Currents and Climates
1. Current- large stream of moving water that
flows through the oceans. (A river moving
through the ocean).
I. Surface Currents
1. driven by winds
2. they move in circular patterns
3. at the surface of the ocean
4. They can be warm or cold.
Teach Time
• Teach your neighbor:
What is a current?
What is a surface current?
A. Coriolis Effect
A. 1. The effect of Earth’s rotation on the direction
of winds and currents.
2. If Earth were standing still, winds and currents wld
flow in straight lines btwn poles and the equator.
3. However, Earth rotates and the paths of the winds
and currents curve.
4. Northern Hemisphere- currents turn to the right.
5. Southern Hemisphere- currents turn to the left
• Teach your neighbor about the coriolis effect.
Include why the currents turn clockwise and
counterclockwise.
B. Gulf Stream
1. The largest and most powerful surface current in North
Atlantic Ocean.
2. It is caused by strong winds from the west.
3. Carries warm water from the Gulf of Mexico to Caribbean
Sea, then northward along the coast of the U.S.
4. Near Cape Hatteras, North Carolina, it curves eastward
across Atlantic, as a result of the Coriolis Effect.
• c.o.o.l. fact #1
It all started with the mail. Benjamin Franklin, a
great scientist, inventor and founding father of
the USA, was appointed joint Postmaster General
by the English King for the North American
colonies on August 10, 1753. He noticed that
ships traveling from England to the colonies
would take a week longer than those traveling
the opposite course. He asked whalers about
their experience and, in this way, learned there
was a river in the sea, called the Gulf Stream, that
flowed up the east coast of America and then
east to England, helping those ships traveling to
England, and slowing down those traveling to the
colonies.
• c.o.o.l. fact #2
Waves are most often caused by winds. But
what causes the wind? The sun. Where the
sun beats down directly on the equatorial
ocean, the ocean water and atmosphere is
hotter than at higher latitudes (north and
south). The resulting temperature imbalance
creates a poleward flow of heat that is
redistributed by atmospheric winds moving
heat away from the equator.
• (cool facts taken from the c.o.o.l. web site)
C. Effects on Climate
1. Climate- pattern of temperature and
precipitation typical of an area over a long
period of time.
2. Currents affect climate by moving cold and
warm currents around the globe.
3. Currents carry warm water from tropics
toward poles and bring cold water back
toward equator.
4. A surface current warms or cools the air above it,
influencing the climate of the land near the coast.
5. Warm moist air brings warm, rainy weather.
6. Cold water currents cool the air above them.
7. Cool air holds less water than warm air so it
brings cool, dry weather to the land in their path.
8. Ex: the Gulf Stream brings warm, moist water
from the equator to the poles. This will make
countries near the poles warmer than you would
expect them to be.
• Teach your neighbor why Europe is warmer
and wetter than it should be. Be specific.
D. EL NIÑO
1. Abnormal climate event that occurs every two
to seven years in the Pacific Ocean.
2. Begins when an unusual pattern of winds forms
over the western Pacific.
3. This causes a vast sheet of warm water to move
eastward toward South American coast.
4. Can cause flooding, heavy rains, mudslides, and
tornadoes around the world.
5. Can last one to two years before usual winds
and currents return.
II. Deep Currents
1. Causes chilly waters to creep slowly across
the ocean floor.
2. Caused by differences in density of ocean
water.
3. Density of water depends on temp. and
salinity.
1. Warm surface current moves from equator to
poles and cools.
2. As ice forms near poles, salinity of water
increases.
3. Water then becomes denser and sinks.
4. Cold water flows back along ocean floor as
deep current.
5. Deep currents move and mix water around
the world.
6. They carry cold water from the poles to the
equator.
A. Deep currents
1. move and mix water around the world.
2. carry cold water from poles to equator.
3. move slowly
4. take as long as 1000 yrs. to flow from pole
to equator and back again.
Teach your neighbor about the difference
between surface currents and deep currents.
Include: 1. temp of each (warm or cold)
2. location of each (which zone)
3. how they move (pole to equator or
equator to pole)
III. Upwelling
1. Surface currents do not usually mix with deep
currents.
2. Upwelling- movement of cold water upward
from the deep ocean.
3. As wind blows away the warm surface water,
cold water rises to replace it.
4. It brings up tiny ocean organisms, minerals, and
other nutrients from deeper layers of the water.
5. Because the nutrients are so plentiful there, it is
home to huge schools of fish. (P. 385 figure 24)
• www.brainpop.com currents