The water cycle is the continuous movement of water on, above, and below the Earth's surface, crucial for sustaining life. It involves processes such as evaporation, condensation, precipitation, surface runoff, percolation, and transpiration, which help purify and recycle water. This complex system not only provides drinking water and food but also influences weather patterns essential for agriculture.

1. THE WATER CYCLE
THE WATER CYCLE
© Copyright 2007. M. J. Krech.
 The water cycle is the continuous
The water cycle is the continuous
movement of water on, above, and below
movement of water on, above, and below
the surface of the Earth
the surface of the Earth

3. The Water Cycle
The Water Cycle
W
Water is constantly
ater is constantly
being cycled between
being cycled between
the atmosphere, the
the atmosphere, the
ocean and land. This
ocean and land. This
cycling is a very
cycling is a very
important process that
important process that
helps sustain life on
helps sustain life on
Earth.
Earth.
Each part of
the cycle
drives the
other parts.

4. Evaporation
Evaporation
Evaporation is
Evaporation is
the process
the process
where a liquid,
where a liquid,
in this case
in this case
water, changes
water, changes
from its liquid
from its liquid
state to a
state to a
gaseous state.
gaseous state.

5. Evaporation
Evaporation
Some of the
Some of the
water in the
water in the
oceans and
oceans and
freshwater
freshwater
bodies, such
bodies, such
as lakes and
as lakes and
rivers, is
rivers, is
warmed by
warmed by
the sun and
the sun and
evaporates.
evaporates.

6. Evaporation
Evaporation
During the process
During the process
of evaporation,
of evaporation,
impurities in the
impurities in the
water are left
water are left
behind. As a result,
behind. As a result,
the water that goes
the water that goes
into the
into the
atmosphere is
atmosphere is
cleaner than it was
cleaner than it was
on Earth.
on Earth.

7. Condensation
Condensation
Condensation
Condensation
is the
is the
opposite of
opposite of
evaporation.
evaporation.
Condensation
Condensation
occurs when a
occurs when a
gas is
gas is
changed into
changed into
a liquid.
a liquid.

8. Condensation
Condensation
When the water
When the water
droplets formed
droplets formed
from
from
condensation are
condensation are
very small, they
very small, they
remain
remain
suspended in the
suspended in the
atmosphere.
atmosphere.

9. Condensation
Condensation
These
These
millions of
millions of
droplets of
droplets of
suspended
suspended
water form
water form
clouds in
clouds in
the sky or
the sky or
fog at
fog at
ground
ground
level.
level.

10. Precipitation
Precipitation
When the
When the
temperature and
temperature and
atmospheric
atmospheric
pressure are right,
pressure are right,
the small droplets
the small droplets
of water in clouds
of water in clouds
form larger
form larger
droplets and
droplets and
precipitation
precipitation
occurs. The
occurs. The
raindrops fall to
raindrops fall to
Earth.
Earth.

11. Surface Runoff
Surface Runoff
Much of the
Much of the
water that
water that
returns to Earth
returns to Earth
as precipitation
as precipitation
runs off the
runs off the
surface of the
surface of the
land, and flows
land, and flows
downhill into
downhill into
streams, rivers,
streams, rivers,
ponds and lakes.
ponds and lakes.

12. Surface Runoff
Surface Runoff
Small
Small
streams flow
streams flow
into larger
into larger
streams,
streams,
then into
then into
rivers, and
rivers, and
eventually
eventually
the water
the water
flows into
flows into
the ocean.
the ocean.

13. Surface Runoff
Surface Runoff
Surface runoff is
Surface runoff is
an important part
an important part
of the water cycle
of the water cycle
because, through
because, through
surface runoff,
surface runoff,
much of the water
much of the water
returns again to
returns again to
the oceans, where
the oceans, where
a great deal of
a great deal of
evaporation
evaporation
occurs.
occurs.

14. Percolation is an
Percolation is an
important process
important process
where rain water
where rain water
soaks into
soaks into
(infiltrates) the
(infiltrates) the
ground, into the
ground, into the
soil and underlying
soil and underlying
rock layers.
rock layers.
Percolation
Percolation (Infiltration)
(Infiltration)

15. Some of this
Some of this
water
water
ultimately
ultimately
returns to
returns to
the surface
the surface
at springs or
at springs or
in low spots
in low spots
downhill.
downhill.
Percolation
Percolation (Infiltration)
(Infiltration)

16. Percolation (Infiltration)
Percolation (Infiltration)
& Surface Runoff
& Surface Runoff

17. Percolation
Percolation (Infiltration)
(Infiltration)
Some of the water
Some of the water
percolates
percolates
underground
underground
and is called
and is called
groundwater
groundwater.
.

18. Groundwater
Groundwater
As the water
As the water
moves through
moves through
the soil and
the soil and
rock layers,
rock layers,
many of the
many of the
impurities in
impurities in
the water are
the water are
filtered out.
filtered out.
This filtering
This filtering
process helps
process helps
clean the water.
clean the water.

19. Groundwater
Groundwater
Water moves
Water moves
into caves
into caves
formed by
formed by
carbonation,
carbonation,
forming many
forming many
other
other Karst
Karst
features.
features.

20. Transpiration
Transpiration
One final
One final
process is
process is
important in the
important in the
water cycle. As
water cycle. As
plants absorb
plants absorb
water from the
water from the
soil, the water
soil, the water
moves from the
moves from the
roots through
roots through
the stems to the
the stems to the
leaves.
leaves.

21. Transpiration
Transpiration
Once the water
Once the water
reaches the
reaches the
leaves, some of
leaves, some of
it evaporates
it evaporates
from the leaves,
from the leaves,
adding to the
adding to the
amount of
amount of
water vapor in
water vapor in
the air.
the air.

22. Transpiration
Transpiration
This process of
This process of
evaporation
evaporation
through plant
through plant
leaves is called
leaves is called
transpiration
transpiration. In
. In
large forests, an
large forests, an
enormous amount
enormous amount
of water will
of water will
transpire through
transpire through
leaves.
leaves.

23. Evaporation
Evaporation
And we’re back
And we’re back
to
to Evaporation
Evaporation
again! The
again! The
endless cycle of
endless cycle of
water moving
water moving
through our
through our
planet goes on
planet goes on
and on and
and on and
on…
on…

24. The Water Cycle
The Water Cycle
 Condensation
Condensation
transpiration,
transpiration,
precipitation and all
precipitation and all
the others
the others are part of
are part of
the water cycle
the water cycle,
,
a complex process
a complex process
that not only gives
that not only gives
us water to drink
us water to drink
and food to eat, but
and food to eat, but
also the weather
also the weather
patterns that help
patterns that help
grow our crops.
grow our crops.

25. WATER
WATER Water is an
Water is an
integral
integral part of
part of
life on this planet.
life on this planet.

26. THE END
THE END
1. Why is clean water
important to you?
2. How does the water
cycle contribute to
clean water?