From the Winter 2009 Conservationist for Kids

Earth's Water Cycle

By Gina Jack

New water can't be made. What we have is all we get. Earth's water cycles through many uses and through different forms. It may be liquid water, solid ice or water vapor in the air. It is reused over and over again. The water you drink today is the same water dinosaurs drank millions of years ago!

The image shows the Earth's water cycle

When water falls to the earth's surface (precipitation) it moves quickly along (surface runoff) and forms streams and rivers. It then flows into lakes and oceans.

Some water seeps into the ground and fills the spaces between soil particles and in porous rocks. Water in the ground (groundwater) flows slowly through the tiny spaces. After a long time, sometimes years, it reaches the surface in low-lying areas and joins streams and lakes.

Water at the surface is warmed by the sun's heat energy and evaporates into the air. Water vapor is also added from the breath of animals, including people (respiration). (When you see your breath on a cold day, you're seeing the water vapor.) Plants give off water vapor, too (transpiration). The water vapor in the air condenses and forms clouds. The cycle continues as water from the clouds once again falls to the Earth's surface.