chromosomes along the line? Let us see more about them too.

What DNA and what does DNA stand for?

DNA simply means Deoxyribonucleic Acid. It is a hereditary molecule that is found in almost all living things (cells). DNA carries a code (information) that genes use to make living things grow. It is found in all cells in structures called chromosomes.

DNA is located in the nucleus of cells. This is called ‘nuclear DNA. Some DNA is also located in the mitochondria of the cell and that is also called mitochondrial DNA. All the cells in that living thing carry the same DNA.

There are 4 chemical bases that make up the code in DNA.

These chemical bases are
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)

These chemical bases are contained in the shape of a twisted ladder called The Double Helix.

In humans, all the bases are the same — BUT, the combination or order, or sequence is unique to every individual.

Think of it this way:
All telephone numbers use the same numbers, but each person has a unique combination or sequence. This is how the chemical bases in DNA work.

DNA can duplicate or copy itself. This is why all cells in an individual have the same DNA.

So, the larger picture looks like this:
The strand in the DNA is made up of Letters G A T C. These letters combine in a set way to make words. The words combine to make sentences. The sentences can be called “Gene’ It is the gene that instructs all the cells in the body to perform their functions, as specified in our DNA, including making protein.

What is a chromosomes?

A chromosome is just a compact store of DNA. A chromosome is simply a lot of DNA strands folded and compacted together. This compacting is done in a special way. The Chemical bases in the DNA are held in place by The Double Helix. The Double Helix continues to wrap itself around proteins. They continue to wrap around several protein molecules and into an even bigger compact set which we call Chromosome.

Chromosomes are all contained in the nucleus of the cell.
The number of Chromosomes in a cell depends on what cell it is. Chromosomes in a tiny goldfish may be a lot less than that of a human. In fact, humans have 46 chromosomes in each of the cells of our organs. These are organized into two sets of 23 chromosomes.

Each human gets 23 chromosomes from their mom, and 23 chromosomes from their dad. This is why almost everyone has some traits they got from their parents.

By looking at the chromosomes in the cell, we can tell the gender of an unborn baby. Males have XY chromosomes and females have XX chromosomes.

These are called Sex Chromosomes. 

What is a Sex Chromosome?

How is a baby made, and what can make them boys or girls?

During sexual activity (mating), the male releases the sperm cell and the female releases the ova (female cell). Remember we said previously that the human body has 23 pairs of chromosomes? Yes, the 23rd chromosome is your sex chromosomes. Boys carry XY chromosomes and girls carry XX cromosomes. During fertilization, each parent contributes a cell each. The female always contributes and X cell (because that all she has, XX chromosome) The male contributes either an X or a Y cell. The male has no control over this, as it is purely random.

If the male releases and X chromosome, it adds to the X chromosome of the female, it forms an XX— and the gender of the baby will be a girl. If the male releases a Y chromosome and adds to the females X chromosome, it forms an XY and the gender of the baby is a boy.

In recent years, it is possible to have IVF which means In vitro fertilization. This is where the female and male cells are taken from the parents and fertilized in a lab. In IVF, it is possible to choose which sex chromosomes to fertilize. This means you can choose to have a boy or girl.

IVF issues
This technology is highly debated, because many people think that it is against nature or God to choose these things and should be left for nature to decide. What do you think too? You can debate this with your family and friends.

What is Genetic Inheritance?

To inherit something means to derive or to receive something from a previous holder. Inheritance in genetic terms, means an offspring, or child (like you) receiving certain traits, behavior or characteristics from your mum and dad. Our parents’ genes will determine what we will look like.

What is an Allele?
Sometimes, there are different forms of genes from the same person. These are called Alleles (say a-leel).

To make this easier, let us use specific examples.

Let us say you have blue eyes. It would be very likely that your mum or dad also had blue eyes. If even they didn’t, the genes in their cells have blue eye traits — which they have passed on to you.

Genes determine our eye colour. Eye genes usually come in two alleles: an allele for brown eyes and an allele for blue eyes. We all have a pair of alleles that determine our eye colour.

An individual who carries two copies of the
same allele is homozygous.

An individual who carries two different
alleles for a certain gene is heterozygous.

So here are some possibilities of eye colour below:

A person with two blue alleles will have blue eyes.
A person with two brown alleles will have brown eyes.
A person with one blue allele and one brown allele will have… Brown Eyes!

Yes, this is because brown alleles are dominant alleles. Alleles can be dominant or recessive. Sometimes, a child can have blue eyes even though their mum and dad have brown eyes. This can be possible if the child inherits both blue recessive alleles from parents, as in the genetic diagram below:

Alleles are therefore very important to study because they can also help us know what kind of genetic disease may be passed on from our parents. Alleles and genes help doctors to know if a child will inherit Sickle cell disease, Huntington’s disease, or even Cystic fibrosis from their parents.

What is genetic variation?

Individuals in a population are not exactly the same.

Each individual has its unique set of traits, such as size, color, height, body weight, skin colour and even the ability to find food.

Sometimes, offspring’s of the same parents still differ a lot among themselves. You can find that among 3 sisters, one may be very tall, the other may have dark hair and the third may have a rounded nose tip. Such differences in individuals from the same parents are called variation.

Characteristics or traits that are inherited are determined by genetic information. Some other traits like dialect or accent, scars, skin texture or even body weight may be determined by some external
or environmental factors.

These factors include
Diet
Climate
Culture
Lifestyle
Language
Accidents

Sometimes a person may not have inherited a trait, but some conditions have modified the individual to exhibits specific traits. If a child with brown eyes acquires a disease that affects his eyes and turns them yellow, that may be a diseased induced variation.

In the same vain, a child my have the tendency to be tall, but diseases and poor diet during his early years my cause him to have stunted growth.

What does cloning mean in genetics?

To clone something means to duplicate (or make an exact copy of something). Genetically, cloning is the creation of an exact copy of another organism. This means that the DNA of the cloned organism is the same as the original.

Cloning is not a new thing. For many centuries, farmers have taken advantage of asexual reproduction in plants, to produced a lot of crops. Tubers (such as potatoes) and runners are all examples of asexual reproduction and cloning.

Cloning can be natural or artificial. A good example of a natural clone in humans is when the sex cell divided itself during fertilization to produce twins.

Potato plants produce many tubers. Each tuber can grow into a new plant.
Strawberry plants and spider plants produce long stems with tiny plants on the end. These runners can produce several new plants from one parent.

In animals the process of artificial cloning is even more interesting.

Let us use a cows as an example.

Scientists can take the sperm of the male cow and egg of the female cow and fertilise them. They split the zygotes into several parts and place them into the wombs of new females to carry them. All the calves that are born will have the same DNA and traits.

Is cloning a good thing?
Many people argue that natural reproduction should not be interfered with. Even though cloning can produce animals and plants with the best or desired characteristics quickly, the individuals may be prone or susceptible to disease. The process will also lead to less variation, which is a very natural flavor of life.
What are Stem Cells?

In genetic terms, stem cells are cells in the embryo that are not specialized. After fertilization, there are two types of cells in the embryo.

Specialized cells:
These are the cells modified with clearly defined instructions or tasks. They are the cells that go on to define set things like taste, hearing, sex and the like. As they divide and grow, they do NOT change into any kind of cell. They are also called differentiated cells. They are usually modified a few days after fertilisation.

