Ocean currents Power Point Slides


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Ocean currents Power Point Slides

  1. 1. Ocean Currents “Rivers in the Ocean”
  2. 2. Currents • Current – a large stream of moving water that flows through the ocean. Capable of moving large amounts of water long distances. • Surface Currents – Affect water to a depth of several hundred meters and are driven mainly by wind. – Currents move in circular patterns in each of the five major ocean basins.
  3. 3. Currents • Factors that affect currents – Sun’s heat – Earth’s winds – Earth’s rotation • Coriolis effect – the effect of Earth’s rotation on the direction of winds and currents – This is why currents in the Northern Hemisphere are clockwise, and those in the Southern Hemisphere run counter-clockwise
  4. 4. Gyres Explained http://youtu.be/CqZjvD_Xs4k
  5. 5. Currents • The largest and most powerful current in the North Atlantic Ocean is the Gulf Stream. – Caused by strong winds coming from the west (the same ones that move weather fronts from west to east) – More than 30 km wide and 300 m deep – Carries warm water up the East Coast Surface Current http://youtu.be/YCorkyBe66o
  6. 6. Currents • Deep Currents – caused by differences in density • rather than by surface winds Density of ocean water depends on two factors – Temperature (cold water = more dense = sinks to bottom) – Salinity (amount of salt, more salt = more dense = sinks to bottom) • Warm water surface currents move water from the equator toward the poles, where the water gets very cold.
  7. 7. Currents • As ice forms at the poles, the salinity of the water increases. • When temperature decreases and salinity increases, the density of the water increases. • This causes the water to sink to the bottom of the ocean floor. • Deep currents move much more slowly than surface currents.
  8. 8. Currents • Upwelling – the upward movement of colder water from the ocean depths. • Caused by the winds. – Wind blows the warm surface water away, causing cold water to rise up to replace it.
  9. 9. Currents • Upwelling also brings up – Tiny ocean organisms – Minerals – Other nutrients • Without this, the surface waters would have very little nutrients. • Upwelling zones are typically home to enormous schools of fish
  10. 10. Currents • One major area of upwelling is in the Pacific Ocean off of South America. • Upwelling occurs when strong winds from the Andes Mountains sweep across the ocean. – This creates a fishing area that is important to millions of people who depend on it for food and jobs.
  11. 11. Review • Surface Current - http://youtu.be/YCorkyBe66o
  12. 12. Quick Check Review • What are the two types of currents found in the ocean? • What is the Coriolis Effect? • What three things does upwelling bring to the surface?
  13. 13. Mr Parr’s Current Song • http://youtu.be/NsdH_NRM-CU