The sphere of air that wraps the Earth from all sides is called ‘Atmosphere*. It extends up to about 1600 km from the surface of the Earth and it cannot be seen clearly with the naked eye.

Uses of atmosphere :

• Oxygen in the atmosphere is essential to all living organisms on the earth.
• Nitrogen is necessary for the growth of vegetation.
• Carbon dioxide is the food for green vegetation.
• Nitrogen reduces the intensity of oxygen.
• Ozone gas absorbs the ultra-violet sunrays and thus protects the earth from the intense heat’ of the sun. Ozone is also an invigorating gas.
• The dust particles in the atmosphere help to spread sunrays in all directions. So there is neither sudden light after sunrise nor sudden darkness after sunset. Dust particles reflect sunrays which help us to receive sunlight. These particles also help to form clouds.
• We can hear sound only due to the atmosphere. Radio broadcasts and television are possible only due to the presence of atmosphere.