The atmosphere of the Earth consists of the layer of gases commonly known as the air, which provides the surrounding around the planet Earth and is having its retention by the Earth’s Gravity. The atmosphere of the Earth protects the life on the planet by the help of creation of pressure making allowance for the liquid water to exist on the Earth’s surface also absorbing ultraviolet radiation from the sun warming the surface through heat retention and reducing the extreme temperature between the intervals of day and night.

The earth’s atmosphere can be divided into five main layers, these are-

i) Exosphere- this is referred to as the outmost layer of the Earth’s atmosphere. It has the starting point from the exobase, which is situated at the top of this layer at about a distance of 700 km above the mean sea level, to about 10,000 km, at a point where it merges into the solar wind. Exosphere is mostly composed of extreme low densities of hydrogen, helium and variety of other heavier molecules such as nitrogen, oxygen and carbon dioxide. The atoms and the molecules in this layer are so far apart that the can travel up to hundreds of kilometers without even colliding with each other.

ii) Thermosphere- this is the second highest layer of the Earth’s atmosphere which extends from the mesopause which is located at an altitude of 80 km up till the thermopause which is again located at a height ranging from 500-1000 km. changes in the solar activity lead to the variation of height in this layer. Lying at the lower boundary of the exosphere, it is also referred to as the exobase.

iii) Mesosphere- this is the third highest layer of the atmosphere occupying the entire region from above the stratosphere till the below of the thermosphere. The Mesosphere extends from the stratopause from an altitude of 50km to the mesopause at 80-85 km above the mean sea level.  This is the layer where the meteors burn into ashes on entering into the earth’s atmosphere.

iv) Stratosphere- it is the second-lowest layer of the Earth’s atmosphere which lies just above the troposphere and is separated from it with the help of the tropopause. This layer has its extension from the top of the troposphere at a rough distance of 12 km above the Earth’s surface till it reaches the stratopause at a height ranging from 50-55 km. This is the layer which consists of the ozone layer, which again absorbs the harmful rays of Ultraviolet radiation from reaching the earth’s surface and harming the life on earth.  

v) Troposphere- this is the lowest layer of the Earth’s atmosphere which extends from a height of 12 km, however this altitude varies from 9 km to 17 km at the geographical poles having changes due to the weather. The troposphere is having a boundary of the tropopause, which is marked by temperature inversion and in the other regions which maintain an isothermal characteristic with the usage of height.