Atmosphere and its layers -   We live on earth and there is air around us, and this blanket of air around us is known as atmosphere, Atmosphere is extended upto 800 kms from the surface of the earth. The air near the earth surface is denser and as we go higher and higher, its density decreases and it become thinner and thinner. Atmosphere mainly have five layers. 

1. Troposphere  -  This layer is extended upto 8 to 14 kms from the surface of the earth. This layer act as a medium for growth for plants and animals, all living things live on this layer, all plants grow on this layer, This layer become turbulent due to different temperature changes, all the season changes in this layer. 

2. Stratosphere - This layer extended upto 50 kms from the surface of the earth. It provide good atmosphere for aeroplanes and helicoptors. Ozone layer is also present in this layer, this ozone layer protects us from harmful UV radiations coming from the sun, if this radiation reaches on earth, the people will suffer from skin cancer. 

3. Mesosphere  -- This layer extended upto 85 kms from the surface of the earth. In this layer all the heavenly bodies like stars, comets are present, very big rocks which are known as meteoroid are present in this layer, When this big burning rocks also knows as shooting stars enter in this layer, there layers reduces them in their size. 

4. Ionosphere  - This layer is also known as thermosphere, and is extended upto 640 kms from the surface of the earth, so, just because of excessive heat in it,  as the sun heat this layer upto 1500 degree celcius, This layer also having atoms and molecules, due to heat of sun, these atoms and molecules get ionized and releases ions. 

5. Exosphere -  This layer is extended upto 800 kms from the surface of the earth. This layer is external layer