Helgers, ESC 101

1. Earth’s AtmosphereEarth’s Atmosphere
and Oceansand Oceans
Currents, Waves and CoastlinesCurrents, Waves and Coastlines

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. 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. GyresGyres
• GyresGyres

5. Gyres and Surface CurrentsGyres and Surface Currents

6. UpwellingUpwelling
• formation of upwellingformation of upwelling

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. Major Areas of UpwellingMajor Areas of Upwelling

9. Global Conveyor beltGlobal Conveyor belt
Thermohaline CirculationThermohaline Circulation
BeginsBegins

10. • Surface and Deep Ocean CurrentsSurface and Deep Ocean Currents

11. Idealized “conveyor belt”Idealized “conveyor belt”
model of oceanmodel of ocean
circulationcirculation

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. 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. The basic parts andThe basic parts and
movement of a non-movement of a non-
breaking wavebreaking wave

15. Changes that occur whenChanges that occur when
a wave moves onto shorea wave moves onto shore

16. Beach Construction/DestructionBeach Construction/Destruction
• Swash and BackwashSwash and Backwash

17. Wave refraction along anWave refraction along an
irregular coastlineirregular coastline

18. Beach drift andBeach drift and
longshore currentslongshore currents

19. Example of Longshore DriftExample of Longshore Drift
Shoreline ErosionShoreline Erosion
– Tucker Island Lighthouse, NJ, 1927Tucker Island Lighthouse, NJ, 1927

20. Rip CurrentsRip Currents
• Rip CurrentsRip Currents

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. 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. JettiesJetties

26. Which direction is longshore drift?Which direction is longshore drift?

27. Which direction is the longshore drift?Which direction is the longshore drift?

28. SummerSummer ––
The lower waves of summer build sandThe lower waves of summer build sand
onshore and widen the beach.onshore and widen the beach.

29. WinterWinter -- Higher winter waves moveHigher winter waves move
sand offshore and narrow the beach.sand offshore and narrow the beach.

30. Dune StabilizationDune Stabilization

31. COASTAL EROSIONCOASTAL EROSION

32. Marine TerracesMarine Terraces

33. Sea archSea arch

34. Sea stackSea stack

35. Coastal DepositionCoastal Deposition

36. SpitSpit

38. Baymouth BarBaymouth Bar

39. Aerial view of a spit andAerial view of a spit and
baymouth bar along thebaymouth bar along the
Massachusetts coastlineMassachusetts coastline

40. 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

41. Fire Island migrationFire Island migration

42. Miami Beach beforeMiami Beach before
beach nourishmentbeach nourishment

43. Miami Beach afterMiami Beach after
beach nourishmentbeach nourishment

44. EstuariesEstuaries

45. MajorMajor
estuariesestuaries
along thealong the
East CoastEast Coast
of theof the
UnitedUnited
StatesStates

46. The EndThe End

47. TomboloTombolo