The Water Cycle
The earth has a limited amount of water.
That water keeps going around and around and around and around and (well, you get the idea) in what we call the "Water Cycle".
This cycle is made up of a few main parts:
1. evaporation (and transpiration)
2. condensation
3. precipitation
Evaporation is when the sun heats up water in rivers or lakes or the ocean and turns it into vapor or steam. The water vapor or steam leaves the river, lake or ocean and goes into the air.
Condensation:
Water vapor in the air gets cold and changes back into liquid, forming clouds. This is called condensation.
Precipitation occurs when so much water has condensed that the air cannot hold it anymore. The clouds get heavy and water falls back to the earth in the form of rain, hail, sleet or snow.