The word ‘atmosphere’ means a gaseous cover enveloping a planet. Without atmosphere life would not have been possible on the Earth: One-fifth of the atmosphere is oxygen and four-fifths is nitrogen. Like the Earth’s interior, the atmosphere too is made up of several layers. All animals and plants live in the lowermost layer of the atmosphere called the ‘troposphere’. All weather phenomena take place in the troposphere. Even aeroplanes fly in the outer edge of the troposphere. The stratosphere, the mesosphere, the ionosphere, and the exosphere lie above the troposphere.
