Water in the Atmosphere
Air always contains water vapour, which varies from 0 to 4% by volume of the atmosphere. Water vapour present in the air is known as humidity. Humidity is expressed in three ways:
It plays an important role in the weather phenomena. The moisture in the atmosphere is present in the three forms, i.e., solid, liquid and gaseous. These three forms of atmospheric moisture forms a continuous cycle between the atmosphere, oceans and continents in the form of hydrological cycle.
The exchange of water takes place through physical processes like, evaporation, condensation and precipitation.
Process by which water is transformed from liquid to gaseous state is called evaporation.
The Physical process of transformation from the vapour to the liquid state is called condensation. Different forms of condensation are dew, frost, fog, mist and clouds.
After the condensation of water vapour, the release of moisture in the form of water droplets and ice is known as precipitation. Different forms of precipitation are snowfall, sleet, hail and rainfall.
Different types of rainfall are convectional rain, orographic rain and cyclonic rain.
Different places on the Earth’s surface receive different amounts of rainfall in a year in different seasons.
Thus, there is a never-ending interchange between the different states of water.