1. Ocean Circulation
Currents and Causes

2. What is a Current?
Ocean water that moves in ‘streams’ or ‘rivers’ based on similar characteristics
Two main types
Surface
Deep-water

3. Surface Currents Caused by winds Trade winds (N/S of Equator)
Westerlies (mid latitudes)

4. Surface Currents
These currents move horizontally in the upper part of the ocean’s surface.
Develops from friction between ocean surface and wind blowing across it.

5. Surface Currents Upwelling
When warm water is ‘blown’ away and cold nutrient rich water rises to the surface
La Nina conditions - normal
El Nino is when the upwelling becomes downwelling

6. Surface Currents Gyres
Huge circular moving current systems that dominate the surfaces of the oceans.

7. Gyre:

8. Surface Currents
Coriolis Effect is the deflection away from their original course as a result of Earth’s rotation.

9. Deep-Water Currents Density Current Moves vertically
Results from density differences among the water masses

10. Deep-Water Currents Density Current
Can be caused by a decrease in temperature or an increase in salinity

11. Deep-Water Currents Density Current Cold water from the poles sinks
Can take thousands of years to make a complete cycle around the ocean floor

12. Conveyor Belt Model

13. Key Currents to Know Gulf Stream Warm Off east coast of US
California Current
Cold
Off west coast of US