1. The Movement of Ocean
Water

2. Currents
Section 1

3. Currents
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A current is a large stream of
moving water that flows
through the oceans.
Currents carry water great
distances and some currents
move water at the surface of
the ocean, while others move
the deep water.
Currents move the Sun’s energy
from the equator to the poles.
They also move cold water
from the poles towards the
equator.
This moderates the climate of
our planet.

4. One Way to Explore
Currents
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Norwegian explorer
Thor Heyerdahl
proved his theory that
ocean currents
influenced human
migration by using a
raft that was powered
only by wind and
ocean currents.
He showed that
Polynesia could have
been settled from
people migrating from
South America.

5. Surface Currents
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The wind mainly drives
surface currents, which
affects water to the
depth of several
hundred meters.
If Earth were not
rotating, winds and
currents would only flow
in straight lines to the
north and south poles.
The Coriolis effect
causes the winds to
curve.

6. Coriolis Effect
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The Earth’s
rotation causes the
winds and currents
to curve in relation
to Earth’s surface.
In the northern
hemisphere the
Coriolis effect
causes the currents
to curve to the
right (clockwise).

7. Continental Deflections
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When surface
currents meet
continents, the
currents deflect,
or change
direction

8. The Gulf Stream
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The largest and most
powerful surface current
is the Gulf Stream in the
North Atlantic Ocean.
It is caused by strong
winds from the west.
The Gulf Stream carries
warm water from the Gulf
of Mexico to the
Caribbean Sea, then
northward along the coast
of the United States.
This current keeps
Northern Europe much
warmer in the winter than
it would otherwise be.

9. Ocean Current Map

10. How Surface Currents Affect
Climate
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Climate is a pattern of
temperature and
precipitation, typical
for an area over a
long period of time.
Currents affect the
climate by moving
cold and warm water
around the globe.
A surface current
warms or cools the air
above it, affecting the
climate of the land
near the coast.

11. Deep Currents
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Streamlike movements
of ocean water located
far below the surface
are called deep
currents. Deep
currents are not
controlled by wind.
Deep currents form in
parts of the ocean
where water density
increases. The density
of the ocean is affected
by temperature and
salinity.
Deep currents are
caused by changes in
density.

12. How do temperature and salinity
affect the density of the ocean??

13. Deep Currents, continued
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Formation and Movement of Deep
Currents Differences in water density
cause variations in the movement of deep
currents.

14. Currents and Climate
Section 2

15. Surface Currents and Climate
•
Warm-Water Currents and Climate
Warm-water currents create warmer climates
in coastal areas that would otherwise be much
cooler.

16. Surface Currents and Climate,
continued
•
Cold-Water Currents and Climate
Cold-water currents keep climates along a
coast cooler than the inland climate yearround.

17. Surface Currents and Climate,
continued
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Upwelling is the
movement of deep, cold,
and nutrient-rich water
to the surface of the
ocean.
The nutrients that are
brought to the surface
support the growth of
plankton. Plankton
support larger
organisms, such as fish
and seabirds.
Upwelling is shown on
the next slide.

19. El Nino
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El Nino is an abnormal
climate event that
occurs every two to
seven years in the
Pacific Ocean.
It begins when an
unusual pattern of
winds form over the
western Pacific.
This causes fast
sheets of warm water
to move eastward to
the south American
coast.
It can last one to two
years.

20. Surface Currents and Climate,
continued
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El Niño is a change in the
water temperature in the
Pacific Ocean that produces
a warm current.
Effects of El Niño El
Niño alters weather patterns
enough to cause disasters,
including flash floods,
mudslides, and droughts. El
Niño also prevents upwelling
off the coast of South
America.

21. El Nino Impact (Western Coast of
South America)
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El Nino can have
disastrous
consequences.
Warm surface water
prevents upwelling off
of the western coast
of South America.
Without nutrients
brought up by
upwelling, fish die or
go somewhere else to
find food.
Sea birds have no fish
to eat, and also must
leave the area or die.

22. El Nino (On Land)
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El Nino causes shifts in weather patterns around the world,
bringing severe conditions to different areas.
El Nino caused an unusually warm winter in northeastern U.S.
It also brought heavy rains, flooding, and mud slides in
California.
It also brought a string of deadly tornadoes in Florida.

23. Surface Currents and Climate,
continued
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Studying and Predicting
El Niño Learning as much as
possible about El Niño is
important because of its
effects on organisms and land.
To study El Niño, scientist use
a network of buoys located
along the equator. The buoys
collect data about surface
temperature, air temperature,
currents, and wind.

24. Forecasting El Nino
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Scientist don’t fully
understand the
conditions that create
El Nino
They can predict its
occurrence by using
computer models of
the world climate
Knowing when El Nino
will strike, officials will
give notice and can
plan for unusual
weather patterns.

25. El Nino (2006 hurricane season)
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Why weren’t there many
hurricanes in the 2006
hurricane season?
The seasonal activity was lower
than expected because of the
rapid development of El Nino.
This year there were only 9
named storms, 5 became
hurricanes, and 2 became
major hurricanes in Category 3
or higher.
2005 was the most active
season on record, with 28
named storms, of which 15
became hurricanes.
Five of the seven major storms
hit the US, including Katrina.