Unspecialized cells:
These are cells in the embryo (just after fertilization), usually obtained from human embryos that are a few days old and are left over from human fertility treatments. These are somewhat ‘generic cells’ and can grow into any of the about 250 cell types in the human body. This type is called Stem Cell. It is also known as undifferentiated cells.

Stem cells also come into two forms or types:
Adult Stem Cell:
These are stem cells that develop into many types of cells.

Embryonic Stem Cell:
These are stem cells that can develop in to any kind of cell.

Why are stem cells important?
Scientists use stem cells to treat people with brain diseases by making new brain cells. Some cells are used to rebuild cartilage, bones and valves in blood vessels. Stem cells technology is fairly new but looks like it will be a great scientific technology in treating many serious cells and tissue diseases including cancer.

Stem cell rejection.
If you remember, we mentioned that our DNA is unique and so are our genes. This means that stem cells from the embryo of another person is very likely to fail if used in treatment for another person. The cells will die because the body will reject it as a foreign cell.

However, if the gene or cell is cloned from your own body, there is almost a sure chance that your body will accept it, because the DNA is the same.

BIG ISSUES
Stem cells are obtained in embryos (newly fertilized cells). This means that human embryos have to be destroyed to obtain the stem cells for your treatment. Many people of religious faith believe that is not acceptable to destroy embryos, under any circumstance — and is seen as murder.

Discuss with family and friends about Stem Cell technology and how if fits within human life… is it acceptable or not? Why? 

                                                          X  .  IIIIIIIII 

                                                             FORCES  

Introduction to Forces

Forces are in play all around us. Things hanging, sitting, balancing, moving and spinning are all using some kind of force. Forces come in different forms and they all result in something.

Let us start the lesson with this short picture —

" Milly opened the fridge and brought out chilled can of soda. She slammed it, opened the soda and gulped it down. She was upset it was finished too soon and so she crushed the can in her hand and threw the empty can into the bin."

Milly applied force in many of her actions (highlighted actions). Her actions involved the use of force to lift, open, turn, move and even change the shape of something.

Force, together with its various types are applied in almost every single activity in our lives.

Pushing the shopping cart, pulling the baby stroller, lifting weights at the gym, eating and many other things involve the use of some force.


Can you think of the many ways in which you have applied a force to get results?

Forces can:
Change the direction of an object. You can pull the leash of your dog to make it change direction.

Turn things. A natural force like wind can turn the blades of a wind turbine to generate electricity.

Change the shape of something. Next time your mum makes dough for bread, watch her change the shape of the dough with the rolling pin.

In this lesson, we shall look at Forces in detail and how forces change the shape of objects, get things moving, cause moving objects speed up, slow down or stop and change the way things move.  Weight, pressure and turning moments are all the result of forces too. Ready? 

What is a force?

A force can be a push or a pull. It is not something you can see or touch, but can see it in action. Forces can be measured using a device called force meter. The unit of force is called the newton. It is represented by the symbol N. A force of 2N is smaller that 7N.

A force usually results from an interaction. The interaction can be a physical one, or a non-physical one. Forces resulting from physical interaction are called 'Contact Forces' and examples include Frictional, Tension, Air resistance and Spring force.

A force resulting from non-physical interaction is called
'Action-at-a-distance force' and examples include gravitational, electrical or magnetic force.


Measuring forces





Force meters contain a spring connected to a metal hook. The spring stretches when a force is applied to the hook. The bigger the force applied, the longer the spring stretches and the bigger the reading.

A Force diagram
A force diagram is usually used to show the forces acting on an object. An arrow, with a name, length and direction is used to represent a force.

See this example below:


In a force diagram, the longer the arrow, the bigger the force. 

 

What is Mass

Every object is made up of matter (Matter is anything you can touch physically) The more matter an object has, the bigger it is, and the more mass it has. Mass is measured in kilograms, kg, or grams, g. Things that have a big mass are harder to move, or harder to stop than objects with little mass.

Mass is how heavy something is without gravity.
This means the mass of an object is the same on
earth and in space (or other planets)

A 100gm ball will be 100kg everywhere, even on the moon. This fact is not the same for weight. The weight of an object can change at a different place, such as on the moon.


In the illustration above, notice how the mass of an astronaut remains the same, whiles his weight is smaller in moon as a result of less gravity.

Mass in NOT the same as weight. The difference is that weight is determined by how much something is pulled by gravity. If we compare two different things to each other on Earth, they will both be pulled by the same gravitational force, so the one with more matter will weigh more. 

What is Weight?

Weight is a force caused by gravity. Because it is a force, it is also measured in Newtons (N). It is the gravitational force between the object and the Earth. An object will have greater weight if it has more mass.

All over the world, people read the weight of objects with kilograms. Thats is not correct. It is done only because it is easy for people to grasp. The proper scientific unit of measurement is Newton, and it is written as N

As mentioned in the previous page, the weight of an object is the same everywhere on earth because the object is under the same pull of gravity. In Space, there is no gravity so the object will not even sit on the scale at all. Is will just stay in suspense. Technically speaking, there is no weight on the Space.

Gravity on the Moon is less and that means an object will weigh less on Moon than on earth.

An object's weight (W) can be determined by the product of its' mass (m) and the magnitude of the local gravitational acceleration (g), thus W = mg.

An object with a mass of 1 kg has a weight of about 10 N, everywhere on earth.

Apparent weight
Sometimes the scale can record the weight of an object and get it wrong. Here is a simple test: The next time you stand on a scale, you will notice that your weight will be slightly more if you try to jump on it. This is because you put more force downwards, in addition to original force of of gravity. This is apparent weight and it is a measure of downwards force, not the weight from gravity.

What is Gravity

All objects have a force that attracts them towards each other. This force is called gravity. Even you, attract other objects to you because of gravity, but you have too little mass for the force
to be very strong.

Gravitational force increases when the masses are bigger and closer. This means that the gravitational force on Moon is less than on earth, because Moon has less mass than Earth.

Good examples of very massive objects that possess gravitational force include the moon and other planets. Consider the earth on which humans live. Everything tends to fall on the ground and stays there. If you jump, you came down again. Throw a ball upwards, and it will surely come down.

"Down" is towards the centre of the Earth, wherever you are on the planet.

This is a result of gravitational force, which pulls objects towards the center of the earth.

Pressure

Pressure depends on how much force or weight is exerted, and over the area on which that force is applied: greater force, more pressure.

This is the equation for working out pressure:
pressure = force ÷ area

The unit for pressure is pascal, Pa. Pa is the same as newtons per square metre N/m2 . 1 Pascal = 1 N/m2.

Let us see some classic examples of pressure.

Drawing pins
If you held a drawing pin and pressed the pin the wrong way, what will happen? You surely will hurt yourself.

In the illustration above, there is more pressure at the pointed part of the pin, because that area is tiny and given the same force, the pressure will be more. The pressure at the flat end is less because the area is wider.


High-heel shoes
Take a look at these two shoe types. If a lady wearing the high heel shoe stepped on your feet with her heels, that would almost punch a hole because of the heels little area. It would be less painful if she wore the flat pinky shoe because the sole are is larger and the pressure is less. 








