A1.2.1.1 Water Cycle

In simplified terms, water evaporates into the atmosphere. It condenses and then falls to the earth as precipitation. On the earth the water is collected and then evaporates back into the atmosphere.

Source: http://www.usgcrp.gov/usgcrp/images/ocp2003/ocpfy2003-fig5-1.htm


Evaporation occurs when the suns heats water (in rivers, lakes and the sea) turning it into water vapour. This water vapour then rises into the air.


Condensation occurs when the ait becomes cold and the water vapour changes back into water liquid. An obvious example of this is when water vapour touches a cold window, turning back into water and forming condensation on the window.


Precipitation is rain, hail, sleet and snow. It occurs when there is there is more condensed water in the atmosphere than the air can hold. The condensed water falls back to earth. Whether it is as rain, hail, sleet and snow depends on the temperature.