1. Waves

2. Wave Terminology

3. H = Height A = Amplitude = 1/2H L = λ = Wave Length ( distance 2 consecutive crests) T = Wave Period (Time between 2 consecutive crests) f = Wave Frequency = 1/T (# waves/sec) C = Wave Speed or Celerity = L/T (m/s) H/L = Wave Steepnes –Waves Break = H/L = 1/7

4. Wave Motion & Energy

5. Wave Spectrum

6. Ocean surface waves

7. Wind Waves What influences wave size? –Wind Speed H, L, T –Duration of wind Maximum H –Fetch Maximum H –Wave Height (H) –Wave Interference

8. i.e. Effect of wind speed on H

9. Wave Interference

10. Wave Interference – Area of Fetch

11. Fetch Area

12. Wave formation in storms Fetch Area: Chaotic (Rogue Waves)

13. Wave Speed (Deep Water) C = L/T = 1.25 * √L L = 1.56 *T 2 Slow Wave Speed –long Period (T) –Short Length (L) Fast Wave Speed –Short Period (T) –Long Length (L)

14. Wave Dispersion Outside Fetch Area: L, T & C remain constant

15. Waves and Currents

16. Reduction speed = Increase steepness C=L/T Steepness = H/L

17. Figure 9.9

18. Orbital Motion

19. Shallow Water Waves Deep Water Waves (Depth > L/2) C = L/T = 1.25 * √L Intermediate Waves (L/2 > D > L/20) C ~ D, L Shallow Water Waves (d < L/20) C = 3.13 * √D

20. Shallow Water Waves

21. Shallow Water Waves (d < L/20) C = 3.13 * √D C = L / T –C (speed) diminishes in shallow water –T (period) remains constant –.. So L (Length) must also diminish –C & L depend on depth

22. Figure 9.12

23. Shallow Water Wave Height

24. Shallow Water Waves When D<L/20 Speed decreases ~ D Length decreases ~ D Height increases ~ D Wave steepness (H/L) –Increases very quickly H/L = 1/7 Waves break

26. Wave Difraction

27. MUNDAKA VIDEO

28. Teahupoo – Tahiti surging breaker long wavelengths steep slope

29. Teahupoo Tahiti

30. Pipeline - Oahu plunging breaker

31. Folly Beach - SC plunging breaker moderate slope, small wavelength

32. Rip Currents

33. Tsunami Waves Earthquakes L ~ 100 – 200 Km P ~ 10 - 30 minutes Shallow Water Waves C over 4000m depth = 200 m/s = 720 km/h Refracted by topography Height at sea = 1-2 meters Dangerous in shallow water H~10’s m ; T~10-30 min.

34. Figure 9 p264 (figure 1)

35. Figure 9.24

37. Wave trains or ‘sets’ Train Speed = ½ wave speed = 1/C