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Oceans Name the oceans 1. 2. 3. 4. 5. 6. 7. Name the oceans Just joking. There is only one ocean. Name the parts of the ocean 1. 2. 3. 4. 5. 6. 7. North Atlantic South Atlantic North Pacific South Pacific Indian Antarctic Arctic? Name the parts of the ocean 1. 2. 3. 4. 5. 6. 7. North Atlantic South Atlantic North Pacific South Pacific Indian Antarctic Arctic? Name the parts of the ocean North Atlantic South Atlantic Arctic? Antarctic North Pacific Indian South Pacific Name the parts of the ocean Statistics • • • • Area—~ 340 million km2 (71% of surface) Average Depth—3800m Salinity—35g salt/kg of ocean water (varies) Average Temperature--Surface: 17oC (63oF) Deep: 3oC (37oF) Temperature • Where would you find warmer surface water? Temperature • Where would you find warmer surface water? Cooler Warmer Cooler Temperature • Surface water is warmer than deep water • From 200 m to 1000 m deep, temperature drops sharply. • This region is called the thermocline Density • Surface water is less dense than deeper water • From 100 m to 1200 m, the density rises sharply • This region is called the pycnocline What causes density differences? What causes density differences? Temperature and salinity What causes density differences? Temperature and salinity Cooler water is more dense Saltier water is more dense Where will you find the saltiest surface water? Where will you find the saltiest surface water? Surface water in the tropics. Evaporation is the highest there. …but it’s warm water Surface water near the poles. Freezing sea water freezes the water and leaves the salt. Why does ocean water move? 1. 2. 3. Why does ocean water move? 1. Wind 2. Density differences 3. Coriolis effect Why does ocean water move? 1. Wind—surface water moves in the direction of the wind 2. Density differences 3. Coriolis effect Why does ocean water move? 1. Wind—surface water moves in the direction of the wind 2. Density differences—more dense water sinks under less dense water 3. Coriolis effect Why does ocean water move? 1. Wind—surface water moves in the direction of the wind 2. Density differences—more dense water sinks under less dense water 3. Coriolis effect—water flowing north or south bends to the right in the northern hemisphere. Why does deep ocean water move? Why does deep ocean water move? • Density differences, mainly. • Masses of water sink near the poles, traveling thousands of kilometers before mixing with other layers • The tides also affect deep water. The thermohaline current (deep) Surface currents Surface currents Currents have to turn when they hit a continent Surface currents Cold currents come from polar waters Surface currents Warm currents come from equatorial waters Surface currents Currents heading towards the poles bend east Surface currents Currents heading away from the poles bend west Surface currents Currents circle clockwise in the northern hemisphere Surface currents Currents circle counterclockwise in the southern hemisphere Warm currents include: Warm currents include: The Gulf Stream, Alaska, Brazil and East Australia Currents Cold currents include: Cold currents include: The California, Peru, Canary and West Australia Currents http://www.montereyinstitute.org/no aa/lesson08.html Ekman Drift • Winds blow east or west in bands by latitude (PS: winds are named by where they come from) Ekman Drift • The water below the surface pulls to the right in the northern hemisphere Ekman Drift • Ekman drift causes a mound of water to pile up between the bands of wind. Geostrophic Currents • Coriolis forces and Ekman drift force water to move in a circle • These currents are called geostrophic currents Why does ocean water move? 1. Wind 2. Density differences 3. Geostrophic forces 4. Tides Gyres The circular pattern formed is called a gyre. There are about 5 major gyres, and 10 minor ones Gyres Gyres carry heat around. Trash collects in the center of a gyre The speed of the water depends on the width of the current It takes several years for water (and floating objects) to be carried around a gyre. Gyres Upwelling and downwelling • Ekman drift near a continent can move water away from shore. Water comes up from below to replace it. Upwelling and downwelling • Ekman drift near a continent can move water away from shore. Water comes up from below to replace it. Reverse the wind, or place the continent on the other side to force downwelling El Niño El Niño • …upwelling at the west coast of South America decreases… El Niño • …upwelling at the west coast of South America decreases… • …leading to warmer surface waters… El Niño • …upwelling at the west coast of South America decreases… • …leading to warmer surface waters… • …reversing the prevailing winds… El Niño • …upwelling at the west coast of South America decreases… • …leading to warmer surface waters… • …reversing the prevailing winds… • …changing rainfall and temperature patterns over the entire western hemisphere. Walker Circulation • Normal wind pattern Walker Circulation • El Niño events reverse the wind pattern Weather vs. Climate Weather vs. Climate Short term Long term Weather vs. Climate Short term Long term Hourly Daily Weekly Yearly Over many years— using historical or geologic data Weather vs. Climate • Both include: – Total precipitation – Type of precipitation – Temperatures – Wind patterns – Seasonal variations in all of the above Teleconnections --when the cause is far removed from the effects Teleconnections --when the cause is far removed from the effects With weather patterns: -the position of the jet streams -moisture content of air masses and -temperature of air masses can cause effects far away Temperature anomalies Temperature anomalies Rainfall anomalies