The atmosphere is an integral part of the earth. It surrounds the earth from all sides. It can be divided into five layers according to the diversity of temperature and density these are:

1. Troposphere.

2. Stratosphere.

3. Mesosphere.

4. Ionosphere.

5. Exosphere.

Troposphere: It is the lowest layer of the atmosphere. Its thickness is 8 km on the poles and 18 km on the equator. The temperature decreases in the troposphere with the increase in height at an average rate of 1°C per 165 metres. All forms of life exist in this layer. All the weather phenomena take place in this layer.

Stratosphere: It is beyond the troposphere. Ozone is present in the upper portion of the troposphere. This layer presents the ideal condition for the air flights. Ozone present in this layer prevents the ultra violet rays of the sun.

Mesosphere: Mesosphere is the third layer of the atmosphere. It is above the stratosphere. It extends up to an average height of 80 km from the mean sea level. Temperature decreases again and reaches up to 100°C at the height of 80 km. Meteors or falling stars occur in this layer.

Ionosphere: This is the fourth layer of the atmosphere. It is located above the mesosphere. It contains electrically charged ions that reflect the radio waves back to the earth, thus wireless communication and radio broadcasting process has become possible.

Exosphere: This is the uppermost layer of the atmosphere. The exact height of this layer is uncertain. It is a transition zone between the atmosphere and space. The density of this layer is very low.