Movements of the Ocean Ocean Currents

Types of Currents Surface Currents – currents that move on or near the surface of the ocean Global Wind Belts Location of Continents Rotation of the Earth Deep Currents – cold, dense currents far below the ocean’s surface Differences in density

Surface Currents - Factors Global Wind Belts Trade Winds (east  west) Westerlies (west  east) Polar Easterlies (east  west) Continental Barriers Continents cause the current to turn or divide

Global Winds Westerlies Trade Winds Trade Winds Westerlies Polar Easterlies Westerlies Trade Winds Trade Winds Westerlies Polar Easterlies

Surface Currents - Factors The Coriolis Effect Northern Currents – CLOCKWISE Southern Currents – COUNTER-CLOCKWISE

Coriolis Effect The curving of ocean surface currents is due to the Earth’s rotation.

Gyres: Huge circles of moving ocean surface currents. North Atlantic Gyre North Pacific Gyre South Pacific Gyre South Atlantic Gyre Indian Ocean Gyre

Water Density - Temperature As the water cools, the molecules get closer together. H2O H2O H2O H2O H2O H2O H2O H2O

Water Density - Temperature As the water cools, the molecules get closer together. This causes the water to become more dense and then will sink . H2O H2O H2O H2O H2O H2O H2O H2O

Water Density - Temperature As water warms, the molecules move away from each other. H2O H2O H2O H2O H2O H2O H2O H2O

Water Density - Temperature As water warms, the molecules move away from each other. This causes the water to be less dense and thus rises. H2O H2O H2O H2O H2O H2O H2O H2O

Water Density – Salinity Salt Water that contains salt is much denser than fresh water. When mixed with fresh water, the salt-water will sink. H2O H2O H2O Salt H2O H2O H2O Salt H2O H2O Salt

Water Density – Turbidity sediment Water that contains sediment is much more dense than fresh water. When mixed with “clean” water, the sediment-filled water will sink . This is called a turbidity current. H2O H2O H2O sediment H2O H2O H2O sediment H2O H2O sediment

Deep Ocean Currents Arctic (N Pole) Antarctica (S Pole) Warm, surface water cold, salty Antartic intermediate water North Atlantic deep water colder, saltier Antartic bottom water coldest, saltiest

Final Points: Surface currents are mostly affected by the wind. Other two factors that affect surface currents are location of continents and the Coriolis Effect. Deep currents are mostly affected by differences in density. Density of water is affected by temperature, salinity, and turbidity. (temperature matters the most)