Sea, river, lake, canal, pond, etc. Are called water bodies. The transfer of water from water bodies to the atmosphere and its return back is called water cycle (figure 4.6). The sun shines on water bodies, makes the water evaporate into the atmosphere in the form of vapours. Evaporation also takes place from plants (transpiration) and surface of snow on the mountains. As these vapours rise up, they lose energy and condense into water droplets. At a certain height, these water droplets gather in the air and form clouds. The water droplets in the clouds get heavier and heavier and the air cannot hold them anymore.
Role of Evaporation and Condensation in the Water Cycle
The water then falls down in the form of rain and snow. The rain water again flows to the rivers, streams, lakes, canals and sea. In this way, water is always moving in a cycle. The processes of evaporation and condensation are involved in the water cycle. Water goes through its three phases (liquid, solid, gas) as it cycles in the Earth system; it evaporates from plants as well as land and water surfaces into the atmosphere and after condensing in clouds, returns to the Earth as rain and snow.