1. Surface Currents Flow of water in the uppermost layer of the ocean driven by wind

2. Wind and Currents Strongly affected by the Coriolis Effect Strongly affected by the Coriolis Effect –The eastward rotation of earth on its axis deflecting the moving water or air away from its initial course http://www.classzone.com/books/eart h_science/terc/content/visualizations/e s1904/es1904page01.cfm http://www.classzone.com/books/eart h_science/terc/content/visualizations/e s1904/es1904page01.cfm http://www.classzone.com/books/eart h_science/terc/content/visualizations/e s1904/es1904page01.cfm http://www.classzone.com/books/eart h_science/terc/content/visualizations/e s1904/es1904page01.cfm

3. Which direction??

4. Wind Patterns Driven by solar heating Driven by solar heating –Warm at equator –Cold at poles –Molecules move from warm to cold Also affected by moisture (density) Also affected by moisture (density) As warm air rises at equator, new air rushes in to replace it  wind As warm air rises at equator, new air rushes in to replace it  wind

5. Formation of Trade Winds

6. There are 6 atmospheric circulation cells:

7. Winds are bent by Coriolis Effect (45 o ) Winds are bent by Coriolis Effect (45 o ) http://www.mhhe.com/biosci/genbio/tlw3/ eBridge/Chp29/animations/ch29/global_wi nd_circulation.swf http://www.mhhe.com/biosci/genbio/tlw3/ eBridge/Chp29/animations/ch29/global_wi nd_circulation.swf http://www.mhhe.com/biosci/genbio/tlw3/ eBridge/Chp29/animations/ch29/global_wi nd_circulation.swf http://www.mhhe.com/biosci/genbio/tlw3/ eBridge/Chp29/animations/ch29/global_wi nd_circulation.swf

8. Surface Currents Major wind fields create sea surface currents Major wind fields create sea surface currents Uppermost layer of surface water moves at angle 45 o due to Coriolis effect Uppermost layer of surface water moves at angle 45 o due to Coriolis effect

9. Ocean Surface Currents Trade winds move toward the equator, equatorial ocean current produced move parallel to equator Trade winds move toward the equator, equatorial ocean current produced move parallel to equator

10. Due to Coriolis effect, the surface currents combine into circular systems  gyres Due to Coriolis effect, the surface currents combine into circular systems  gyres –Northern Hemisphere – clockwise –Southern Hemisphere - counterclockwise

12. Ekman transport Top layer of water pushes on water below it but bends slightly to right Top layer of water pushes on water below it but bends slightly to right Processes continues down through water column creating Ekman spiral Processes continues down through water column creating Ekman spiral

13. Effect of wind decreases w/ depth Effect of wind decreases w/ depth –Affects top 100 m (Ekman layer) –Overall Ekman layer moves at 90 o from wind direction Effects of Ekman Transport

14. Climate Regulation Water transports heat Water transports heat Ocean Currents act like global thermostat: Ocean Currents act like global thermostat: –Solar heat from Equator carried to higher latitudes warms poles –Cold water currents cool tropics

15. Currents Affect Organisms Surface temp higher on western side of ocean Surface temp higher on western side of ocean –Currents carry warm water away from Equator –Tropical organisms found at higher latitudes on west side of ocean Cold-favoring organisms live closest to equator on eastern side of oceans Cold-favoring organisms live closest to equator on eastern side of oceans