The atmosphere is divided into five layers starting from the Earth's surface. These are Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere. These are discussed below
(i) Troposphere - It is the most important layer of the atmosphere. The air we breathe exists here. Its average height is 13 km.
(ii) Stratosphere - It lies above the troposphere which extends up to a height of 50 km. This layer is almost free from clouds and associated weather phenomenon, which makes ideal conditions for flying aeroplanes.
(iii) Mesosphere - It is the third layer of the atmosphere which lies above the stratosphere. It extends up to the height of 80 km. Meteorites burn up in this layer on entering from the space.
(iv) Thermosphere - In this layer, temperature rises very rapidly with increasing height. Ionosphere is a part of this layer. It extends between 80-400 km.
(v) Exosphere - It is the uppermost layer of the atmosphere. It has very thin air and light gases like helium and hydrogen float into the space from here.