Water that falls on the continents soaks into the ground or runs off into lakes and streams. Much of the water that soaks in or runs off eventually finds its way back to the atmosphere through evaporation. Some of this water is taken up by plants, which then release it into the atmosphere in the form of water vapor through pores in their leaves. This process is called transpiration.

Water that precipitates at high elevations may become part of a snowfield or glacier. Although this water may be tied up in snow or ice for many years, it will eventually melt and continue its path to the sea.

The movement of water through the hydrologic cycle provides a renewable source of harvestable energy.