1. Waves n Characteristics of All Wind-generated Waves n Deep Water Waves n Shallow Water Waves n Other Water Waves

2. Parts of Waves Crest and Trough Crest and Trough Wavelength (L) Wavelength (L) Wave Height (H) Wave Height (H) depends on wind speed, open distance (fetch), wind duration Period (T) Period (T)

3. Motion of Water Molecules Circular motion to depth equal to one half of the wavelength

4. Deep Water Waves Water depth > one-half wavelength Water depth > one-half wavelength All wind-generated waves in open ocean, but many other waves, too All wind-generated waves in open ocean, but many other waves, too

5. Deep Water Waves (cont.) SEA : within storm regions SEA : within storm regions –Choppy/Chaotic surface –Contrast with SWELL

6. Deep Water Waves (cont.) SWELL: outside of storm regions SWELL: outside of storm regions –Smooth shape –Sorted by wavelength

8. Waves Shallow Water Waves Waves in water depth less than 1/20 of wavelength Waves in water depth less than 1/20 of wavelength Often associated with surf zone Often associated with surf zone

10. Shallow Water Waves (cont) Varieties of Surf: Consider slope of ocean floor Plunging Plunging Spilling Spilling

11. spilling plunging surging

12. Wave Speed (L/T) Deep Water Deep Water –Speed = 1.56T –T= period or time between two successive crests

13. Wave Speed (L/T) Shallow water wave speed = Shallow water wave speed = 3.1 x square root Depth

14. Wave Refraction Bending of wave crests Bending of wave crests Waves approach beach at angle Waves approach beach at angle One part of crest reaches shallow water first and slows down One part of crest reaches shallow water first and slows down Waves become more parallel to shore Waves become more parallel to shore Drawing of beach…..

15. Wave Refraction

16. Refraction along irregular coast note distribution of wave energy note distribution of wave energy most of energy strikes headlands most of energy strikes headlands causes erosion of headland, deposition in bays causes erosion of headland, deposition in bays coastal straightening occurs coastal straightening occurs

18. Other Ocean Waves Tsunamis Tsunamis

19. Tsunamis Seismic sea waves ( tidal waves) Seismic sea waves ( tidal waves) disturbance of ocean floor disturbance of ocean floor –volcanic eruption –certain earthquakes –landslides

20. Tsunamis (cont) speed greater than 700 km/hr speed greater than 700 km/hr wavelength greater than 200 km wavelength greater than 200 km crests can exceed 30 m as reach shore crests can exceed 30 m as reach shore

23. Information on tsunamis http://nctr.pmel.noaa.gov/ http://nctr.pmel.noaa.gov/ http://nctr.pmel.noaa.gov/