Air is called the breath of life because it contains all necessary gases that are required for the survival of life forms on this planet. It is a mixture of gases such as nitrogen, oxygen, argon and carbon dioxide. It also contains water vapour and suspended dust particles. Oxygen gas is required for respiration and burning.

Following are the functions of air or atmosphere:

(i) It helps in controlling climate by covering the Earth like a blanket and keeps the average temperature of the Earth fairly steady during the entire year.

(ii) It creates wind by moving in different directions and helps in warming and cooling the land.

(iii) The air carrying water vapour forms clouds when the water vapour condenses around a nucleus of dust and other suspended particles. The cloud formation results in subsequent rainfall.

(iv) It forms an ozone layer around the Earth and protects it from the harmful ultraviolet (UV) radiation of the sun.