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Different layers of the Earth's Atmosphere:

The atmosphere of Earth is a layer of air or gases surrounding it. This layer of atmosphere protects life on Earth by absorbing Ultraviolet radiations and by maintaining temperature. Air contains 79% Nitrogen, 21% Oxygen, and the remaining consists of carbon dioxide, argon and other smaller gases. Water vapour and other gases exist in small amounts as well.

The atmosphere of the Earth is divided into five layers. The list is given below, from closest to farthest from Earth -

LayerDescription
Troposphere
(0 - 12 km)
This layer of the atmosphere is closest to the earth. Weather occurs in this layer and contains half of the Earth's atmosphere. The temperature of the troposphere decreases with height. Clouds are found here due to the presence of water vapour and dust particles in the atmosphere.
Stratosphere
(12 - 50 km)
Above the Troposphere is the Stratosphere. Ozone is abundant here and it heats the atmosphere. Ozone also protects Earth by absorbing harmful radiations from the Sun. The atmospheric pressure at the top of the stratosphere is thousand times less than that at the sea level. Due to this reason aeroplanes fly here.
Mesosphere
(50 - 80 km)
Above the Stratosphere is the Mesosphere. In this layer temperature decreases with height. Mesopause, the top of the Mesosphere, is the coldest part of Earth's atmosphere. Meteors burn up in this layer.
Thermosphere
(80 - 700 km)
Temperature increases with height in this layer and can rise to as high as 3000 degree Fahrenheit. In this layer Space Shuttle and International Space Station orbits Earth. This is also the layer where the auroras occur.
Exosphere
(> 700 km)
It is the outermost layer of the Earth's atmosphere. It is composed of very widely dispersed particles of hydrogen and helium. This layer is very thin i.e. it has very few atmospheric molecules which escape into space.