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9th  Grade  Chapter 4  Lesson 2
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9th Grade Chapter 4 Lesson 2



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9th Grade Chapter 4 Lesson 2 Presentation Transcript

  • 1. 9 th Grade Chapter 4 Lesson 2 Pgs. 92-96 For Student Use Only
  • 2. Ocean Currents
    • Countercurrents:
      • When surface currents flow other places water from other places rushes in to meet the currents.
      • Countercurrent- the current filling the void when surface water moves away.
        • Countercurrents can exist on the surface or in a subsurface area
  • 3. Ocean Currents
    • http://www.dorlingkindersley-uk.co.uk/nf/ClipArt/Thumbnail/0,,239020,00.html
  • 4. Ocean Currents
    • Waves and Related Phenomena
      • Waves: Rhythmic movement of water back and forth that transfer energy
        • Wave Parts
          • Crest- high point
          • Trough- low point
          • Period- time between waves
  • 5. Ocean Currents
    • Wave Formation:
      • Three main factors determine the size of these waves:
        • Speed of the wind
        • The length of time wind blows
        • The expanse of open water over which the wind blows
  • 6. Ocean Currents
    • Waves:
      • Choppy- gusty winds cause waves that are different sizes in different sizes and directions
      • White Caps: strong winds that whip waves into a spray with a foamy crest
      • Ocean Swells: gentle rolling waves
  • 7. Ocean Currents
    • Wave Motion
      • Water only moves a few feet, energy moves to shore
        • Breaker: Water moves quicker at top and slower at bottom when water is shallow, the then topples over itself
        • Surf: Foaming water that goes up the beach
  • 8. Ocean Currents
    • Currents:
      • Undertow- Small stream of water that is going from shore back to sea
      • Longshore current- When there is a sandbar and water that flows parallel to the beach
      • Rip Current (Rip Tide)- surface current that carries large amounts of water back to sea through incoming breakers
  • 9. Ocean Currents
    • Waves:
      • Tsunamis- gigantic waves that are caused by earthquakes, volcanic explosion, or undersea landslides.
      • These waves can be 200 ft. tall as they build up closer to shore.
  • 10. Ocean Currents
    • Tides:
      • Predictable currents
      • Caused by the moon’s gravity
        • High Tide- moon’s gravity is strongest
        • Low Tide- side not experiencing moon’s gravity
        • Spring Tide- sun and moon team up to pull the water
        • Neap Tide- weak tides- moon and sun at 90 degree angles