Balanced forces

Balance forces are two forces acting in opposite directions on an object, and equal in size. Anytime there is a balanced force on an abject, the object stays still or continues moving continues to move at the same speed and in the same direction. It is important to note that an object can be in motion even if there are no forces acting on it.

Balanced forces can be demonstrated in Hanging, Floating and Standing/sitting objects

Hanging objects
Take a look at this hanging glass bulb shade. The weight of the bulb shade pulls down and the tension in the cable pulls up. The forces pulling down and pulling up can be said to be in balance.











Floating objects

Take a look at this log floating on a pool of water. It is floating because the weight of the log is balanced by the upthrust from the water. If more weight is tied to the log, the force pulling it down may be more and will cause it to sink.


Standing/Sitting on a surface
Consider a metal block resting on a surface of a table. Its' weight is balanced by the reaction force from the surface. The surface pushes up against the metal block, balancing out the weight (force) of the metal block.

Unbalanced forces

Unlike balanced forces, we say unbalanced forces when two forces acting on an object are not equal in size.

Unbalanced forces causes can cause:
a still object to move
a moving object to speed up or slow down
a moving object to stop
a moving object to change direction

Unbalanced forces make the wagon in the diagram speed up.

Notice that because there is a bigger force and a smaller force involved, the direction of the wagon will be determined by the bigger force. The wagon is moving as a result of unbalanced forces. 

     

Resultant forces

To understand resultant forces better, let us see these two scenarios:

Any time a stationary object stays still, its' resultant force is zero. As soon as force is applied, acceleration begins. The speed of the acceleration will depend on the force applied and the mass of the object.

In a similar way, each time an object in motion (in constant speed and same direction) stays in motion, its' resultant force is zero too. As soon as a force is applied, it can make it stop, change direction, move slower or move faster. The resulting effect will depend on the force applied and the mass of the object.

It is worth noting that an object may have several different forces acting on it. See example in the illustration below:

All these different forces, F1, F2, F3 can be added up to know the resultant force, F4. The resultant force is the single force that has the same effect on the object as all the individual forces acting together.

If different forces are acting in different directions, a resultant force can be determined as well. See illustration below:

Notes
If the resultant force acting on a stationary object is zero, the object will remain stationary.

If the resultant force acting on a moving object is zero, the object will carry on moving at the same speed in the same direction (i.e. at constant velocity).  


Frictional forces

Friction is a force that stops things from moving easily.

Whenever an object moves or rubs against another object, it feels frictional forces. These forces act in the opposite direction to the movement. Friction makes it harder for things to move.

In the illustration below, the smooth base of the snoblades slides smoothly on the snow. The boy on the grass is having difficulty sliding, because the grass is not smooth and his shoes are getting stuck in the grass. There is more friction between the shoes and the grass than the snow and the snowblades.

Without frictional forces, a moving object may continue moving for a longer period. Frictional forces are usually greater on rough surfaces than on smooth surfaces.

Frictional forces can be good and helpful. For example:

A basketball star can grip a ball and control it better in a dunk because of greater friction.
When we walk, we don’t slip easily because of the friction between our shoes and the floor.
Each time you ride your bike, friction between the tires and the road help you not to skid off.

Sometimes frictional forces can be unhelpful.
If you don't lubricate your bike regularly with oil, the friction in the chain and axles increases. Your bike will be noisy and difficult to pedal.


Air resistance

Moving objects like aircrafts, cars and arrows experience air resistance when they are in motion. Frictional forces of the air against the moving object cause this resistance. There is more (bigger) resistance with faster movement, and less resistance with slower resistance.

Cars, aeroplans and many fast moving objects are usually streamlined to overcome resistance.

Have you seen bike riders in a race? They wear smooth clothing and helmets designed to overcome resistance. This makes them glide through the air with top speed.

Moments

Moments is a scientific name for turning forces around a pivot. Forces can make objects turn if there is a pivot. Take a look at the illustration below. The pivot is the point in the middle of it. This pivot make one end tip up or down depending on the force applied to one end. This means moments can be equal and opposite if the force applied at both ends are equal and the sea-saw is balanced.

To work out a moment, two things are considered:
The distance from the pivot that the force is applied.
The size of the force applied

This is the equation for working out a moment:
moment = force × distance
The unit for moment is Nm (newton metre).

Example
If a force of 10 N acted on a see-saw 2 m from the pivot, moment would be worked as follows:

force × distance = moment
10 × 2 = 20 Nm

Here is an example of balanced moments. 20N at 4m from the pivot is balancing 40N at 2m from the pivot. The objects create moments of 80Nm that are equal and opposite, so the see-saw is balanced.


Equal Moments balances out a see-saw


Moments can be useful in many ways. Here are a few examples

A crowbar uses moments to lift heavy things over a lever. See the diagram below

You will notice that longer spanners undo nuts a lot more easily than shorter spanners. See the illustration below

A see-saw will balance if the moments on each side of the pivot are equal. This is why you might have to adjust your position on a see-saw if you are a different weight from the person on the other end.




                                                        X  .  IIIIIIIIII 
                                                GENETIC ENGINERING 


Introduction to genetic engineering.

You may have heard that many foods (plants and animals) these days have questions around them, as to whether they have been grown naturally or have been manipulated in some way. These are genuine concerns as biotechnology has entered into new areas where DNAs of plants and animals have been combined to create new DNAs that never existed.

It is VERY important to understand what DNA and Gene is. DNA simply means Deoxyribonucleic Acid. It is a hereditary molecule that is found in almost all living things (cells). DNA carries a code (information) that genes use to make living things grow. It is found in all cells in structures called chromosomes.

Genes are instruction manuals in our body. They are molecules in our body that explain the information hidden in our DNA, and supervises our bodies to grow in line with that information. With that brief DNA and Gene explanation, let us see this scenario.

A scientist wants to make blue apples:
The scientist decides on the intent or reason for making blue apples. He can get a plant with blue fruits (say blue berries). He cuts out a piece the blueberry DNA and inserts it into the apple’s DNA. He plants the new apple seed and the apple tree produces blue apples instead of red.

But it is not plants alone — if he wants a cow to have some desired traits such as high milk production, he can get the DNA of a cow with that trait and fix its DNA into the new cow, so that the recipient cow will have a high milk production trait.

Some time back farming practices like Simple Selection, Crossing, Interspecies Crossing, Embryo Rescue and Cell Selection were used to propagate crops and animals with better qualities. The concept is what drives genetic engineering today.

It is worth knowing that biotechnology or genetic engineering has the capacity to manufacture entirely new animals or plants, from merging cells from different sources. It can get a bit scary on the face of it, but in this lesson, we shall look at what the real issues are, in terms of foods that we eat.

It is important that you read about DNA and GENES . 

What is genetic engineering or genetically modified organisms (foods)

The words Genetically Modified Organisms(GMO), Genetically Engineered (GE) and Biotechnology are often used interchangeably, but Genetic modification is simply the addition of new DNA to an organism or living thing, thereby modifying its genetic make-up.

It is the use of modern biotechnology (or gene technology) tools to introduce new traits (characteristics) into organisms, either from related and non-related organisms.

