Composition of Atmosphere
The atmosphere is made up of different types of gases, water vapour and dust particles.
The composition of the atmosphere is not static.
It changes according to the time and place.
[A] Gases of the atmosphere—–
The atmosphere is the mixture of different types of gases, including water vapour and dust particles.
Nitrogen and Oxygen are the two main gases of the atmosphere. 99 percent part of it is made up of these two gases.
Other gases like organ, carbon dioxide, hydrogen, nion, helium etc. form the remaining part of atmosphere.
Ozone Gas –
The amount of ozone gas in the atmosphere is very little.
It is limited to the ozone layer but it is very important.
It protects the living beings by absorbing the ultraviolet rays of the sun.
If there was no ozone gas in the atmosphere, there would not have been existence of living beings and plants on the earth surface.
[B] Water vapour—–
Gaseous form of water present in the atmosphere is called water vapour.
Water vapour present in the atmosphere has made life possible on the earth.
Water vapour is the source of all kinds of precipitation.
Its maximum amount in the atmosphere could be up to 4 percent.
Maximum amount of water vapour is found in hot-wet regions and its least amount is found in the dry regions.
Generally, the amount of water vapour goes on decreasing from low latitudes to high latitudes.
In the same way, its amount goes on decreasing with increasing altitude.
Water vapour reaches in the atmosphere through evaporation and transpiration.
Evaporation takes place in the oceans, seas, rivers, ponds and lakes while transpiration takes place from the plants, trees and living beings.
[C] Dust Particles—–
Dust particles are generally found in the lower layers of the atmosphere.
These particles are found in the form of sand, smoke and oceanic salt.
These dust particles help in the condensation of water vapour.
During condensation water vapour gets condensed in the form of droplets around these dust particles.
Due to this process the clouds are formed and precipitation is made possible.
Importance of the Atmosphere –
 Oxygen is very important for the living beings.
 Carbon dioxide is very useful for the plants.
 Dust particles present in the atmosphere create suitable conditions for the precipitation.
 The amount of water vapour in the atmosphere goes on changing and directly affects the plants and living beings.
 Ozone protects all kinds of life on the earth from the harmful ultra violet rays of the sun.