exam3geo - Chapter 18.3- OCEAN WATER AND CURRENTS What...

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Chapter 18.3- OCEAN WATER AND CURRENTS What drives the ocean currents? Currents - a well-defined streams of ocean water that flows or circulates at velocities of up to several km/hr may be driven by tides, winds or differences in density. Surface currents are driven by wind and are deflected by the Coriolis Effect . The vertical upwelling and downwelling of water create deep currents. Some of this movement is thermohaline circulation , a consequence of variations in temperature and salinity. Occurs at 2 levels: Surface Currents : affect the upper hundred meters of water o 1. Winds blow over oceans 2. Water is pushed by the winds 3. Water piles-up in the center 4. Water flows down from the center o does not flow smoothly, displays some turbulance o eddies : isolated swirls or ring-shaped currents of water form along the margins of currents o gyres : surface currents trace out these large circular flow patterns, clockwise in the northern seas and counterclockwise in southern seas. Deep Currents : “global conveyor belt” keep even water at the bottom of the sea in motion, circulates in the veritical direction. o Downwelling - occurs when surface water moves toward coast, oversupply of water develops along shore and excess water must sink o Upwelling : occurs when surface water moves away from coast, deficit of water develops near coast and water rises to fill in the gap What is coriolis and how does it affect the ocean currents? Coriolis Effect - since the earth is a rotating sphere, moving objects (as viewed from earth) are directed either to the right or left. Causes surface currents in the Northern Hemisphere to veer toward the
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exam3geo - Chapter 18.3- OCEAN WATER AND CURRENTS What...

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