Describe the composition of atmosphere.

Explanation

The atmosphere is composed of gases, I water vapour and dust particles. Nitrogen constitutes 78.8%, oxygen contributes 20.94% and argon contributes 0.93% in atmosphere. Other gases include carbon dioxide, helium, ozone, methane, hydrogen, krypton, xenon and neon, etc. Nitrogen and oxygen together constitute 99% of the atmosphere. Neon, krypton, xenon are scarce gases. The proportion of gases changes in the higher layers of the I atmosphere in such a way that oxygen will be almost in negligible quantity at the height of 120 km. Similarly, carbon dioJcide and water vapour are found only 1 up to 90 km from the surface of the earth.