HOW THE CYCLE WORKS
Of the world’s water, 97% is saltwater stored in the ocean. Nearly all the rest is on or under the land surface, and a tiny fraction exists in the atmosphere. The vast majority of water on land surfaces is in polar ice caps. Of the remaining available fresh water, approximately one-fifth is contained in the Great Lakes of North America. The water cycle, described here, is a closed loop that describes how water links major water bodies, the atmosphere and the land as it evaporates, precipitates, then flows. It is in permanent motion, constantly changing from liquid to gas to solid.