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Exploring Wave Theory: An In-Depth Study on Ocean Waves

Dive into the development and applications of wave theory, analyzing natural waves, wave generation by winds, and wave interactions with the seafloor. Discover how mathematical descriptions allow predictions and forecasts of wave behavior under various circumstances. Explore the anatomy of waves, from wavelength and period to wave height and frequency. Learn how technology has revolutionized the study of waves, driving advancements in coastal engineering and vessel safety at sea. Unravel the mysteries of wave classification according to period, wavelength, frequency, and distributing force, and understand the significance of wave speed in predicting the impact of ocean waves on shorelines.

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Exploring Wave Theory: An In-Depth Study on Ocean Waves

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  1. Ocean Waves – Chp 10 Newest Extreme Wave (2006) Shark Park – off Channel Islands (San Miguel), CA

  2. Announcements • MIDTERM – Monday 4pm • Covers: Chapters 1-9 (excluding Chp 7), (not Todays) • 40 Multi Choice Qs • 5 Short answer Qs • All based on Lecture Notes/Qs • Bring GREEN Scantron (Bookstore) • #2 Pencil • HW-3 due Wed • HW-4, HW-5 (Nat. Bridges) due w/ Final • See Syllabus (website) for details

  3. Announcements • Your Homework • Do it! • If you don’t you loose 30-45% of your grade!!! • Turn it in! • DON”T WAIT TILL THE LAST MINUTE • HELP me to HELP YOU  • FYI HW-3, Skip Question d) on Page 6

  4. In Search of The Perfect Wave • Development of Wave Theory • What is a Wave? • Wave Theory • Analyzing Natural Waves • Wave Generation by Winds • Wave Interactions with Seafloor • Applications of Wave Theory OUTLINE

  5. In Search of The Perfect Wave (1966)

  6. In Search of The Perfect Wave • Development of Wave Theory • What is Wave? • Wave Theory • Analyzing Natural Waves • Wave Generation by Winds • Wave Interactions with Seafloor • Applications of Wave Theory OUTLINE

  7. Development of Wave Theory • Sir Isaac Newton (1642-1727) • First mathematical descriptions of waves, 1687Principia. • Proposed motion of water particles in a wave was circular • Franz Gerstner (1756-1832) • Develops 1st primitive wave theory • Particles traveling at the crest of wave move up/forward • Particles traveling at the trough of wave move down/backward • Motions traced a circle • Height @ surface = Height of Wave

  8. Development of Wave Theory • Ernst Weber (1795-1878) - Anatomy Professor • Wilhelm Weber (1804-1891) - Physicist • Built first WAVE Tank • Confirmed Gerstener’s circular Motions.

  9. Development of Wave Theory • WWII – Securing a Beach Head • Commanders wanted to Known type of Sea Conditions • Walter Munk • (Army Corp. Engineers) • With Harald Sverdrup (SIO) • Undertake Surf forecasting • Prediction of waves @ • Given location/time • 1960s_Munk’s lifes work • Deploys buoy devices etc. • Alaska  New Zealand • Munk Concludes • “Predictions of surfing conditions @ Honolulu possible, but from what I know of the Surfing profession I don’t suggest this as a lucrative enterprise” ??? . . .Before his time. . . But TODAY >>>>

  10. High Tech Surf Forecasts Now Exist • Web Cams, Reports, Forecasts/ Conditions etc. Surfers How Many? 1,736,000. -Rode a wave Once/year Estimates 5 -17 million. . . Overall 1960s ≤10,000 Matt Warshaw -Encyclopedia of Surfing

  11. Development of Wave Theory • Technology Drives the Study of Waves • Wave Heights, Wind speeds, mea. using Satellites & Buoys • Major Application behind Study of Waves • Application to Coastal Engineering Problems • Vessel Safety @ Sea

  12. In Search of The Perfect Wave • Development of Wave Theory • What is a Wave? • Wave Theory • Analyzing Natural Waves • Wave Generation by Winds • Wave Interactions with Seafloor • Applications of Wave Theory OUTLINE

  13. What is a Wave? • Waves result from the movement of E through a medium • = progressive waves • e.g. oceanic, seismic, sound waves Challenge Qs • What do Progressive Ocean waves arise from? • A disturbing Force • Force that Transmits E to the water column or surface via Wind or Earthquake • What are Waves from Episodic Events (e.g. Winds, Earthquakes) called? Free Waves - travel without any further influ. of Disturbing force • What are Waves from Continual Events (e.g. tides) called? • Forced Waves - under continual influence of disturbing force • (e.g. gravity from Moon or Sun) NOTE: Restoring Forces - Drain the Wave of it’s E

