Our atmosphere is the protective covering over the earth. Although there are no perceivable layers or distinguishable boundary marks, the atmosphere can be divided into layers for the sake of comprehension. The atmosphere comprises of five layers: the troposphere, the stratosphere, the mesosphere, thermosphere and the exosphere.
Animals and plants live in the troposphere. This is because this layer is rich in oxygen, which is an indispensable element for the survival of life. The troposphere be-gins at the surface of the earth and extends to between 7 km at the poles and 17 km at the equator. The tropopause is the boundary between the troposphere and stratosphere.
The next layer is called stratosphere and it extends from the tropopause to about 51 km upwards. The stratopause, which is the boundary between the stratosphere and mesosphere, typically is at 50 to 55 km. The mesosphere extends from the stratopause to 80-85 km. It is in this layer where most meteors burn up upon entering the atmosphere.
The top of the thermosphere is the bottom of the exosphere, called the exobase. The height of exosphere varies with solar activity and ranges from about 250 to 800 km. The outermost layer of Earth’s atmosphere is called exosphere.
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