The Water Cycle
We have an almost fixed quantity of water on the Earth. It however keeps changing its state and location in a cyclic pattern.
The cyclic pattern in which water keeps moving from oceans and seas to the sky as water vapour, from the sky to the land as rain or snow, and from land to the oceans and seas as surface water is known as the water cycle. The water cycle in nature is a continuous process.
The water in the oceans gets heated because of the heat of the Sun and evaporates, i.e. changes into water vapour. The water vapour rises up with warm air. Since it is cold higher up, water vapour cools down and condenses to form tiny droplets of liquid water. A large number of such droplets hang in the air as clouds and may travel to distant areas. When the clouds cool down further, these tiny droplets form larger drops of water and fall to the ground as rain. This is called precipitation. In colder weather, the water drops may freeze and fall as hail or snow.
This rain may fall on the oceans as well as on land. The rain that falls on land drains into rivers through streams. Some of the rain water seeps down through the soil and gathers underground as groundwater. The groundwater is pumped out for irrigation, domestic and industrial use and eventually lands into the rivers-which finally take it back into the oceans.
Some rain water gets frozen on mountains during cold weather. It melts during summers and joins the rivers on their onward journey to the oceans.
This completes the water cycle. This water again evaporates and the cycle goes on repeating.