Lo5 waves,currents,coasts

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Lo5 waves,currents,coasts

  1. 1. Earth’s AtmosphereEarth’s Atmosphere and Oceansand Oceans Currents, Waves and CoastlinesCurrents, Waves and Coastlines
  2. 2. Ocean Currents:Ocean Currents: the motions of oceansthe motions of oceans (sorry, couldn’t resist the bad rhyme!)(sorry, couldn’t resist the bad rhyme!) • Causes:Causes: – Tides – gravitational pull from moon and sunTides – gravitational pull from moon and sun causes predictable tidal currentscauses predictable tidal currents – Wind – Surface CurrentsWind – Surface Currents – Thermohaline Circulation (density differences)Thermohaline Circulation (density differences) = Deep Currents= Deep Currents
  3. 3. Surface CurrentsSurface Currents • Rotate due to CoriolisRotate due to Coriolis • Create Gyres –circles of moving waterCreate Gyres –circles of moving water within the oceanswithin the oceans – Clockwise – Northern HemisphereClockwise – Northern Hemisphere – Counterclockwise – Southern HemisphereCounterclockwise – Southern Hemisphere
  4. 4. GyresGyres • GyresGyres
  5. 5. Gyres and Surface CurrentsGyres and Surface Currents
  6. 6. UpwellingUpwelling • formation of upwellingformation of upwelling
  7. 7. What is upwelling?What is upwelling? • Subsurface water rises to surfaceSubsurface water rises to surface • Characteristics:Characteristics: – ColderColder – Rich in nutrientsRich in nutrients – Biologically productive = Good fishingBiologically productive = Good fishing
  8. 8. Major Areas of UpwellingMajor Areas of Upwelling
  9. 9. Global Conveyor beltGlobal Conveyor belt Thermohaline CirculationThermohaline Circulation BeginsBegins
  10. 10. • Surface and Deep Ocean CurrentsSurface and Deep Ocean Currents
  11. 11. Idealized “conveyor belt”Idealized “conveyor belt” model of oceanmodel of ocean circulationcirculation
  12. 12. Ocean WavesOcean Waves • What makes big waves?What makes big waves? – Wind – speed and durationWind – speed and duration – Fetch – distance that a wave has to growFetch – distance that a wave has to grow
  13. 13. Breaking WavesBreaking Waves • Friction between sea floor and waterFriction between sea floor and water • Waves become too steepWaves become too steep • Breakers formBreakers form
  14. 14. The basic parts andThe basic parts and movement of a non-movement of a non- breaking wavebreaking wave
  15. 15. Changes that occur whenChanges that occur when a wave moves onto shorea wave moves onto shore
  16. 16. Beach Construction/DestructionBeach Construction/Destruction • Swash and BackwashSwash and Backwash
  17. 17. Wave refraction along anWave refraction along an irregular coastlineirregular coastline
  18. 18. Beach drift andBeach drift and longshore currentslongshore currents
  19. 19. Example of Longshore DriftExample of Longshore Drift Shoreline ErosionShoreline Erosion – Tucker Island Lighthouse, NJ, 1927Tucker Island Lighthouse, NJ, 1927
  20. 20. Rip CurrentsRip Currents • Rip CurrentsRip Currents
  21. 21. Coastal Erosion CausesCoastal Erosion Causes • Storm wavesStorm waves • Long shore driftLong shore drift • Storm surgeStorm surge • Winter stormsWinter storms • Human-Induced CausesHuman-Induced Causes
  22. 22. Human-Induced CoastalHuman-Induced Coastal ErosionErosion • Removing vegetation and protectiveRemoving vegetation and protective dunesdunes • Building “protective” structuresBuilding “protective” structures • River modification and dredgingRiver modification and dredging
  23. 23. JettiesJetties
  24. 24. Which direction is longshore drift?Which direction is longshore drift?
  25. 25. Which direction is the longshore drift?Which direction is the longshore drift?
  26. 26. SummerSummer –– The lower waves of summer build sandThe lower waves of summer build sand onshore and widen the beach.onshore and widen the beach.
  27. 27. WinterWinter -- Higher winter waves moveHigher winter waves move sand offshore and narrow the beach.sand offshore and narrow the beach.
  28. 28. Dune StabilizationDune Stabilization
  29. 29. COASTAL EROSIONCOASTAL EROSION
  30. 30. Marine TerracesMarine Terraces
  31. 31. Sea archSea arch
  32. 32. Sea stackSea stack
  33. 33. Coastal DepositionCoastal Deposition
  34. 34. SpitSpit
  35. 35. Baymouth BarBaymouth Bar
  36. 36. Aerial view of a spit andAerial view of a spit and baymouth bar along thebaymouth bar along the Massachusetts coastlineMassachusetts coastline
  37. 37. Barrier IslandsBarrier Islands • Long, narrow islands paralleling shorelineLong, narrow islands paralleling shoreline • Protected salt water bays behindProtected salt water bays behind • Protect mainlandProtect mainland • Naturally transientNaturally transient
  38. 38. Fire Island migrationFire Island migration
  39. 39. Miami Beach beforeMiami Beach before beach nourishmentbeach nourishment
  40. 40. Miami Beach afterMiami Beach after beach nourishmentbeach nourishment
  41. 41. EstuariesEstuaries
  42. 42. MajorMajor estuariesestuaries along thealong the East CoastEast Coast of theof the UnitedUnited StatesStates
  43. 43. The EndThe End
  44. 44. TomboloTombolo

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