For example, a DNA from a plant (Plant X) that has high resistance to pests can be copied and introduced (added) to another plant (Plant Y), so that, the Plant Y will have the pest resistant trait.

Note that the DNA of an organism (e.g fish) can be modified by a DNA from a plant, which is a completely non related organism.

Another example is that, sometimes chemicals used in farming, such as herbicides end up killing lots of the crops planted, together with the weeds. Here, DNA from a herbicide resistant plant can be copied and added to the cells of the food crop so that the food crop will withstand herbicides when they are applied to the crops.

The concept of genetic engineering in not new, in fact it has been used to produce many blood, milk, lab mice types for research and pharmaceutical purposes for many years now. In recent time, the technology has been applied to plants and animals for food purposes, and that is why the argument has heated up.



You may not be able to tell a genetically modified fruit (e.g. strawberry) from its natural counterpart. They may look the same, but their cell DNA make-up will be different. Both fruits come from strawberry shrubs, but the shrub of the GM fruit would have produced fruits in a relatively shorter time period, or the GM fruit may have some toxin DNA in it which made it resistant to pests and diseases. 

 

GM and cloning: what is the difference?

Cloned animals are different from Genetically Modified (GM) animals, even though they are all results from the tools of biotechnology.




Genetic Modification (GM)

This introduces new genes into an organism. That means the recipient organism’s genes are now different from its parents genes (or from its original genes). When that new organism has offsprings, they are NOT clones. They are offsprings that will carry the new genes that were introduced to the parent. The new offsprings will also pass on that gene to new generations of offsprings. The entire line of generations, from the originally modified organism will all be called GM animals.

Cloning

Cloning is very different. To clone something means to duplicate (or make an exact copy of something). Genetically, cloning is the creation of an exact copy of an organism. This means that the DNA or genes of the cloned organism is the same as the original.

For example, a scientist can a take female egg cell of a pig and fertilise it with a male sperm cell of a pig. At the fetilised-egg (zygote) stage, he can duplicate the zygote into 5 or 6 zygotes and place them into different female pigs to carry until they are born. All 6 of the piglets will have the same DNA even though they were birthed by different mothers. All 6 piglets can be called clones.

Cloning is a very common process in plants too. For example, if you plant from the cuttings of a crop, you are reproducing by asexual means. With cloning, no new genes are added. It is important to remember that a cloned animal was born by asexual reproduction, not sexual reproduction. 

  

Why do we need gmo?

The developers of GM foods believe that genetically modified organisms will have lower prices, higher nutritional value and taste, and durable in terms of produce quality. More importantly, they believe that the plants will be more resistant to droughts, pests and weeds. Earlier, the main aim was to increase crop protection, but its perceived success has empowered the developers to explore into new areas of modifying organisms to yield even more radical results.

Some organisms are constantly being attacked by pests and some insects, and traditional methods of fighting them are just too costly and painful. So just like a flu shot, researchers believe the DNA from a virus can be fixed into the DNA of the crop, and make it more resistant to that virus.



Before we look at the arguement for and against this technology, here are a few reasons why GM foods are produced: to be insect resistant, virus resistant, and/or herbicide tolerant.

To this end, scientists have:
Introduced genes for toxin production into crops, making the crops require less insecticides on the lands on which they are planted

Introduced genes from some viruses into the crops, thereby making them less susceptible to diseases and therefore increasing its produce

Introduced some genes from some bacterium that makes the crops resistant to some herbicides.

The net resuls for all of this, is increased crop yield and higher production. 

Genetic engineering debate:

Uncertainty
The biggest worry in GMO technology perhaps is the uncertainty surrounding it. Many people feel that we may be going onto an area that we cannot control if it gets out of hand. Maybe it is too late now, because we have all (very likely) already consumed lots of GM foods. Whiles there is little research on the real effects of GMO on human health, it is widely known that GM foods are safe for consumption, at least in the short term. The debate is a very heated one.

Food redistribution and food waste
People speaking against GMO have a different point of view. They argue that feeding the worlds hungry and malnourished can be achieved by redistribution of food supplies. They argue that there is a lot of food waste in many of the countries that are pushing for GMO. If they really did care, they could invest in cutting the waste and distribute the surpluses to the most needed places. That sounds great, but is that possible?

Transfer of allergenic genes
Some people react to some food types. Transferring allergenic genes can result in contamination of natural foods and open up the range of allergic foods for people. For example, an allergenic Brazil-nut gene was inserted to a transgenic soya bean variety, but luckily the effect was noticed before it was released into the market.
— Source: Weighing the GMO arguments. FAO

Environment
There is also concerns about the environment. The use of heavy chemicals on crops means that the land will absorb the chemical residue. Weeds that were killed will contain chemical residue, posing a threat to soils and living organisms in them.

Food supply
Hundreds of millions of people in the world are malnourished and hungry. Where is the food going to come from if we depend on natural farming practices that we have used all along? Many people speaking for the use of GMO say that the technology will make farmers in developing world (and all over the world) combat drought, pests and weeds more effectively and increase yields at local levels. Local farmers will need less effort to produce a higher yield.
   

                                                            X  .  IIIIIIIIIII   

                                                       Earthquakes & Tsunamis 

 Introduction to Earthquakes & Tsunamis

Turn on the TV or read the newspapers and almost always there is something devastating happening somewhere as a result of sheer nature's power. Examples of such natural occurrences are hurricanes, tornados, wildfires, volcanic eruptions, flooding, earthquakes and tsunamis. These are usually not caused directly by humans, but their effects live with us for a long time. In this lesson we shall look at one of such natural occurrences...earthquakes!


What is an Earthquake?

Simply, earthquakes are the rumblings, shaking or rolling of the earth's surface. It is usually what happens when two blocks of the earth suddenly slip past one another, or break apart from each other as a result of tension caused by prolonged energy build up.

   

Earthquakes come in many forms. It can be felt as a shock under your feet, or may be very powerful and destructive enough to flatten an entire city. They can happen anywhere, land or sea.

Foreshocks, Mainshocks and Aftershocks:
Sometimes, there are smaller shocks that occur before (foreshock) and after (aftershock) a main earthquake (mainshock). Sometimes foreshocks are so big and scientists are unsure if it is the main shock. Foreshocks and aftershocks can occur for days, weeks and months of a main earthquake.

Earthquakes are also called temblors.

It is important to understand
the earth’s makeup to help understand earthquakes better.

In this diagram, you will notice that the inner and outer core of the earth (middle part) are liquid in nature, containing iron and nickel of extreme temperatures (5,500°C).

The Mantle is semi-molten rock, also called magma. The outer is the crust, which is the hard part of the earth that forms the surface. This outer crust includes the land on which we live, the oceans and ocean deeps and anything within 40km (approx) down the earth's surface.

Earthquakes are developed in the outer crust of the earth. 

Important terms to know about earthquakes

Let us take a moment to learn about these terms to help us understand earthquakes better.

Tectonic Plates:
These are huge layers that make up the earth’s upper layers. They continually stretch, move, slide, and collide against each other. Even though they are constantly moving, we do not feel it. Each plate is about 50 to 250 miles (80 to 400 km) thick.

