There are many chemical compounds found in the earth's atmosphere that act as greenhouse gases. They are called so because they allow sunlight to enter the earth's atmosphere without restraint. When this light hits the earth's surface, some of it is reflected back in the space as infra red radiation or heat.
But, the green house gases act as a shield and trap this heat within the atmosphere. Ideally, it should be so that the amount of energy that enters the earth's surface should be fairly equal to the amount of energy that leaves it. This phenomenon is imperative to maintain the temperature of the earth. The gases that prevent this from happening are carbon dioxide, methane, nitrous oxide and water vapor. There are other man made gases, like the ones used for aerosols. Let's become more familiar with these greenhouse gases which deplete the ozone cover leading to the greenhouse effect.
Carbon dioxide (CO2): A carbon dioxide molecule is made of one atom of carbon and two atoms of oxygen. This property makes this molecule apt for absorbing the infra red radiation. Once this molecule absorbs this heat it starts to vibrate. As a result it activates other molecules around it to absorb the heat too. This vicious cycle of vibration and absorption traps a large amount of heat within the atmosphere to cause the temperature to rise above normal. About 96% of carbon emissions come from the fossil fuels. Three types of fossil fuels most in use are coal, natural gas and petroleum. When these are burnt they produce carbon dioxide.
Methane (CH4): Methane has more adverse effects than carbon dioxide. It stays in the atmosphere for about 15 years. The sources that produce this gas are landfills, natural gas, petroleum use, agriculture, coal mines, transport, waste water treatment and the industries.
Nitrous oxide: Nitrous oxide is known as the most effective ozone depleting gas. Primarily, this gas is emitted by same sources as that of methane but acidic acid production and nitric acid production are its other sources. This gas is also produced naturally by sources in soil and water like the microbial action in tropical forests.
Water vapor: We must not take the water vapor lightly. It is the most powerful green house gas. At night, when the sky is cloudy, the water vapor present in the atmosphere traps the heat of the earth causing the temperature to rise. A fair example of this phenomenon is a place called Salah in Algeria. They record 52 degree centigrade in the noon and the temperature drops drastically to 3.6 degrees by midnight. This clearly shows the effect of water vapor as a greenhouse gas.
The rising emissions of these gases will gradually make life impossible on the earth. Therefore, it is important to control the emission of these greenhouse gases into the atmosphere.
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