The Water Cycle for Schools

Science Center Objects

Earth's water is always in movement, and the natural water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Water is always changing states between liquid, vapor, and ice, with these processes happening in the blink of an eye and over millions of years.

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Drippy - Water Science School

What is the water cycle? I can easily answer that—it is "me" all over! The water cycle describes the existence and movement of water on, in, and above the Earth. Earth's water is always in movement and is always changing states, from liquid to vapor to ice and back again.

The water cycle has been working for billions of years and all life on Earth depends on it continuing to work; the Earth would be a pretty stale place without it.



The Water Cycle for Schools and Kids


 A summary of the water cycle

You may think that every drop of rain that falls from the sky, or each glass of water that you drink, is brand new, but it has always been here and is a part of the water cycle. 

  • The heat of the sun provides energy to make the water cycle work.
  • The sun evaporates water from the oceans into water vapor.
  • This invisible vapor rises into the atmosphere, where the air is colder.
  • The colder air causes water vapor to condense into water droplets and clouds.
  • Volcanoes can produce steam, which forms clouds.
  • In the atmosphere, air currents move clouds all around the Earth.
  • Water drops form in clouds, which then fall to Earth as precipitation (rain and snow).
  • In cold climates, precipitation builds up as snow, ice, and glaciers.
  • Snow can melt, becoming runoff, which flows into rivers, the oceans, and into the ground.
  • Some ice evaporates directly into the air, skipping the melting phase (sublimation).
  • Rainfall on land flows downhill as runoff, providing water to lakes, rivers, and the oceans.
  • Some rain soaks into the ground, as infiltration, and, if deep enough, becomes groundwater.
  • Water from lakes and rivers can seep into the ground.
  • Water moves underground because of gravity and pressure.
  • Groundwater close to the land surface is taken up by plants.
  • Some groundwater seeps into rivers and lakes, and can flow to the surface as springs.
  • Plants take up groundwater and evapotranspire, or evaporate, it from their leaves.
  • Some groundwater goes very deep into the ground and stays there for a long time.
  • Groundwater flows into the oceans, keeping the water cycle going.