1. Sea and Swell Sea or sea area where wind-driven waves aregenerated Swell uniform,symmetricalwavesoriginating fromsea area 2011 Pearson Education, Inc.

2. Factors Affecting Wave Energy Wind speed Wind duration Fetch distance over which wind blows 2011 Pearson Education, Inc. 3. Wave Height Directly related to waveenergy Wave heights usually lessthan 2 meters (6.6 feet) Breakers called whitecapsform when wave reachescritical steepness Beaufort Wind Scaledescribes appearance of seasurface 2011 Pearson Education, Inc. 4. Global Wave Heights 2011 Pearson Education, Inc. 5. Beaufort Wind Scale 2011 Pearson Education, Inc. 6. Maximum Wave Height USS Ramapo (1933): 152-meters (500 feet) long shipcaught in Pacific typhoon Waves 34 meters (112 feet) high 2011 Pearson Education, Inc. 7. Wave Energy Fully developed sea Maximum wave height, wavelength for particular fetch, speed, and duration of winds at equilibrium conditions Swell Uniform, symmetrical waves that travel outward from storm area Long crests Transport energy long distances 2011 Pearson Education, Inc. 8. Swells Longer wavelength waves travel faster and outdistance other waves Wave train a group of waves with similarcharacteristics Wave dispersion sorting of waves by wavelengths Wave train speed is speed of individual wave 2011 Pearson Education, Inc. 9. Wave Train Movement 2011 Pearson Education, Inc. 10. Waves in Surf Zone Surf zone zone of breaking waves near shore Shoaling water water becoming gradually moreshallow When deep water waves encounter shoaling water lessthan their wavelength, they become transitionalwaves. 2011 Pearson Education, Inc. 11. Waves Approaching Shore As a deep-water wave becomes a shallow-water wave: Wave speed decreases Wavelength decreases Wave height increases Wave steepness (height/wavelength) increases When steepness > 1/7, wave breaks 2011 Pearson Education, Inc. 12. Waves Approaching Shore 2011 Pearson Education, Inc. 13. Three Types of Breakers Spilling Plunging Surging 2011 Pearson Education, Inc. 14. Spilling Breakers Gently sloping seafloor Wave energy expendedover longer distance Water slides downfront slope of wave 2011 Pearson Education, Inc. 15. Plunging Breakers Moderately steep seafloor Wave energy expendedover shorter distance Best for board surfers Curling wave crest 2011 Pearson Education, Inc. 16. Surging Breakers Steepest sea floor Energy spread overshortest distance Best for body surfing Waves break on theshore 2011 Pearson Education, Inc. 17. Surfing Like riding a gravity-operated water sled Balance of gravity and buoyancy Skilled surfers position board on wave front Can achieve speeds up to 40 km/hour (25 miles/hour) 2011 Pearson Education, Inc. 18. Wave Refraction Waves rarely approach shore at a perfect 90 degreeangle. As waves approach shore, they bend so wave crests arenearly parallel to shore. 2011 Pearson Education, Inc. 19. Wave Refraction 2011 Pearson Education, Inc. 20. Wave Refraction Gradually erodesheadlands Sediment accumulatesin bays 2011 Pearson Education, Inc. 21. Wave Reflection Waves and wave energybounced back frombarrier Reflected wave caninterfere with nextincoming wave With constructiveinterference, can createdangerous plungingbreakers 2011 Pearson Education, Inc. 22. Standing Waves Two waves with same wavelength moving inopposite directions Water particles move vertically and horizontally Water sloshes back and forth 2011 Pearson Education, Inc. 23. Tsunami Seismic sea waves Originate from sudden sea floor topography changes Earthquakes most commoncause Underwater landslides Underwater volcano collapse Underwater volcanic eruption Meteorite impact splashwaves 2011 Pearson Education, Inc. 24. Tsunami Characteristics Long wavelengths (> 200 km or 125 miles) Behaves as a shallow-water wave 2011 Pearson Education, Inc. 25. Tsunami 2011 Pearson Education, Inc. 26. Tsunami Destruction Sea level can rise up to 40 meters (131 feet) when a tsunami reaches shore. 2011 Pearson Education, Inc. 27. Tsunami Most occur in Pacific Ocean More earthquakes andvolcanic eruptions Damaging to coastalareas Loss of human lives 2011 Pearson Education, Inc. 28. Historical Tsunami Krakatau 1883 Indonesian volcanic eruption Scotch Cap, Alaska/Hilo, Hawaii 1946 Magnitude 7.3 earthquake in Aleutian Trench Papua New Guinea 1998 Pacific Ring of Fire magnitude 7.1 earthquake Indian Ocean 2004 Magnitude 9.3 earthquake off coast of Sumatra Japan 2011 Magnitude 9.0 earthquake off coast of Japan 2011 Pearson Education, Inc. 29. Historical LargeTsunami 2011 Pearson Education, Inc. 30. Banda Aceh Before FloodingImagery collected June 23, 2004 31. Banda Aceh FloodingImagery collected December 28, 2004 32. Tsunami Satellite Picture -Before & After - BandaAceh Shore 33. Banda Aceh Grand Mosque (Before Tsunami)Imagery collected June 23, 2004 34. Banda Aceh Grand MosqueImagery collected December 28, 2004 35. Banda Aceh Detail Before DebrisImagery collected June 23, 2004 36. Banda Aceh Debris DetailImagery collected December 28, 2004 37. March 11, 2011