This PowerPoint file contains information about the water ...

[Pages:15]This PowerPoint file contains information about the water cycle. The first slide shows a picture that

includes all processes in the water cycle. Subsequent slides discuss each process individually. The last slide provides information on the distribution of water on the earth.

The water cycle is the continuous movement of water on, above, and below the surface of the Earth

United States Geological Survey ()

Evaporation is the process by which water changes from a liquid to a gas. The rate of evaporation

depends on how dry the air is and the temperature difference between air and water.

Water Evaporating

from hot springs

United States Geological Survey ()

Transpiration is the process by which water evaporates from plants

Evaporation and transpiration are often combined into a single

term called evapotranspiration.

United States Geological Survey ()

Condensation is the process by which water vapor in the air is changed into liquid water. As air rises it cools. Cold air holds less water than warm air. Thus, as the air cools, clouds form.

Some clouds form during the day as the air temperature and

evaporation increase. Other clouds are associated with weather systems, such as a warm or cold front, in which warm air is forced over colder air.

United States Geological Survey ()

Precipitation is water released from clouds in the form of rain, freezing rain, sleet, snow, or hail. It happens when clouds can no longer hold water. The water then falls to the earth because of gravity.

A thunderstorm in the western United

States. Thunderstorms form

when air is forced upward at a very fast

rate and therefore cools very quickly.

United States Geological Survey ()

Water infiltrates much faster and

deeper into a sand compared to a clay. This is because the pore

spaces in the sand are much larger than in the clay and can

therefore transport more

water.

Infiltration is

SAND

the process by

which water

soaks into the

ground.

Water Infiltration is faster on dry

soils and in

sandy soils

CLAY

compared to

wet and clay

soils.

Surface runoff is precipitation or melted snow that runs off over the landscape. Runoff occurs when the rate of precipitation or snowmelt is greater than the

rate of infiltration.

Runoff water flows to sewers in some urban areas (then usually to

surface water), to retention basins in other urban areas (then usually soaks into the ground), and to rivers, lakes, and wetlands in nonurban areas.

Oregon State University Extension Service

()

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