Faults (or Fault plane or fault lines):
These are weak lines that can develop in the plates, usually on the surface of the earth. There are different types of faults and the major types include dip-slip normal, dip-slip reverse, strike-slip and oblique-slip.
The hypocenter is the location below the earth’s surface where the earthquake starts. The epicenter is the location directly above it on the surface of the earth.

Seismograph and The Richter Scale (RS):
The seismograph is a device that scientists use to measure the magnitude of an earthquake. The Richter scale on the other hand is a scale or measure that is used to compare earthquakes. It is calculated in levels of ten. Example, an earthquake measuring 4 on the RS is ten times more than a measurement of 3, and an earthquake measuring 8 on the RS is 10 times more than one that measured 7 on the RS. As a guide, an earthquake measuring 3-5 is considered minor, 5-7 is moderate, 7-8 is major, and 8 or more is considered great and usually very devastating.

Ring of Fire:


This is the coastal belt of the Pacific Ocean (see diagram) which is the home of many volcanic eruptions, plate movement and major fault lines. About 90% of the world's earthquakes and 81% of the world's largest earthquakes occur along the Ring of Fire. The Ring of Fire is a direct result of plate tectonics and the movement and collisions of lithospheric plates. 


 
Earthquakes develop in the crust of the earth. The crust involves the earth's surface, submarine levels, down to the ocean floors. The inner part of the earth contains massive energy. Some of this energy escapes through cracks and other volcanic activity, but the bulk of it is stored within the earth’s inner part, contained in the crust.

The earth’s outer crust is held in place like a completed jigsaw puzzle, with rough edges and lines. The energy stored here causes the pieces to slide, glide, knock and move around each piece. These pieces best describe what we call ‘Tectonic plates’ (See illustration below)

After a period of time, the built up energy and movement causes huge tension in the plates, and there is massive pressure on the fault lines. This intense pressure resulting from energy build up causes the fault lines give way, and plates move over, against or apart from each other.

It is important to note that there is usually a very thick natural cover (earth and vegetation) which makes fault lines obscure.

There is an earthquake at this point. In the form of seismic waves (like water ripples) the escaping energy radiates outward from the fault in all directions. The seismic waves shake the earth as they move through it. When the waves reach the earth’s surface, they shake the ground and anything on it, tearing down houses and structures.  

What are the types of earthquakes?

Earthquakes can come in three main forms, depending on the plate movements that occur beneath the earth's surface. They could occur on a Convergent Boundary, Divergent Boundary or a Transform Fault.

Convergent boundary:
Here, one plate is forced over another plate during movement creating a thrust fault.

Divergent boundary:
Here, plates are forced apart each other, usually forming a Rift Zone. This kind is common in ocean floors where new floors are created. An example is the Mid Atlantic Ridge.

Transform fault:
Unlike divergent and convergent, the plates here slip by each other. This is also called Strike-Slip.

Earthquake Waves
There are 2 types of earthquakes waves and the difference lies in the way the seismic waves are transmitted. To understand this better, let us see what a seismic wave is.

These are waves of energy that travel through the earth's layers, and other elastic layers, often as a result of earthquakes. A wave, by general definition is the transfer of energy from one place to another without transferring solid, liquid or gas matter. Examples include light and sound waves.

During an earthquake, the waves released may be “P” or “S” waves depending on the speed and ways in which they travel.

P-Waves (Primary Waves)

P-waves are longitudinal in nature. The vibrations are along the same direction as the direction of travel. It is also known as compressional waves. P-waves travel faster than S-waves.

S-Waves (Secondary waves)

Here the waves travel at right angles to the direction of travel. They are also known as transverse waves and example include water waves.

With this in mind, you will notice that if you are close to the point where an earthquake struck, you will feel both P and S waves close within the same time frame. If you are further away, you will feel the P-wave first and then the S-wave a bit later.

Both waves can be destructive, but their study helps us to know where the earthquake struck. 

What is a Tsunami?

This is simply a series of massive ocean waves, triggered by an earthquake that has occurred in the sea (or ocean). The displaced water then runs ashore and into the land. This happens when the plates underneath the Earth's surface move (focus) so that one slips under another.

Tsunamis may also be caused by underwater landslides or volcanic eruptions.

Water level can rise as high as 100ft, even though it can look like only a foot or two from above. The water moves at incredible speed (500 miles per hour) towards land, with phenomenal destructive power. The speed of the water picks up as it travels.

Tidal waves differ from tsunamis. Tidal waves are usually in circular motion. Tsunamis are a lot different. The water moves with a flat surface and has a lot of speed and power.

Researchers believe that most tsunamis, (80%), happen within the Pacific Ocean’s “Ring of Fire,” a geologically active area where tectonic shifts make volcanoes and earthquakes common.

During a tsuname, your best bet for safety is to move to higher ground.  

Preparing for an earthquake

Predicting when an earthquake will strike is one thing that scientists have not figured out yet. Scientists know that they happen along fault lines and we know where these fault lines are.
There are things we can do in preparation for them, and to make the response easier and quicker when they do.

Governments:
Authorities need to educate people about earthquake prone areas and fault lines in the country. People must also be educated about what earthquakes are and how to respond to them when they occur.

Proper building permits and approvals must be given before people build in these areas. There are good engineering and architectural practices that can be engaged to put up earthquake-proof buildings.

Governments must ensure that facilities like fire and police stations, hospitals, schools and shelters, and emergency command posts are working well and prepared to deal with an emergency. In many countries, these facilities are legal requirements.

Individuals:
Know your environments and buildings. It is important that you know where you live and where you visit often. If this is an earthquake prone region, be sure you know about your building (home, school, work places) always keep in mind what you can do if an earthquake starts.

During an earthquake, try to get away from objects that will fall or break. Run for cover under a sturdy piece of furniture.

Move into the open if this is possible. Go out of the building if possible, as the building can cave in.

There are usually aftershocks hours, days and months after a main earthquake. Try to be on your guard and look out for it.

Learning what actions to take can help you and others to remain safe and healthy in the event of an earthquake. Sufficient preparation, planning and drills are required if societies can survive the occurrence on an earthquake. Far in advance, ensure you have enough emergency supplies at home, office and schools. Identify and reduce possible hazards in your home, and practice what to do during and after an earthquake.  

Earthquakes and Tsunamis... Did you know?

Scientists can locate the epicenter of an earthquake by studying the different speeds of seismic waves.

In modern architecture and engineering, buildings can be constructed to be earthquake—proof. They are built to sway and stand after the waves run through the earth’s surface. This is particularly useful in areas know to be earthquake prone. Even if they fall, there will be less damage to life and property.

The world’s earliest recorded earthquake occurred on January 23, 1556 in Shaanxi, Central China. It had a magnitude of 8.0, and an estimated 830 people were killed. Many people there lived in caves dug into soft rock and these collapsed during the earthquake.

Himalaya-Karakoram is believed to have been created y the movement of Tectonic plates. This land mountain range is the greatest in the world. It has 96 of the world’s 109 peaks of over 7,317m (24,000 ft approx), with the longest range in the Andes of South America, which is 7,564km (4700 mi) in length.

The largest recorded earthquake in the world was a magnitude 9.5 (Mw) in Chile on May 22, 1960.

