What is the water cycle?
The water cycle is the continuous movement of water between the oceans, the air and the land through evaporation, condensation, precipitation and collection.
The Sun heats water in oceans, lakes and rivers, turning some of it into water vapor, a process called evaporation. Plants also release water vapor through their leaves, called transpiration. The vapor rises into the atmosphere, cools and condenses into tiny droplets that form clouds.
When droplets in clouds combine and grow heavy enough, they fall as precipitation: rain, snow, sleet or hail. On land, water runs off into rivers and lakes, soaks into the ground as groundwater or is stored as ice in glaciers. Eventually, most of it flows back to the sea, and the cycle begins again.
Where Earth's water is
About 97 percent of Earth's water is salt water in the oceans. Most fresh water is locked in ice caps and glaciers or underground. Less than 1 percent is easily available fresh water in lakes, rivers and the atmosphere, which is why protecting it is so important.
Did You Know?
A water molecule may spend thousands of years in the ocean or deep underground, but on average it stays in the atmosphere for only about nine days.