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Wave slideshow

  1. 1. Chapter 10 and 11
  2. 2. What is the most common force of water waves?
  3. 3. Anatomy of a wave
  4. 4. Know what these terms mean! Crest Trough Wavelength Wave Height Amplitude Period
  5. 5. Wave Motion and Wave Speed How do particles move through waves? Orbit is created where particles move up and down or forward and backward How different below the surface? Less energy
  6. 6. Source: http://www.srh.noaa.gov/jetstream//ocean/wave_max.htm
  7. 7. Deep-Water Waves How is a deep water wave classified? Water must be deeper than half of the wave length Storm center waves move outward Middle of storm center is a mixture of wave heights, lengths and periods Long waves leave storm center and move faster than most waves = Dispersion Waves that group together = wave trains
  8. 8. Wave Interaction What happened during “The Perfect Storm”? Constructive Interference or amplification Waves can pass through, amplify, or cancel each other out Also can come at angles to each other Wave trains can synchronize, crest and create smaller waves http://www.youtube.com/watch?v=dpZLGbvIzx0
  9. 9. Wave Interaction
  10. 10. Wave Speed Waves speed = celerity S = wavelength/wave period or C = L/T Remember length is distance and period is time!
  11. 11. Wave Height What affects wave height? Wind speed, duration and fetch Fetch = distance over the water that wind blows to create waves moving in the same direction All three variables must combine to make BIG WAVES
  12. 12. The Beaufort Scale source: http://www.aoml.noaa.gov/hrd/tcfaq/D10.html Relate height and period to speed, duration and fetch = Beaufort Scale of sea state
  13. 13. Wave Steepness How is steepness measured on a wave? Steepness = Height/Length How do waves behave differently in shallow water? Water orbits compress and forward speed of wave reduced Shallow water wave is wave that enters depth 1/20th of wave length Wave crests bend as approach shore due to difference of speed between ends of wave crests (i.e. shallow end slow and deep end fast) = refract
  14. 14. Shallow Water Wave
  15. 15. Shallow Water Waves
  16. 16. Diffraction is when a wave travels toward a barrier and through a small opening = waves radiate outward Important information for the design of harbors and safe mooring Remember Polynesians used wave patterns to travel and locate other islands Length and speed controlled by depth
  17. 17. The Surf Zone What affects how waves behave in the surf zone? Depth of water and shape of shoreline Look for the three different shore line examples in your book Narrow steep sloped beaches produce bigger waves for surfers!
  18. 18. The Music of Surfing http://www.youtube.com/watch?v=urtbRmPuLpk http://www.youtube.com/watch?v=fP1QK0XCt1U http://video.tiscali.it/canali/truveo/1673452417.html
  19. 19. Tsunamis What produces tsunamis wave? Earthquakes or sudden movement of earth’s crust Results in extremely long waves (54-108 miles long) At point of origin boat may not feel full force (3-6 ft swell) When path of wave blocked by coast or island the height builds rapidly Leading edge may be a trough or crest
  20. 20. Tsunami Videos http://oceanservice.noaa.gov/video/stormsurge.mov http://www.youtube.com/watch?v=i6XWVBi0dOo http://www.youtube.com/watch?v=Gbq412haY1c http://www.youtube.com/watch?v=AlPqL7IUT6M
  21. 21. What is the driving force behind tides? Mainly the gravitational pull of the moon Three types of tides:  Diurnal = one high and one low  Semi-diurnal = high and low twice a day  Mixed = high at different heights and low different heights
  22. 22. What are the tides in WA?
  23. 23. http://courses.washington.edu /ocean101/Lex/Lecture17.pdf
  24. 24. Semi-diurnal tides
  25. 25. http://library.thinkquest.org/C003124/en/sunmo on.htm
  26. 26. What are the main forces that come into play? Earth and moon and centrifugal force Earth’s water covering is malleable and pulls or bulges toward the gravitational pull of the moon. As the moon moves position so to follows the tidal bulge At the same time the centrifugal force acting on the Earth pulls opposite the moon producing two bulges at opposite ends and two troughs in between
  27. 27. http://www.youtube.com/watch?v=Rn_ycVcyxlY
  28. 28. What is a flood tide and what is an ebb tide? Flood is a rising tide and ebb tide is a falling tide Low Tide = lowest height reached during the tidal cycle High Tide = greatest height reached during that tidal cycle Minus Tide falls below the mean value
  29. 29. Tidal Day The point at which the tidal cycle begins is 50 minutes later each day due to the interplay of the earth and moon’s orbits Therefore, a tidal day or cycle is 24hrs and 50 minutes
  30. 30. Spring Tides and Neap Tides When do spring and neap tides occur? Spring Tides occur when the moon and sun are on the same side of the earth creating more pull or bulge and thus higher tides than normal Neap Tides occur when the moon is in it’s first quarter and it is located at right angles to the earth and sun
  31. 31. Diurnal Tides When the moon or sun N. or S. of equator one bulge found in Northern and other in Southern Hemisphere thus one high and one low tide Sun moves from Tropic of Cancer to Tropic of Capricorn each year and therefore more diurnal tides during summer and winter solstices
  32. 32. Are tides short or long waves from what you have learned thus far? Long waves that behave like shallow-water waves Speed of approximately 200 m/sec Tidal friction created between tidal currents and sea floor Tidal waves create tidal turbulence through out water column and thus mixing nutrients from deeper levels to upper levels of the column Tidal waves reflect off of land masses and sometimes become standing waves
  33. 33. Predicting Tides and Tidal Currents How are tides predicted? Water level stations at coastal locations that measure tidal changes for several years Primary tidal stations run for at least 19 years to coincide with 18.6 period year of the moon Mean tidal levels gathered from the data with astronomical information NOAA source of tide tables Private companies have taken over the dissemination of information
  34. 34. Tropical Atmosphere Ocean Bouy
  35. 35. Weather Bouy
  36. 36. Tidal Bores What is a tidal bore and where do they occur? In shallow bays of high tidal amplitude Bay of Fundy
  37. 37. Bay of Fundy – High and Low Tides
  38. 38. Energy from Waves and Tides How can energy be harnessed from waves and tides?  Changing water level to lift an object  Using orbital movement of water  Using rising water to compress air in a chamber Power of all the waves in the ocean 3000 power produced at Hoover dam Scotland and Norway currently use wave power to generate electricity
  39. 39. What is the cost of capturing the wave energy that usually shapes coasts? Energy from tides only in areas of high tidal range Rance River in France and Annapolis River in Nova Scotia Expensive to produce compared to other sources of power New efforts underway in England, Scotland and Norway http://video.techrepublic.com.com/2422-13792_11- 193651.html In the United States?
  40. 40. unit1_3.htm
  41. 41. http://www.scientificamerican.com/article.cfm?id=ocean-wave- tidal-power