Currents and Climates

1. Current- large stream of moving water that flows through the oceans. (A river moving through the ocean).

I. Surface Currents1. driven by winds2. they move in circular patterns3. at the surface of the ocean4. 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 Stream1. 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 #1It 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 #2Waves 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 Climate1. 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 NIÑO1. 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 currents1. move and mix water around the world. 2. carry cold water from poles to equator.3. move slowly4. 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