The atmosphere is divided into five layers starting from the Earth’s surface

1. Troposphere — Its average height is 13 km. The air we breathe exists here. Almost all the weather phenomena like rainfall, fog and hailstorm occur in this layer. 

2. 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, making conditions most ideal for flying aeroplanes. It contains a layer of ozone gas. 

3. Mesosphere — It lies above the stratosphere. It extends up to the height of 80 km. Meteorites bum up in this layer on entering from the space. 

4. Thermosphere — In thermosphere, temperature rises very rapidly with increasing height. Ionosphere is a part of this layer. It extends between 80-400 km. This layer helps in radio transmission. In fact, radio waves transmitted from the Earth are reflected back to the Earth by this layer. 

5. Exosphere — This upper most layer. This layer has very thin air. Light gases like helium and hydrogen float into the space from here.