Environmental Engineering Reference
In-Depth Information
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The Water Cycle
Water power is a
renewable
source of energy. This means water
will not run out as it is used to create energy. The Sun and Earth's
oceans are part of the water cycle. In this cycle, energy from the
Sun heats the oceans and other bodies of water. Some of this water
evaporates, becoming
vapor
. Air currents carry this vapor into the
atmosphere
. High in the atmosphere, the air is cool. This cool air
turns the vapor into tiny drops of water. These drops cling to even
smaller pieces of dust, smoke, or salt in the air. The water and the
bits the drops attach to combine to form clouds. When some of
the drops are large enough, they fall to Earth as rain, snow, or ice.
The various forms of
precipitation
keep the water cycle going.
Rain falls into streams, rivers, and oceans. Some rainwater also
goes into the ground. Over time, some of this ground water also
enters bodies of water. So does ice, after it melts. The water is
then heated by the Sun, and the cycle starts all over again.
