A current is a stream of moving water that flows through the ocean. Surface currents are caused mainly by winds but not daily winds. Surface currents are caused by the major wind belts. These winds blow in the same direction all the time.

Wind or water that travels toward the poles from the equator is deflected to the east, while wind or water that travels toward the equator from the poles gets bent to the west. The Coriolis effect bends the direction of surface currents to the right in the Northern Hemisphere and left in the Southern Hemisphere.

In the Southern Hemisphere the general direction is counterclockwise.

Currents Tutorial Because the Earth rotates on its axis, circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere. This deflection is called the Coriolis effect.

There are two type of Ocean Currents:

• Surface Currents–Surface Circulation.
• Deep Water Currents–Thermohaline Circulation.
• Primary Forces–start the water moving.
• The primary forces are:
• Secondary Forces–influence where the currents flow.
• Solar heating cause water to expand.

Ocean currents play an important role in regulating the climate around the world. There are two main types of ocean currents: surface currents and deep ocean currents. Surface currents are driven by global wind systems that are fueled by energy from the sun.

Ocean currents act much like a conveyor belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics. Thus, ocean currents regulate global climate, helping to counteract the uneven distribution of solar radiation reaching Earth’s surface.

Surface currents can flow for thousands of kilometers and can reach depths of hundreds of meters….Surface Currents

• global wind patterns.
• the rotation of the Earth.
• the shape of the ocean basins.

Continental Deflections When surface currents meet continents, the currents deflect, or change direction. Currents are also affected by the temperature of the water in which they form.

Causes of the Coriolis Effect The main cause of the Coriolis effect is the Earth’s rotation. As the Earth spins in a counter-clockwise direction on its axis, anything flying or flowing over a long distance above its surface is deflected.

What are the three things affected by the Coriolis effect?

• Atmospheric Circulation Patterns. Earth rotates eastward.
• Oceanic Circulation Patterns. The winds drive the oceans, so you will notice that oceanic and atmospheric circulation patterns are very similar.
• Flight Paths.

As the difference in temperature increases between the two locations the strength of the wind increases. Therefore, the regions around 30° N/S and 50°-60° N/S are also regions where the wind, in the upper atmosphere, is the strongest.

The air that rises at the equator does not flow directly to the poles. Due to the rotation of the earth, there is a build up of air at about 30° north latitude. Some of the air sinks, causing a belt of high-pressure at this latitude.

In the tropics, near the equator, warm air rises. Air that rose just north of the equator flows north. Air that rose just south of the equator flows south. When the air cools, it drops back to the ground, flows back towards the Equator, and warm again.