Water cycle
It is circulation of water through the process of evaporation or condensation as rain or snowfall. Water cycle is like a ring. In nature, the water cycle takes place from sea to land and back to sea again.
1.    Loss of water by evaporation
    •  During the daytime, sunlight falls on the water in oceans, rivers, lakes and ponds.
    •  As a result, water from all these places continuously evaporates into vapour.
    •  However, the salts dissolved in the water are left behind.

2.    Loss of water by transpiration
    •  Plants need water to grow.
    •  A part of this water is used to make food and another is retained in different parts of the plants.
    •  Remaining part of this water is released by the plants into air, as water vapour through the process of transpiration.

3.    Formation of water by condensation
    •  Condensation plays an important role in bringing water back to the surface of the earth.
    •  As we go higher from the surface of the earth, it gets cooler. When the air moves up, it gets cooler and cooler.

    •  At sufficient heights, the air becomes so cool that the water vapour present in it condenses to form tiny drops of water called droplets.
    •  It is these tiny droplets that remain floating in air and appear to us as clouds.
    •  Many droplets of water come together to form larger sized drops of water.
    •  Some drops of water become so heavy that they begin to fall as rain. 
    Thus, water in the form of vapour goes into air by evaporation and transpiration, form clouds, and then comes back to the ground as rain, hail or snow.
    Most of the water fall on the earth as rain.