  14. What is a Wave? • Anatomy of a Wave • As E is transferred thru fluid the wave particles move in circular motion – aka orbital What is the Wavelength (λ)? Dist. b/w peaks (crests) Where is the Crest (Peak)? Where is the Trough (Valley) What is the Wave height (h)? Dist. b/w Crest - Trough λ h

  15. What is a Wave? • Anatomy of a Wave • What is the Period of a Wave? • Amount of Time passing b/w wave peaks • (how far are the peaks apart in time) • What is the Wave frequency? • How often peaks are passing same point in time

  16. What is a Wave? • Classification of Waves • According to their? • Period • Wavelength • Frequency • Distributing force

  17. What is a Wave? • Summary int

  18. In Search of The Perfect Wave • Development of Wave Theory • What is a Wave? • Wave Theory • Analyzing Natural Waves • Wave Generation by Winds • Wave Interactions with Seafloor • Applications of Wave Theory OUTLINE

  19. Wave Theory • Mathematical description of waves allows us to? • Predict behavior under diff. circumstances • Forecast their arrival on beaches • Surf forecasters make use of Wave theory to predict: • When & Where ocean waves have their greatest impact on shore.

  20. Wave Theory • Wave Speed (Velocity ~ V) • V = Wavelength / Period (Time) or V = λ/ T • Waves with different wavelengths and periods travel @ diff speeds • Since λ /T are proportional increases in Wind speed (C) lead to? • Increases in either Wavelength or Period or both • Note: the PERIOD does NOT change once Wave is formed

  21. Wave Theory calculating wavelength (λ) λ = T2g/2π • T = period time • g = Acceleration of gravity 9.8 m/s-2 or (32 feet/sec) • π = Pi ~ 3.1415 λ

  22. Wave Theory • What are Shallow water waves? • Waves traveling in H2O whose depth is less than one-twentieth (1/20) of the wavelength of the wave • What are deep water waves? • Waves whose propagation is NOT affected by the seafloor • What are intermediate water waves? • Surface waves in b/w the deep and shallow water approximations or Velocity (V) h/λ > 1/2 1/20 > h/ λ

  23. Wave Particle Motions • For Deep-water waves • Diameter of wave orbital • Based on Height • Challenge Question? • What happens to the diameter of • wave orbitals with depth? • They shrink (diminish) • disappear

  24. Wave Particle Motions • For Shallow-water waves • Diameter of wave orbital hits bottom • Becomes ovular b/c of: • friction/ drag effects etc. • e.g. notice Kelp moving Back/ fourth

  25. Wave Energy (E) E = 1/8 p g H2 • P = water Density • g = accel. of gravity • H = height of Wave • WHAT TO KNOW • Equation states that: • E increases as the Square of the waves Height • i.e. if you 2X the wave height  4X Wave E!!! • e.g. 6 m (20 foot) wave has 4 Xs as much E as 3 m (10 foot) wave ~> 20 feet ~ 10 feet

  26. In Search of The Perfect Wave • Development of Wave Theory • What is a Wave? • Wave Theory • Analyzing Natural Waves • Wave Generation by Winds • Wave Interactions with Seafloor • Applications of Wave Theory OUTLINE

  27. Analyzing Natural Waves • Wave Interference • Challenge Questions • What is produced when Crests/ troughs of Waves are offset? • Destructive interference • Cancel each other out • What is produced when two wave Crests overlap exactly? • Constructive interference • Doubling of wave height!

  28. Wave Interference • Summary

  29. Wave E Spectrum • Knowing H and frequency of Waves  wave E spectrum • @ given location / set of conditions exist? • Wave E spectrums

  30. In Search of The Perfect Wave • Development of Wave Theory • What is a Wave? • Wave Theory • Analyzing Natural Waves • Wave Generation by Winds • Wave Interactions with Seafloor • Applications of Wave Theory OUTLINE

  31. Wave Generation by Winds • From Atm. Winds to sea surface. . . . • Some wind E causes surface currents • Most Wind E  waves WIND WIND WIND WIND

  32. Wave Generation by Winds • Challenge Qs • What factors of wind determine the severity of the waves? • Speed of Wind • Length of Time in Blows (duration) • Distance over which it travels aka? • Fetch • Fetch

  33. From Calm to Fully Developed Sea • IT all starts with the Wind  swells • What are Swells? • Long wavelength - surface waves (group) • traveled long distances • (more stable then wind waves) Coming to a Shore Near YOU!!!!

