Transcript The Water Cycle

CN: Water Cycle
 Continuous
Process
process by
which water
moves through
the living and
nonliving parts
of the
environment.
Sun
 The
sun provides
energy to power
the water cycle
 Without it the
water cycle
would stop
Chapter 11
Section 1 The Active River
Water Cycle
Click below to watch the Visual Concept.
Visual Concept
Water on the Earth
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Chemical Formula: H2O
Almost all the water on
Earth is salt water
(97%).
The other 3% is fresh
water
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76% of thatis frozen in
the ice caps at the poles.
Much of the remaining
is groundwater.
Evaporation
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Most important process
in the water cycle
Happens when the SUN
heats up the water in
rivers, lakes, and oceans
and turns it into a gas
(vapor or steam) and it
goes into the
atmosphere.
Most of the water vapor
that evaporates into the
air comes from the
oceans. The salt does
not get enough energy to
become a gas, so it stays
behind.
So rain is always fresh
water!
Condensation
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2nd most important
process in the water
cycle
Dew is formed by
condensation of water
vapor
Takes place in the
atmosphere
The stage where gas
turns into a liquid
Clouds

Water vapor cools as
it rises in the air.
As it reaches the
dew point, the water
vapor will condense
around dust
particles and form
clouds.
Precipitation
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Condensed water
vapor that gets
heavy enough to fall
to the ground as
rain, snow, sleet, or
hail.
Most water
molecules only spend
about ten days in
the air before
falling back as
precipitation.
Surface Runoff
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Much of the
precipitation runs
off the surface and
flows downhill into
streams. These flow
into larger streams,
then rivers, and
eventually flow back
into the ocean.
Infiltration
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Infiltration is an
important process
where rain water
soaks into the
ground, through the
soil and underlying
rock layers.
Some of this water
ultimately returns to
the surface at
springs or in low
spots downhill.
Percolation
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Percolation is
when water after it
rains seeps into the
ground and is
stored there, thus
becoming ground
water
Groundwater
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Some precipitated
water that does
not flow into
rivers, lakes, etc
sinks into the
ground (permeable)
and eventually
reaches a layer it
cannot pass
through
(impermeable).
Most of the fresh
water that is not
frozen is
underground.
Groundwater
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As the water infiltrates through the soil and rock
layers, many of the impurities in the water are
filtered out. This filtering process helps clean the
water.
The amount of
groundwater stored
is dependent on
the porosity of the
rock (like pores on
your skin)
Transpiration
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As plants absorb water from the
t
soil,
the water moves from the
roots through the stems to the
leaves.
Once the water reaches the
leaves, some of it evaporates
from the leaves, adding to the
amount of water vapor in the air.
The greatest living movers of
water are plants.
Where would you have more
moisture (water vapor)….desert
or forest? Why?
Aquifer
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An underground bed
or layer of permeable
rock, sediment, or soil
that yields water.
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Confined: permeable rock
units that are usually deep
under the ground and are
under relatively
impermeable rock or clay
that limits groundwater
movement into, or out of it
Unconfined: groundwater is
in direct contact with the
atmosphere through the
open pore spaces of the
overlying soil or rock
Water Table
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the level below which
the ground is
saturated with water.
The “line” at the top
of an UNCONFINED
aquifer
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When you start
digging in a field (fairly
deep) and you start to
see water, you are at
the water table
Artesian Well
a pumpless water source
that uses pipes to allow
underground water that is
under pressure to rise to
the surface.
This type of well seems to defy gravity
because the pressure that builds up
between layers of rock gets relieved when
the water finds a path to the open air.
In addition, the water has been naturally
filtered because it passes through porous
rock as it seeps into the Earth to reach the
aquifer, which is the underground water
source. For centuries, people have drilled
artesian wells to drink filtered water that
doesn't need to be manually or
mechanically hauled up from the depths.
Conclusion: Earth’s Water Supply
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The total amount of
water on the Earth has
not changed much since
early in its history.
The same water is cycled
over and over.
The water you drink at
lunch was probably drunk
by a dinosaur millions of
years ago!
Water Distribution