Question

The amount of water vapour present in the air is termed as _______ .

Answer 1

Hint: Water vapour is invisible and it is the gas state of H₂O. Water vapour serves as the raw material for cloud and rain formation.

Complete answer:
The amount of water vapour in air must be measured at weather stations and it can vary on regional scales. Using a psychrometer we can measure the actual air (dry bulb) temperature and it is called as wet-bulb temperature.
The water vapor is produced from boiling of liquid water or from evaporation or from the sublimation of ice. It is transparent in the atmosphere like most of the constituents. Water vapor is generated continuously by evaporation and removed by condensation under the typical atmospheric conditions.
The amount of water vapor present in air is called absolute humidity. In the air the amount of water vapor is compared with the amount of water that the air can hold and it is called relative humidity.

Note:
When warm air hits the cold surface, such as glass, the water vapor condenses into droplets by leaving its gaseous state. Atmosphere is made up of nitrogen and oxygen, it also has tiny amounts of argon, carbon dioxide and other gases. Water vapor is also present in it, but the amount varies as it depends on the temperature. The amount of water vapor in air ranges from 0.001 percent to about 4 percent.