What happens if it does not rain for a long period?

4.    Water Back to Ocean :
    The water that falls on the land as rain and snow sooner or later goes back to oceans. This may happen in many ways.

Cloud formation

Cloud formation :
            •  When the air moves up, it gets cooler and cooler.
            •  At sufficient heights, the air becomes so cool that the water vapor 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.