1. Ocean Currents

2. Bill Nye Ocean Currents Episode

3. What are Ocean Currents?
Ocean currents are the vertical or horizontal movement of both surface and deep water throughout the world’s oceans.
Currents normally move in a specific direction and aid significantly in the circulation of the Earth’s moisture, the resultant weather, and water pollution.

4. Ocean Currents There are two types of ocean currents:
Surface Currents: are wind driven and affect about 10% of the ocean water, but cover the entire ocean surface.
Thermohaline Currents: (heat/salt) = density driven currents. They occur deeper in the ocean and affect ~ 90% of the ocean water.

5. Hot/Cold Currents
Warm Currents: Gulf Stream, Alaskan, Kuroshio, Brazil, South Equatorial, North Equatorial, East Australian, North Atlantic, North Equatorial, East Australian
Cold Currents: West Wind Drift, Humboldt, California, Canary, Bengula, West Australian, Labrador, Gulf Stream

7. Surface Currents Surface currents are mostly horizontal currents.
These currents follow the pattern of the wind e.g. the Westerlies/ Trade winds
They occur from the surface down to a few hundred meters.
Generally travel clockwise in the northern hemisphere and counter clockwise in the southern hemisphere.

8. Factors that influence Surface Currents…
Uneven heating of the atmosphere
Rotation of the earth (Corolis Effect)
Continents

9. 1. Uneven Heating of Atmosphere
Cause Winds and then creates currents.
Earth’s attempt to redistribute energy equally across the world

10. 2. Rotation of the Earth Corolis Effect
Northern Hemisphere: deflects currents to the right (causes clockwise movement)
Southern Hemisphere: deflects currents to the left (causes counter-clockwise movement)

12. 3. Continents
Moving ocean currents are forced to turn when they meet a continent

13. Significance of surface currents
Surface currents cause the general “mixing” of the worlds oceans and waters
move nutrients from more productive areas to less productive areas of the oceans.
Important role in migration and the movement of many less active (or passive) organisms.

14. Deep currents
Thermohaline currents are driven by density, salinity and temperature changes in water.
These currents are also known as the “ocean’s conveyor belt”
They flow under the surface of the ocean and move significant amounts of ocean water vertically.

15. Significance of deep currents
Form upwelling: the drawing up of cold water from deeper regions to shallow waters throughout the Ocean
Result: all ocean nutrients don’t end up settling on the bottom: surface organisms can benefit from decomposers, cycle nutrients and sustain life.

16. Gyres
These currents are deflected by the continents and driven by surface winds, causing them to bend and create large current loops called circulation gyres.
The centers often collect floating mats of seaweed and garbage. (Sargasso Sea and the N. Pacific gyre garbage patch.)

18. “The Great Conveyor Belt”
A global "conveyor belt" is set in motion when cold water forms in the Northern Atlantic, sinks, moves south, and circulates around Antarctica, and then moves northward to the Indian, Pacific, and Atlantic basins. It can take a thousand years for water from the North Atlantic to find its way into the North Pacific.

19. Conveyor Belt

20. Upwelling
Occurs when the current flows from the sea floor up to the ocean surface
Most common along coastlines where strong winds blow offshore
Winds will blow the surface water away from the land
Cold, deep water then rises from below to replace the surface water that has been moved out to sea

21. Upwelling
Upwellings have an important effect on the ecology of the sea and on human fisheries
Upwelling water contains a large amount of nutrients from the sea floor
Plants living near the surface will use these nutrients to grow
Plants then attract fish to areas of upwelling

23. El Nino and La Nina

24. El Nino Webquest