The East African Rift System is a 31-37 miles wide zone of active volcanics and faulting that extends north-south in eastern Africa for more than 3000 km (1864 miles) from Ethiopia in the north to Zambezi in the south. It is a rare example of an active continental rift zone, where a continental plate is attempting to split into two plates which are moving away from one another. earthquake.usgs.gov

Faults were first recognized as the source of earthquakes in 1855. Before that, the first “pendulum seismoscope” was developed in 1751 to measure the shaking of the ground during an earthquake.

A tsunami and a tidal wave are two different things. A tidal wave is caused by the earth’s movement and interactions between the sun and moon. It is usually very shallow water and very mild. A tsunami is a sea wave caused by an underwater earthquake or landslide. It is usually triggered by an earthquake, and results in displacing the ocean water, throwing it ashore and into the land. 

Earthquakes events in recent time.

The greatest earthquake in history occurred in Chile, 1960 May 22 19:11:14. It had a magnitude of 9.5 and approximately 1,655 were killed, 3,000 injured, 2,000,000 homeless, and $550 million damage in southern Chile. Researchers believe that there would have been more deaths and damage if theta had happened in recent time, where the population is higher are more people living in closer proximity.

On Tuesday, January 12, 2010, another earthquake measuring 7.0 with an epicenter 16 miles west of Port-au-Prince, Haiti struck, killing over 100,000 people and affecting over 3 million others. The government of Haiti estimated that 250,000 residences and 30,000 commercial buildings had collapsed or were severely damaged.
Wikipedia, 2010 Haiti Earthquake.

April 11, 2012, an earthquake of magnitude 8.6 struck the Indonesian Province of Aceh. It is believed that 5 people died as a result of this earthquake.

On Friday 11 March 2011, The T?hoku earthquake and tsunami struck with a magnitude of 9.0. It is believed to be the most powerful earthquake that ever hit Japan, with over 15,000 deaths, 3,000 missing, and over 120,000 buildinsg flattened. This earthquake also caused extensive damage to roads, dams, and many huge power and water installations.

Earthquakes and tsunamis cause the greatest mortality, with the 2004 Indian Ocean Tsunami accounting for around 230,000 deaths. On top of its huge impact on life, the Indian Ocean Tsunami made 1.5 million homeless, whilst the 2005 earthquake in Pakistan killed 86,000 people and left millions homeless. While the Indian Ocean Tsunami reduced Indonesia’s GDP growth only marginally, by 0.1 to 0.4 per cent, the hardest hit province of Aceh lost capital stock equivalent to 97 per cent of its GDP.

An earthquake of magnitude 7.7 struck southwest Pakistan on Tuesday, 24th September 2013, killing more than 327 and injuring hundreds more. Reports indicated that houses were flattened. The same earthquake caused a thrust up our of the sea, forming a small island of about 20-30ft high and about 100ft in diameter.

Research:
Has your country or city experienced an earthquake before? We do not wish that to happen, but it is important to know if your city is along a fault line, or if your city is prepared for natural occurrences like this. 


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                                                                          Flooding  





Introduction to Flooding

Many of us have this idea that floods (or flooding) is simply, too much water around your house. People think that can be fun. Wrong. Flooding is a lot more than that.

Flooding is extremely dangerous and has the potential to wipe away an entire city, coastline or area, and cause extensive damage to life and property. It also has great erosive power and can be extremely destructive, even if it is a foot high.

What is a flood?

It is a natural event or occurrence where a piece of land (or area) that is usually dry land, suddenly gets submerged under water. Some floods can occur suddenly and recede quickly. Others take days or even months to build and discharge.

When floods happen in an area that people live, the water carries along objects like houses, bridges, cars, furniture and even people. It can wipe away farms, trees and many more heavy items.


Floods occur at irregular intervals and vary in size, duration and the affected area.

It is important to note that water naturally flows from high areas to low lying areas. This means low-lying areas may flood quickly before it begins to get to higher ground.

In this lesson, we shall see more about what causes flooding, the types of flooding, some effects of floods and what we can do before, during and after floods occur.



What causes flooding?

Here are a few events that can cause flooding:



Rains
Each time there are more rains than the drainage system can take, there can be floods. Sometimes, there is heavy rain for a very short period that result in floods. In other times, there may be light rain for many days and weeks and can also result in floods.

River overflow
Rivers can overflow their banks to cause flooding. This happens when there is more water upstream than usual, and as it flows downstream to the adjacent low-lying areas (also called a floodplain), there is a burst and water gets into the land.

Strong winds in coastal areas
Sea water can be carried by massive winds and hurricanes onto dry coastal lands and cause flooding. Sometimes this is made worse if the winds carry rains themselves. Sometimes water from the sea resulting from a tsunami can flow inland to cause damage.

Dam breaking (raptured dam or levee) (Embankments, known as levees, are built along the side of a river and are used to prevent high water from flooding bordering land)
Dams are man-made blocks mounted to hold water flowing down from a highland. The power in the water is used to turn propellers to generate electricity. Sometimes, too much water held up in the dam can cause it to break and overflow the area. Excess water can also be intentionally released from the dam to prevent it from breaking and that can also cause floods.
February 26, 1972 - Buffalo Creek Valley, West Virginia 
The failure of a coal-waste impoundment at the valley’s head took 125 lives, and caused more than $400 million in damages, including destruction of over 500 homes.  

Ice and snow-melts
In many cold regions, heavy snow over the winter usually stays un-melted for sometime. There are also mountains that have ice on top of them. Sometimes the ice suddenly melts when the temperature rises, resulting in massive movement of water into places that are usually dry. This is usually called a snowmelt flood

Types of floods

Some would like to see the causes of floods as types of floods, but on this page we shall look at three major flood types: Flash floods, Rapid on-set floods and Slow on-set floods.

Flash floods
This kind occurs within a very short time (2-6 hours, and sometimes within minutes) and is usually as a result of heavy rain, dam break or snow melt. Sometimes, intense rainfall from slow moving thunderstorms can cause it.  Flash floods are the most destructive and can be fatal, as people are usually taken by surprise. There is usually no warning, no preparation and the impact can be very swift and devastating.



Rapid on-set floods
Similar to flash floods, this type takes slightly longer to develop and the flood can last for a day or two only. It is also very destructive, but does not usually surprise people like Flash floods. With rapid on-set floods, people can quickly put a few things right and escape before it gets very bad. Slow on-set floods
This kind is usually as a result of water bodies over flooding their banks. They tend to develop slowly and can last for days and weeks. They usually spread over many kilometers and occur more in flood plains (fields prone to floods in low-lying areas). The effect of this kind of floods on people is more likely to be due to disease, malnutrition or snakebites.  

 
Which areas are more likely to flood?

From the causes of floods and the types that we just read about, you can tell that floods are more likely to occur in some areas than others.

Generally, the natural behavior of water (and flowing water) is that it moves from higher ground to lower ground. This means if there is a higher ground adjacent a lower ground, the lower ground is a lot more likely to experience floods.

Additionally, anywhere that rains fall, floods can develop. This is so because anytime there are more rains bringing more water than it can be drained or absorbed by the soil, there is a flood potential.

