What is a Water Cycle?
The circulation of water between ocean and land is known as the Water Cycle.
Evaporation:
It is the process of conversion of water into water vapours by heating.
Disappearing tricks of Water:
- Water if spilled somewhere evaporates after sometime.
- Water even disappears from wet clothes as they dry up.
- It disappears from rooftops and roads after it rains.
- When light from the sun falls on the river, oceans, ponds and lakes then water from these places continuously change into vapour, but the salts dissolved into it are left behind.
Loss of Water by Plants:
- Plants need water to grow.
- They store water in different parts.
- Plants use water to prepare their food and retain some in different parts.
- Remaining water is released by the plants in the air as water vapour through the process called Transpiration.
Note:
Evaporation is a very slow process but it fastens at high temperatures i.e the rate of evaporation will be faster on sunny days when water is heated as compared when the water is kept in shade.
The vapours enter the air by evaporation and transpiration.
Condensation:
It is the process of conversion of vapor into liquid water on cooling.
For Example: If we keep a glass of cold water outside , after some time , we will be able to see water droplets on the outer surface of glass. These appear because water vapours present in the air condense on coming in contact with the cold surface of glass.
Condensation plays a very important role in bringing water back to the surface of earth which was lost in the form of vapours by evaporation and transpiration.
Formation of Clouds
- Clouds are formed by the process known as Condensation.
- As we go higher from the surface of the earth, it becomes cooler.
- At sufficient height , air becomes so cool that water vapour present in it condenses to form tiny drops of water.
- These tiny drops float in the air and become clouds.
- When these droplets become heavy they fall as rain.
- It may also fall as snow or hail.
Back to the Oceans
- Water which falls on land from rains or snow goes back to the oceans.
- Snow in the mountains melts into water and flows in the forms of stream and rivers.
- Water also falls on land in the form of rains , which also flows in the form of rivers and streams.
- Rainwater also gets absorbed into the soil , this water sometimes goes back to the air through evaporation.
- Ground water is a source of water for Wells, Lakes, Handpumps and Tubewells
- Thus, we can say that, water brought to the surface of the earth in the form of rain or snow goes back to the oceans
Water from the earth goes back into the air in the form of vapour and then returns as rain and snow.
This circulation of water is known as Water Cycle.