  34. From Calm to Fully Developed Sea What is Wave Steepness ~ S ? • S = H/ λChallenge Q • What happens when steepness exceeds 1/7 or (0.142) ? • e.g. wavelength = 7m, wave height ≥ 1m the formation of White caps Discovered aboard FLIP 0.16

  35. In Search of The Perfect Wave • Development of Wave Theory • What is a Wave? • Wave Theory • Analyzing Natural Waves • Wave Generation by Winds • Wave Interactions with Seafloor • Applications of Wave Theory OUTLINE

  36. Wave Interactions with Seafloor • When deep water waves hit seafloor what happens? • 1) Friction slows down wave, decreases wavelength • 2) Orbitals become ovular • 3a) Height/steepness of Wave increases • 3b) Wave overly steep: S > 1/7  Breaks!

  37. Wave Interactions with Seafloor • Bathymetry Matters • RECALL TUBE – a product of an ocean floor http://www.youtube.com/watch?v=7BOhDaJH0m4&feature=related

  38. WAVES • Now the Whole Package Comes together • A SUMMARY of Some Concepts & Big Waves • http://www.kqed.org/quest/television/science-of-big-waves

  39. In Search of The Perfect Wave • Development of Wave Theory • What is a Wave? • Wave Theory • Analyzing Natural Waves • Wave Generation by Winds • Wave Interactions with Seafloor • Applications of Wave Theory OUTLINE

  40. SURF Forecasting • Confirming your knowledge • What are the major factors u need to form Considerable Waves? • Fetch (long distance for wind to blow) • Sustained High winds • Bathymetry effects • Most intense waves occur where? • It gets Very shallow Very fast • And or the wave bends around an obstruction Pipeline, HI

  41. Challenge Question • Could Anyone really surf Lake Tahoe? • ? • What conditions would be needed? • Sustained High Winds • Lots of Fetch • What direction? • Bathymetric Obstruction where? 1600’ • So Locate the best Possible Surf break?

  42. 11/29/2009- Powerful Winter Storm Hits Tahoe Basin • 60-100 mph Winds from South! • It Can been done! and Was!!! • Munk would be proud

  43. Applications of Wave Theory • Tsunamis • A real Serious Threat! • Warning System (when earthquake registers – Send the Alert) • Few minutes all you need – get to Higher Ground (2nd story)

  44. Applications of Wave Theory • Tsunamis • Generated by vertical displacement of seafloor • (earthquakes) • Landslides • Eruptions • Do they Have Large or Small Wavelengths? • Very Large: When reach shore, What Happens? • a Big WAVE! • Challenge Question? • If out to see in row boat earthquake/ Tsunami Hits • Could you notice a change in sea level change? • NO – b/c the very longggggg wavelength – • Small sea surface height change/time

  45. Applications of Wave Theory • Tsunamis • Generated by vertical displacement of seafloor • Creates upsurge of Water Propagates outward • Very Tall waves Exceed sea level ANIMATION / Summary http://www.youtube.com/watch?v=4Xebwzb3dDE&feature=related http://www.youtube.com/watch?v=g15sZ_d2WUY&feature=related

  46. Applications of Wave Theory – Final Thoughts • Knowing what we Know about Waves • What can we do? • Early detection of Earthquakes etc. •  Tsunami Warning System • Erosion – Next Time (Beaches/ Tides etc.) • Can we make our own surf?

  47. Applications of Wave Theory • Human Made Surf Breaks? • A potential Reality Will Bournemouth Surf Reef Ever Produce Waves? Australia JUST NEED THE RIGHT conditions -Pending . . . http://www.kqed.org/quest/television/science-of-big-waves

  48. Remember Midterm Monday – • Green Scantron • Study your notes • Have a Peaceful Weekend

  49. ROGUE waves http://www.youtube.com/watch?v=deX7R9RbmX0&NR=1 http://www.youtube.com/watch?v=ElpzfM5knYA&feature=related Tsunami Graphic http://www.youtube.com/watch?v=4Xebwzb3dDE&feature=related Tsunami CBS http://www.youtube.com/watch?v=g15sZ_d2WUY&feature=related

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