In many cities, there are buildings springing up in many places where they have not been authorized. Some of these building are placed in waterways.  Other places also have very bad and chocked drainage systems. The danger is that, with the rains, water will find its own level if it cannot find its way. The result is flooding and your home could be under water.

Any plain low-lying area adjacent a river, lagoon or lake is also more likely to have floods anytime the water level rises. This includes coastal areas and shorelines, as seawater can easily be swept inland by strong winds, tides and tsunamis. 

 
Effects of flooding

Floods can have devastating consequences and can have effects on the economy, environment and people.

Economic
During floods (especially flash floods), roads, bridges, farms, houses and automobiles are destroyed. People become homeless. Additionally, the government deploys firemen, police and other emergency apparatuses to help the affected. All these come at a heavy cost to people and the government. It usually takes years for affected communities to be re-built and business to come back to normalcy.
Did you know that the cost of all floodings in the USA in 2011 was $8,640,031,956 (approx 8.5B USD) — http://www.nws.noaa.gov/hic/

Environment
The environment also suffers when floods happen. Chemicals and other hazardous substances end up in the water and eventually contaminate the water bodies that floods end up in. In 2011, a huge tsunami hit Japan, and sea water flooded a part of the coastline. The flooding caused massive leakage in nuclear plants and has since caused high radiation in that area. Authorities in Japan fear that Fukushima radiation levels are 18 times higher than even thought.

Additionally, flooding causes kills animals, and others insects are introduced to affected areas, distorting the natural balance of the ecosystem.

People and animals
Many people and animals have died in flash floods. Many more are injured and others made homeless. Water supply and electricity are disrupted and people struggle and suffer as a result. In addition to this, flooding brings a lot of diseases and infections including military fever, pneumonic plague, dermatopathia and dysentery. Sometimes insects and snakes make their ways to the area and cause a lot of havoc.

...But...
There is also something good about floods, especially those that occur in floodplains and farm fields. Floodwaters carry lots of nutrients that are deposited in the plains. Farmers love such soils, as they are perfect for cultivating some kinds of crops. 

What you can do before during and after floods.

Sometimes there is no warning of flash floods, and that is why it is important to think of them and prepare for them before they happen. Here are a few things you can do.

Before the floods...
1. Know about your local relief centers and evacuation routes.
2. Keep emergency numbers and important information handy, as well as emergency supplies, kits, first aid items. These may include water, canned food, can opener, battery-operated radio, flashlight and protective clothing.
3. Fold and roll up anything onto higher ground (or upper floors of your home), including chemicals and medicines.
4. Make sure everything that is of importance is secured (jewelry, documents, pets, and other valuables).
5. Plant trees and shrubs and keep a lot of vegetation in your compound if you are in a low-lying area as that can control erosion and help soften the speed of the flowing water.

During the floods...
1. Flash floods occur in a short spate of time. As soon as they start, be quick, keep safe and ensure that children and elderly are safe by leaving the house to a higher ground.
2. Turn off all electrical appliance, gas, heating and the like if there is a bit of time.
3. Leave the area before it gets too late. Do not drive through the water as moving water can sweep you away.
4. Stay away from power lines or broken power transmission cables.
5. Try to keep away from flood water as it may contain chemicals or other hazardous materials.

After the floods...
1. Make sure you have permission from emergency officers to get back inside your house.
2. Keep all power and electrical appliance off until the house is cleaned up properly and an electrical personnel has confirmed that it is OK to put them on.
3. Make sure you have photographs, or a record of all the damage, as it may be needed for insurance claims.
4. Clean the entire home, together with all the objects in it very well before you use them again. They may be contaminated.
5. Wear appropriate gear (mask and gloves) before cleaning begins.

  

Methods of flood prevention

Humans cannot stop the rains from falling or stop flowing surface water from bursting its banks. These are natural events, but we can do something to prevent them from having great impact. Here are a few.

Sea / Coastal Defence Walls

Sea walls and tide gates have been built in some places to prevent tidal waves from pushing the waters up ashore. In some areas too, sand bags are made and placed in strategic areas to retain floodwaters.

Retaining walls
In some places, retaining walls levees, lakes, dams, reservoirs or retention ponds have been constructed to hold extra water during times of flooding.

Town planning
It is important that builders acquire permission before buildings are erected. This will ensure that waterways are not blocked. Also, drainage systems must be covered and kept free from objects that chock them. This way, water can quickly run through if it rains and minimize any chance of town flooding. Drainage systems should also be covered to prevent litter from getting into them.

Vegetation
Trees, shrubs and grass help protect the land from erosion by moving water. People in low-lying areas must be encouraged to use a lot of vegetation to help break the power of moving flood water and also help reduce erosion.

Education
In many developing countries, drainage systems are chocked with litter and people have little knowledge of the effects that can have during a rain. When it rains, waterways and culverts are blocked by massive chunks of litter and debris, and water finds its way into the streets and into people's homes. Education is therefore very important, to inform and caution people about the dangers of floods, what causes floods, and what can be done to minimise its impact.

Detention basin
These are small reservoirs built and connected to waterways. They provide a temporary storage for floodwaters. This means in an event of flooding, water is drained into the basin first, giving people more time to evacuate. It can also reduce the magnitude of downstream flooding. 

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                                                                              Tornadoes  

How do Tornadoes form?

This question is one that has not been a bit uncertain among people who study weather, but here is an explanation that many believe is the closest possible cause of tornadoes.

Tornadoes are simply borne out of supercell storms (Supercell tornadoes are more powerful than those that do not come from supercells). A supercell storm is a thunderstorm characterized by powerful updrafts. Example of non-supercell tornadoes are ‘gustnadoes’ and ‘landspouts’.

Here is how they form:
Take a look at this illustration and find the notes below.

Step 1: Like all winds and storms, tornadoes begin when the sun heats up the surface of the land. As the warm, less heavy air begins to rise, it meets the colder, heavier air above it. Note that wind shears make it even easier to set them off. A wind shear is when two winds at different levels and speeds above the ground blow together in a location.

Step 2: The faster moving air begins to spin and roll over the slower wind. As it rolls on, it gathers pace and grow in size.

Step 3: At this stage, it is an invisible, horizontal wind spinning and rolling like a cylinder. As the winds continue to build up, stronger and more powerful warm air forces the spinning winds vertically upward, causing an updraft.

Step 4: With more warm air rising, the spinning air encounters more updraft. The winds spin faster, vertically upwards, and gains more momentum.

Step 5: At this stage, the spinning winds, creates a vortex and the wind has enough energy to fuel itself.

Step 6: The tornado is fully formed now and moving in the direction of the thunderstorm winds. When the pointed part of the tornado touched the ground from the cloud, it is often referred to as 'touch down' As it moves it rips off things along its patch. 


Profiles of Tornadoes

In the first page, we mentioned an average of 800 tornadoes in the USA occurring every year. How come we do not hear of each of them? It is because they come differently in terms of their destructive power. There are 6 categories of tornadoes, scaled from F0 up to F5, and is measured with a scale called The Fujita Tornado Damage Scale. Here are the descriptions, in terms of the damage it does: F0—LIGHT: These come as strong winds, with little damage to roofs that are poorly maintained. These winds can displace light-weight objects such as trash cans. They occur very often, making up about 60% of the total number of tornadoes in the year.

