The Water Cycle

The total amount of water on Earth stays relatively constant; however, it does move about, changing phases (solid, liquid, gas) and locations. The water cycle tracks the movement of water as it progresses through the states of matter and travels through the biosphere, atmosphere and geosphere. The hydrologic cycle (another name for the water cycle) is responsible for circulating water between the Earth's reservoirs. The water cycle not only transports and recycles water, it is also critical for maintaining habitable conditions on Earth.

The water cycle includes the processes of evaporation, condensation, precipitation, transpiration, infiltration, and runoff. It also includes the collection & storage of water in earth's reservoirs.
Evaporation: water changes to water vapor
Condensation: water changes from a gas to a liquid.
Precipitation: water falls to Earth as rain, snow, sleet, hail, etc.
Transpiration: liquid water from the leaves of plants changes to water vapor
Infiltration: water that seeps into the soil and can become groundwater
Runoff: water on the surface of earth that does not infiltrate the ground

Most of the water on earth is found in its oceans, but when the surface of a body of water gets warm it vaporizes, entering the air as gas and rising to form clouds. As more and more water enters the air it precipitates and falls to earth as rain or snow. It then either returns to the oceans or sinks into the soil or flows into rivers.


Last modified: Friday, 6 January 2012, 10:03 AM