ICSE Class 7 Answered

Troposphere is the lowest layer in the atmosphere and extends upwards about 10kms above sea level starting from the ground. It contains 75% of all air in the atmosphere. Generally, the temperature decreases with increase in height because the atmosphere distributes itself according to gravity. In the troposphere, the temperatures decrease with altitude. This is because the gas absorbs very little of the incoming solar radiation. Moreover, the ground absorbs this radiation and then heats the tropospheric air by conduction and convection.