F1—MODERATE: These make up about 28% of the total number of tornadoes. They cause minor damage to landscape, young trees, building roofs and break windows. They can displace heavier objects.

F2—CONSIDERABLE: These make up about 9% of the total number. They break tree branches and bend trees. They cause considerable damage to property as a result of airborne debris. They can move and displace a garden shed with poor foundations.

F3— SEVERE: These can uproot trees and break walls of buildings. They can rip off roofs and cause severe damage. These make up about 3% of the total number of tornadoes, and their destruction usually make it to the news on TV.

F4—DEVASTATING: These are pretty destructive, as small cars are blown over and displaced. Well constructed homes are broken, trees are uprooted and blown away. They carry heavy debris and destroy anything in its path. They make up only about 1%.

F5 d—INCREDIBLE: These make up less than 1% in number. They are so powerful that they flatten pretty much any structure in its path. Mature trees are left with no branches, others are uprooted and blown away, and automobiles are significantly blown away and displaced.

After a while, the funnel shape of the tornado thins out as it reaches the end of its life, looking like a rope. This is called the rope stage. 


The impact of Tornados

Like all natural disasters such as hurricanes, earthquakes, floods and others, they end up with massive destruction to homes, property, infrastructure and cause many deaths as well. Each year, about 60 people are killed by tornadoes, mostly from airborne debris. Source: noaa.gov. This means individuals, families, communities and the government are all affected in one way or the other.

Here are a few examples:

April 25-28, 2011, USA:
More than 200 tornadoes across Northern Mississippi, Central and Northern Alabama, Eastern Tennessee, Southwestern Virginia and Northern Georgia resulted in 316 deaths. 15 of the tornadoes measured 4-5 on the E-F Scale, with 8 of them traveling for more than 50 miles. In Alabama, there were more than 2000 more injuries, with property damage in excess of 4.2billion dollars.

Tuesday, April 29, 2014, Mississippi, USA:
On this day, a massive Tornado ripped through Townships in Arkansas and Mississippi killing at least 34 people. It also caused various degrees of injuries to 200 more people. Homes were flattened and trees and cars were flying around. The tornado measured F3 on the Enhanced Fujita Scale. More than 2,000 homes and 100 commercial properties were reported to be damaged.

Monday, November 18, 2013, Illinois, Indiana and Kentucky, USA:
Powerful tornadoes, numbering about 30 swept through the US Midwest, killing about 8 and injuring many more. Many people were trapped in buildings. Winds up to about 68mph, carrying rain and hailstones as big as tennis balls caused massive damage to buildings and property. Entire communities were wiped away leaving nothing left.


It is known that tornadoes cause a yearly average of 400 million dollars in losses to the USA, putting tornadoes at par with hurricanes, according to a report by Lloyds in London. In 2011, about 1600 tornadoes hit the USA, causing more than 25 billion dollars in damages.  


Before, during and after a Tornado?

Before a tornado:
Sometimes tornadoes do not give weather readers much time to get people prepared to take cover. Here are a few things to do in preparation, especially if you live in a tornado-prone area:
Always be aware of the safer places  you can go to in your home before a tornado visits. If there is no basement in your home, consider finding a safe place close enough to your home where you can quickly take shelter. Make sure there are signs on the walls showing where the closest safe area is.
If there is enough time, grab a few first aid items and stock up on water and some emergency supplies, that can take you a few days if things get very bad.
Try to keep in touch with your local weather station, and look out for dark clouds and thunderstorms.
Be aware of the weather in your town and the suggested actions you can do to keep safe.

During a tornado:
During an approaching tornado, quickly move to your basement or designated area if you are in a public place. These days, schools, hospitals and many business building have safer places where people can take shelter.
If you are driving, or in a vehicle, make your way to the closest sturdy building and take cover. If there is none around, stay in your car, wear your seat belt and cover your head with your arms or a pillow if there is one. Never try to look into the window, or get out, as there may be flying debris that can smash your windows. Flying objects cause most of the injuries and deaths during tornadoes.

After a tornado:
Lots of injuries occur after tornadoes too. Be careful when getting out of your shelter as damaged objects and structures may fall.
Wear safety garments when walking and working through debris, as there could be broken glasses, exposed nails and other dangerous chemicals.
Do not touch power lines and objects in water puddles as there may be live electrical wires around.
If you have to clean up your home, make sure that you are wearing safety gear and are well aware of the dangers.
Keep records, notes, photos of broken items, in case your insurance company needs them.  


Tornado refuge area (shelter)

The destruction of structures and threat to life during tornadoes is usually caused by a combination of three factors: Wind-induced forces, Changes in atmospheric pressure and debris (airborne) impact.
There has been enough study on the factors above and there are effective engineering and architectural considerations that can make a building safe during a tornado.

Buildings with heavy masonry and concrete materials that are well tied to other parts of the structure tend to withstand extreme winds. The weight and strength of the walls are able to stop flying debris that often cause damage to property. They also resist the uplift and lateral loads caused by excessive winds, making the building a better refuge area.

Airborne debris move in all directions and refuge areas must have the capacity to shield people from the threat of flying debris. This is why basements are the best places to seek refuge during tornadoes. For building without basements, the lowest roof, first floor, interior or most enclosed places are safer.

Usually, building inspectors can assist you to locate, improve and utilize the best available refuge area, in older and more vulnerable buildings. Long roof spans and large volume open areas such as gymnasiums, auditoriums and cafeterias must be avoided. Also, areas with large expanses of glass and skylights must be avoided.
Make sure you know this preparation tip before a tornado visits. It is a good idea to put “Refuge Area” signs in school or public buildings, because many times, there is very little lead time (The current average lead-time for tornado warnings is 13 minutes) to take refuge.  




Iteresting tornado tips

Tornado Alley
There are some places in the USA, such as Oklahoma, Northern Texas, Nebraska, Kansas and Eastern Colorado, that has more tornado visits that other parts of the USA. The nickname for this belt is called Tornado Alley. (The red area on the map of USA below)


Tornado watch, prediction and warning
Unlike tropical storms or hurricanes, tornadoes cannot be predicted with precision. Is also forms at a relatively short period of time. Therefore, weather experts use strong thunderstorm activity to predict the possibility of tornadoes. Once it is formed, one can see it approaching, but by that time, it is a maximum of 13 minutes away.
A tornado watch means there a possibility of tornado, therefore, stay alert. A tornado warning means the tornado has been sighted by the radar, therefore, make your way to the refuge area.

Tornado vortex
A vortex is simply the tip that is created by spinning water or wind. If you fill the kitchen sink with water and open the drain, you notice that water rushed down, a phenomenon caused by downdraft. As water goes down, it starts to spin and then it spins faster and faster. This is similar to the vortices (more than one vortex) that occur with tornadoes. As the winds over the land surface rotates, an updraft can send the spinning winds vertical, causing a vortex. Note that there can be more than one vortex reaching downwards from thunderstorm clouds.

Tornado chasers
People chase tornadoes and storms for reasons such as research purposes and fun. Whiles this is a very dangerous move, it is important that you take extra precaution and safety measures before you engage in this. The force of nature can be catastrophic and people must not joke with it. Stay away if you are not trained to do so.