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THE WATER CYCLE
Dec/21/2010
THE WATER CYCLE
The water cycle or hydrologic is a continuous cycle where water evaporates,
travels into the air and becomes part of a cloud, falls down to earth as
precipitation, and then evaporates again. This repeats again and again in a
never-ending cycle. Water keeps moving and changing from a solid to a liquid to
a gas, over and over again. Precipitation creates runoff that travels over the
ground surface and helps to fill lakes and rivers. It also percolates or moves
downward through openings in the soil to replenish aquifers under the ground.
Some places receive more precipitation than others do. These areas are usually
close to oceans or large bodies of water that allow more water to evaporate and
form clouds. Other areas receive less precipitation. Often these areas are far
from water or near mountains. As clouds move up and over mountains, the water
vapor condenses to form precipitation and freezes. Snow falls on the peaks.
THE OCEANS AS STOREHOUSES
The water cycle sounds like it is describing how water moves above, on, and
through the Earth ... and it does. But, in fact, much more water is "in storage"
for long periods of time than is actually moving through the cycle. The
storehouses for the vast majority of all water on Earth are the oceans. It is
estimated that of the 332,500,000 cubic miles (mi3) (1,386,000,000 cubic
kilometers (km3)) of the world's water supply, about 321,000,000 mi3
(1,338,000,000 km3) is stored in oceans. That is about 96.5 percent. It is also
estimated that the oceans supply about 90 percent of the evaporated water that
goes into the water cycle.
AN ESTIMATE OF WORLDWIDE DISTRIBUTION
Water Source Water Volume (in cubic miles) Percentage of Total Water
Oceans, Seas, and
Bays
321,000,000
96.5%
Total Global
Water
332,500,000
100.00%
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