Did you know that the water we have on earth today is hundreds of years old? Basically, the same water flows repeatedly from one source to another. The cycle that is completed by this return of water is therefore the water cycle. In the heat of the sun, ponds, canals, rivers, and seawater turn into water vapor.
This water vapor rises to the top of the atmosphere, becomes cold, and turns into tiny water particles. When the water particles in the clouds become too cold, they turn into ice and fall to the earth as hail. And in this way, the same water keeps coming to the earth again and again through the water cycle.