The Water Cycle Explained
Water never leaves Earth, it just keeps moving between sea, air and land.
The water cycle describes how water moves around our planet. It has no real beginning or end, but a good place to start is with the Sun, which provides the energy that drives it.
Heat from the Sun causes water from oceans, lakes and rivers to evaporate into the air as vapour. Plants also release water vapour through their leaves, a process called transpiration. As the vapour rises it cools and condenses into tiny droplets that form clouds.
When droplets grow large enough they fall as precipitation: rain, snow, sleet or hail. Some of this water runs over the surface into streams and rivers, some soaks into the ground to become groundwater, and some is stored as snow and ice. Eventually, nearly all of it returns to the sea, and the cycle begins again.
About 97 percent of Earth's water is salty ocean water. Of the fresh water that remains, most is locked up in glaciers and ice caps, so only a small fraction is available in rivers, lakes and underground for people, animals and plants.