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The Chemical Cycles

Unlike energy, matter can be recycled. The Water, Carbon, and Nitrogen Cycles are the three main ways matter is recycled in the environment.

The Water Cycle
More than ninety percent of the Earth's water is locked beneath its surface either in crystal rocks or deep in the interior and does not take part in the water cycle. A large portion of the water that does participate in the water cycle comes from the Earth's oceans.

Illustration of the Water CycleStep 1:  A large quantity of water evaporates from the surface of the ocean. Evaporation is the conversion of liquid water to a gaseous form of water called water vapor.

Step 2: The water vapor then condenses to form clouds. Most of this condensed water will then precipitate back into the ocean, but some will travel on and eventually float over land. Precipitate means to condense from a vapor and fall as rain or snow.

Step 3:  The condensed water (clouds) that floats over land picks up more water vapor from evaporation and transpiration. Transpiration is the evaporation of water from the leaves of plants.

Step 4:  The accumulated water vapor will then fall to the ground as rain.

Step 5:  The rain water makes its way back to the ocean through streams and rivers and starts the water cycle over again.

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