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An atmosphere is a combination of gases that surrounds a celestial body. This layer of vapors is kept together by the body’s gravity. As far as we know the earth is the only planet that has an atmosphere that can support life. Furthermore the atmosphere also acts as a shield protecting the earth from solar radiation. Understanding the earth’s atmosphere composition is vital in order to preserve the conditions needed for the birth and development of all type of life forms. The earth’s atmosphere stretches over three hundred miles and it is divided in five layers. The troposphere, the stratosphere and the mesosphere are the first three layers. The thermosphere and the exosphere are the farthest away from the earth and they merge the atmosphere with the outer space.

The troposphere is the layer closest to earth. It contains half of the earth’s atmosphere and it is composed mainly out of nitrogen and oxygen ( other gases such as argon, carbon dioxide and water vapors are present too but in very small amounts). Both nitrogen and oxygen are necessary for the development of life. The nitrogen is fixed in the earths surface and it provides nutrients for the plants while the oxygen is essential for the respiration process. The stratosphere is the next layer. Its composition is similar to the troposphere. The only difference is that the stratosphere contains a valuable component. Most of the earth’s ozone composition is found here creating the ozone layer. This thin blanket of ozone is what protects us from the sun’s heat and radiations. The mesosphere is the third layer and it is also a valuable shield. It is in this particular layer that meteors burn and disintegrate. It is composed of oxygen, nitrogen and carbon dioxide. It is also knows as the coldest layer. The thermosphere is the layer where the Aurora Borealis is formed. Its composition is also abundant in oxygen and nitrogen. Other gasses such as atomic oxygen, helium and hydrogen are present in the thermosphere’s composition but in smaller amounts. Last but not least the exosphere is a very thin layer composed of scattered particles of helium and hydrogen. It also acts as a border between the atmosphere and the outer space.

All of the atmosphere layers act as shields that protect us and ensure the necessary conditions in order for life forms to prosper. Nitrogen has the highest percentage in the earth’s atmosphere composition (78,084 %). Oxygen is the second most abundant gas (20,94 %). While these two gases are vital for sustaining life the atmosphere is composed of other elements as well such as carbon dioxide, neon,argon, helium, methane, krypton, nitrous oxide and hydrogen.

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