Water cycle

Science

Definition

The continuous movement of water through Earth's systems via evaporation, condensation, precipitation, and collection. Water cycles between the atmosphere, land, oceans, and living organisms, driven primarily by solar energy and gravity.

How It Works

  1. Solar energy heats surface water in oceans, lakes, and rivers, causing evaporation into water vapor.
  2. Plants release water vapor through transpiration, adding to atmospheric moisture.
  3. Warm, moist air rises, cools, and water vapor condenses around particles to form clouds.
  4. Water droplets in clouds grow and fall as precipitation (rain, snow, sleet, or hail).
  5. Precipitation either runs off the surface into streams and rivers or infiltrates into the ground as groundwater.
  6. Water collects in oceans, lakes, and aquifers, and the cycle begins again.

Examples

  • Rain falling on mountains flowing into rivers that eventually reach the ocean
  • Morning dew forming on grass as water vapor condenses on cool surfaces overnight
  • Groundwater slowly filtering through rock layers over thousands of years before emerging at a spring

Related Terms

Groundwater Biogeochemical cycles Weather patterns Erosion and deposition

Study This Concept

Practice water cycle with free review games in these units:

Earth Science Unit 5: Oceans and Water