Composition of the Atmosphere :

           The atmosphere is a thick gaseous envelope which surrounds the Earth from all sides upto approximately 10000 km above the sea level. But 97% of the effective atmosphere is upto the height of 29 km. The atmosphere is composed of (i) Gases, (ii) Water vapour, (iii) Particulate matters.

(i) Gases : 

       The main components of the total gaseous composition of the atmosphere are  Nitrogen (78%) and oxygen (21%). The remaining 1% is represented by argan (0.93%), Carbon dioxide (0.03%), neon (0.0018 %), helium (0.0005%), ozone (0.00006%), hydrogen (0.00005%), Krypton, xenon, methane etc.

(ii) Water Vapour :

               Water vapour is an important gas in the atmosphere which decreases with altitude. It also decreases from the poles towards equator. In the warm and wet tropical region it contains 4% of the air by volume, but in dessert and polar region it contains less than 1%.

           More than 90% of the total atmospheric vapour is found within 5km from sea level. Water vapour in the air create several forms like fog, cloud, dew, rainfall, hail etc.

(iii) Particulate Matters: 

                     These include dust particles, salt particles, pollen,  smoke, volcanic smoke ashes etc. Most of these particles are kept in suspension in the atmosphere. These particulates helps in the scattering of solar radiation which adds varied charming colour of red and orange at Sunshine and sunset.