1. WAVES disturbance caused by the movement of energy from a source through some medium (solid, liquid or gas). THERE ARE MANY DIFFERENT SIZES AND SHAPES OF WAVES

2. Global Wave Height

4. Rogue Wave

5. Hawaii, 66’ wave

7. Types of Waves Chaotic Waves Ocean Swells Ocean Breakers

8. Swell – mature, regular, wind waves

9. WAVES Because the wave form moves forward these are called progressive waves

10. Wind wave – ratio of height to wavelength (wave steepness) = 1 to 7

12. WAVES The energy is moving at the speed of the wave, but NOT the water

13. Fig 9-1, g

14. Fig 9-3, p.201

15. Orbits The diameter of the orbits diminishes rapidly with depth Wave motion in deep water is negligible past ½ the wavelength

17. Fnft

18. WAVES The parcel of water moves in a circular motion = orbit water is displaced very little across the sea surface as the illusion of a wave suggests

19. Components… Crest Trough Wavelength Height Frequency Fetch Wavebreak Refraction Period

20. Fig 9-2, g

21. Wave fetch – uninterrupted distance over which the wind blows w/o significant change in direction.

22. Fig 9-15, g Wavebreak – ratio of wave height to water depth is 3 to 4

23. fnft

24. Fnft

25. Wave Refraction When waves do not approach parallel to shore… The wave line will bend to become more parallel to shore

26. Fnft Wave refraction

27. Wave crests bend 90 degrees as they move around point (Hawaii) = refraction

32. Stoke’s Drift or Mass Transport Small net movement of water in the direction of the wave

33. Figure not from book

34. Classifying Waves disturbing force = the energy that cause waves to form restoring force = the dominant force trying to return surface water to flatness wavelength

35. Wave energy as a function of wave period

37. fnfb

38. types of waves “swell” (capillary wave) Shallow water wave Deep water wave

39. Wave Types Capillary waves –Wind –Surface tension – <1.73cm

40. Fig. 9-6, g

41. Capillary waves interrupt the smooth surface, deflect upward, Slow & cause winds energy to be transferred into the water. A= crest; B=trough

42. Swell – mature, regular, wind waves

43. Fnft Deep water wave Shallow water wave

44. Deep vs Shallow Water waves The orbits of water molecules in a wave are circular only when the wave is in deep water A wave cannot “feel” the bottom if it is in water deeper than ½ its wavelength = a deep water wave

45. fnfb

46. Deep vs Shallow Water Waves ONLY WIND WAVES CAN BE DEEP WATER WAVES

47. Deep vs Shallow Water Waves Shallow water waves = moving in water shallower than 1/20 it wavelength Water at the bottom moves back and forth

48. fnfb

49. Deep vs Shallow Water Waves Transitional waves = travel through water deeper than 1/20 their wavelength and shallower than ½ its wavelength

50. fnfb

51. Fig. 9-5, g

52. How waves break at shore... A deep water waves feels bottom and becomes a transitional wave orbits become elliptical crests become peaked wave height increases wave slows down wave length decrease

53. Wavebreak – ratio of wave height to water depth is 3 to 4

54. fnft

55. How waves break at shore... The wave becomes too high for its wavelength and the wave breaks The surf zone is the region between the breaking waves and the shore.

57. INTERFERENCE Destructive interference = cancellation effects of subtraction –When a wave crest and another wave’s trough coincide

58. INTERFERENCE Constructive interference = addition effects that form large crests and deep troughs –When crests coincide

60. Constructive Interference

62. Types of Waves Tsunamis Seismic Sea Waves

63. Types of Waves Tsunamis – long wavelength, shallow water progressive waves caused by rapid displacement of ocean water. This is caused by sudden vertical movement of earth along a fault line, causing a Seismic Sea Wave. Origination on seafloor, a “problem” for continental populations if this is close to land or in a confined space!

64. Tsunami A tsunami can be a wave w/ a wavelength up to 125 miles! Remember the deepest ocean basin is 7(+) miles deep…if a wave = ½ wavelength it’s still not enough “room” to move (do the math!) Problem: a tsunami wave can reach a height of over 100’

65. Tsunamis originate from earthquakes, volcanic explosions, or submarine landslides. On December 26, 2004, an earthquake with a magnitude of over 9.0 on the Richter scale triggered a megatsunami that affected coastlines throughout the Indian Ocean.

66. Fig 9-27, g

67. Fig 9-21, g 1946 Hawaiian tsunami

68. Fnft Sequence: 1957 Hawaii tsunami 5 hrs. earlier = earthquake…

69. Fnft 15 minutes later

70. Fnft 2 hrs. total duration = 56’ total wave height, $25 million in damages

77. Fig 9-26, g

78. Fig. 9-26, g