Answer the following Questions Briefly:

Define atmosphere

The blanket of air that surrounds the earth is called atmosphere which is held close to the surface of the earth by gravitational force. The atmosphere of the earth protects life on earth by the harmful radiations of the sun like ultraviolet rays, greenhouse effect and also helps in reducing the temperatures extremes between day and night.

Composition: the three major constituents of the earth's atmosphere are nitrogen, oxygen, and argon. Water vapour accounts for roughly 0.25% of the atmosphere by mass.