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The
dynamic stages of the water cycle are:
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Energy
from the sun evaporates water from the surfaces of masses
of water, such as oceans and lakes. This is collected
in the atmosphere. The energy enables the water to evaporate
from the surface of the earth.
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This,
together with water vapour returned to the air during
respiration, and from plants
transpiration, are taken up by warm air in the atmospheric
cycle. This evaporated water rises and condenses into
clouds.
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As
clouds rise they cool down and are unable to contain the
water vapour. This is then deposited as rain, hail, fog
and snow.
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Gravity
moves water from upland areas across the earth and back
to sea. Some water penetrates the soil called infiltration,
where it may be taken up by plants. Some water sinks through
porous rock becoming part of the groundwater mass.
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Other
water flows into lakes and rivers and returns to the seas
carrying sediments from plants and animals as well as
from the geological cycle.
Human
activity traps and uses a quantity of available water. In
Northern and Western developed countries water is often treated
as a free resource.
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