“Keeping It Current”

Ocean currents Mass of moving water Distribute heat and nutrients around the globe 2 Types: Surface currents Deep currents

Surface Currents Caused by strong winds (Global Winds) blowing over the ocean Extend about 100-200 meters down into the ocean Curl into giant clockwise whirlpools in NH and counterclockwise whirlpools in SH, (because of the Earth’s rotation-Coriolis Effect).

Deep Currents Caused by differences in water Density – THERMOHALINE CIRCULATION What causes differences in water density? Differences in temperature (warm and cold) Differences in salinity (high salt and low salt)

Where is water most dense? Sea water can become MORE DENSE when: It’s cold or cooling It increases in salinity (salt) Or it is both cold and salty Densest water is found at the polar regions The most dense water sinks to the bottom of the ocean and is COLD and SALTY

Gyres Form circular currents due to the Coriolis Effect Clockwise (NH) Counter-clockwise (SH)

Ocean Gyres ****Five Major gyres**** One in each major ocean basin 1. North Atlantic - clockwise 2. South Atlantic – counter clockwise 3. North Pacific - clockwise 4. South pacific - counter clockwise 5. Indian Ocean - counter clockwise

Boundary Currents Western Boundary Currents (warm): • Along eastern continental coasts • Carry warm water away from equator • Narrowest, fastest, and deepest surface currents • Ex: The Gulf Stream in the North Atlantic and the Kuroshio Current in the North Pacific

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Boundary Currents Eastern Boundary currents (cool): Along western continental coasts Carry cool water toward the equator. Along the eastern side of the ocean basin Ex: California Current in the North Pacific and the Peru Current in the South Pacific.