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Currents and Climates
How do oceans move?
Oceans move as a result of wave actions, tides, and currents.
What is a current?
A current is a large stream of moving water that flows through the oceans.
Unlike waves, which do not actually transport water from one place to another, what do currents do?
Currents carry water great distances.
How do currents move water?
Some currents move water at the surface of the ocean, while other currents move the deep water.
How do surface currents affect the water?
Surface currents affect water to a depth of several hundred meters.
How are surface currents driven?
Surface currents are mainly driven by winds.
How do surface currents move if you follow the major wind patterns of the globe?
Surface currents move in circular patters in the 5 major ocean basins.
How do surface currents flow?
Surface currents flow east or west and then double back to complete the circle.
Why do currents move in these circular patterns?
As Earth rotates the paths of the winds and currents curve in relation to Earth's surface.
What is the Coriolis Affect?
The effect of Earth's rotation on the direction of winds and currents.
How does the Coriolis effect the Northern Hemisphere?
The Coriolis effect causes the currents to curve to the right.
How does the Coriolis effect the Southern Hemisphere?
The Coriolis effect causes the currents to curve to the left.
What is the largest and most powerful current in the North Atlantic Ocean?
The Gulf Stream
What causes the Gulf Stream?
The Gulf Stream is caused by strong winds from the west.
What does the Gulf Stream resemble?
The Gulf Stream resembles a fast moving, deep blue river within the ocean.
Describe the Gulf Stream.
It is more than 300 km wide, 300 m deep, and it carries a volume of water 100 times greater than the Mississippi River.
What kind of water does the Gulf Stream carry?
Where does the Gulf Stream carry water?
The Gulf Stream travels from the Gulf of Mexico to the Caribbean Sea, then northeast along the coast of the U.S.
What happens to the Gulf Stream near Cape Hatteras, NC?
As a result of the Coriolis effect, the Gulf Stream curves eastward across the Atlantic.
What is climate?
Climate is the pattern of temperatures and precipitations typical of an area over a long period of time.
How do currents affect climate?
Currents affect climate by moving cold and warm water around the globe.
In general, how do currents carry water?
Currents carry warm water from the tropics toward the poles and bring cold water back toward the equator.
How does a surface current influence the climate?
A surface current warms or cools the air above it, influencing the climate of the land near the coast.
What happens when wind blows across warm water currents?
Winds pick up moisture.
What do cold water currents do?
Cold water currents cool the air above them.
What kind of climate does cold air bring?
Since cold air holds less moisture than warm air, these currents bring cool, dry weather.
What cause the chilly waters at the bottom of the ocean?
What causes deep currents?
Deep currents are caused by differences in density rather than surface winds.
What causes the density of the water?
The density of water depends on its temperature and salinity.
If the water is more dense, what is the salinity?
If the water is less dense, what is the salinity?
What happens when warm water surface currents move from the equator toward the poles?
It gradually cools off.
What happens to the salinity of the water as ice forms near the poles?
The salinity of the water increases from the salt left behind during freezing.
What happens as the water's temperature decreases and salinity increases?
The water becomes denser and sinks, then the cold water flows back along the ocean floor as deep current.
Are deep currents affected by the Coriolis effect?
How do the deep ocean currents flow?
Deep currents follow the hills and valleys of the ocean floor. They also carry cold water from the poles back to the equator and travel much more slowly than surface currents.
What happens when surace waters and deep ocean waters mix.
Upwelling which is the upward movement of cold water from the ocean depths.
What causes upwelling?
The winds cause upwelling when they blow away the warm surface water and cold water rises to replace it.
What does upwelling do?
Upwelling brings up tiny ocean organisms, minerals, and other nutrients from the deeper layers of the water.
What is El Nino?
EL Nino is an abnormal climate event.
When does El Nino occur?
El Nino occurs every 3 to 5 years in the Pacific Ocean.
How does El Nino occur?
El Nino begins when tropical waters in the western Pacific heat up more than usual.
What does the warmer than usual waters do?
The warmer water causes and unusual pattern of winds to form, which push warm water from the equator toward the South American coast.
How long can El Nino last?
El Nino conditions can last for one to two years before the usual winds and currents return.
What can El Nino do?
El Nino can have disastrous consequences. It prevents upwelling off the western coast of South America.
What happens if there is no upwelling?
Without the nutrients brought up by upwelling, fish die or go elsewhere to find food, ruining the fishing catch that season.
What else can happen without the upwelling?
It also causes shifts in weather patterns around the world.