Ocean Currents and gyres - PowerPoint PPT Presentation

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Ocean Currents and gyres

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  1. Ocean Currents and gyres The “rivers” of the sea.

  2. TYPES OF CURRENTS Surface Currents Deep Currents Perpendicular to surface (vertical) Parallel to surface of ocean (horizontal)

  3. What causes them? Wind –the constant blowing of global winds causes surface currents. ***Primarily for surface currents. 2) Changes in sea level – underwater mounds and landforms actually push water up or let it fall deeper down. This causes pressure differences that make water move. 3) Density variations – density differences cause water to want to move from one area to another. (vertically) ***primarily for deep currents.

  4. Gyre – a circular flow of ocean currents as they contact land and turn. In the northern hemisphere, gyres turn right (clockwise) In the southern hemisphere, gyres turn left (counter-clockwise)

  5. THE CORIOLIS EFFECTThe earth’s rotation is what causes them to curve in a specific direction. Curves to the right of original direction. Curves to the left of original direction.

  6. -Density changes due to salinity and temperature changes will cause water to sink -When water sinks, the area that it left now needs to be replaced. -This water is replaced by deep ocean water, causing deep ocean currents.

  7. How do we know about these currents? OR We can literally float around in them and make observations. We can float a buoy in one spot and measure the waters movement as it passes.

  8. WHY study ocean currents? Who cares? What/who do they affect? Redistributes heat Redistributes pollution Global weather/climate (heat) Carries plankton/food Affects shipping and vessels Upwelling (mixing)