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Waves for Paddlers Understanding Lake and Ocean Waves with Pictures

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Waves for Paddlers Understanding Lake and Ocean Waves with Pictures Waves for Paddlers Understanding Lake and Ocean Waves with Pictures Greg Anderson Northeastern Illinois University 2017 The Gales 2017 G. Anderson Waves for Paddlers – slide 1 / 64 By Florian K - Own work, CC BY-SA 3.0 Local Motion In A Water Wave In deep water, waves oscillate in circles. The radius decreases with depth. The Gales 2017 G. Anderson Waves for Paddlers – slide 4 / 64 Local Motion In A Water Wave In deep water, waves oscillate in circles. The radius decreases with depth. The Gales 2017 G. Anderson Waves for Paddlers – slide 4 / 64 Local Motion In A Water Wave In deep water, waves oscillate in circles. The radius decreases with depth. The Gales 2017 G. Anderson Waves for Paddlers – slide 4 / 64 Local Motion In A Water Wave In deep water, waves oscillate in circles. The radius decreases with depth. The Gales 2017 G. Anderson Waves for Paddlers – slide 4 / 64 Local Motion In A Water Wave In deep water, waves oscillate in circles. The radius decreases with depth. The Gales 2017 G. Anderson Waves for Paddlers – slide 4 / 64 Local Motion In A Water Wave In deep water, waves oscillate in circles. The radius decreases with depth. The Gales 2017 G. Anderson Waves for Paddlers – slide 4 / 64 Local Motion In A Water Wave In deep water, waves oscillate in circles. The radius decreases with depth. The Gales 2017 G. Anderson Waves for Paddlers – slide 4 / 64 Local Motion In A Water Wave In deep water, waves oscillate in circles. The radius decreases with depth. The Gales 2017 G. Anderson Waves for Paddlers – slide 4 / 64 Local Motion In A Water Wave In deep water, waves oscillate in circles. The radius decreases with depth. The Gales 2017 G. Anderson Waves for Paddlers – slide 4 / 64 The Great Wave The Wave Local Motion In A Water Wave Wavelength & Period, & Height Wavelength (λ) Wave Period (T ) Idealized Wave Spectrum Wavelength & Period, Wave Height Lake Superior Buoy 45004 (2016) & Height Wave Speed & Dispersion Reflection, Refraction & Diffraction Combining Waves Shoaling and Breaking Group Velocity Stokes Drift The Gales 2017 G. Anderson Waves for Paddlers – slide 5 / 64 Wavelength (λ) Wavelength: the distance over which a periodic wave repeats. λ Distance 1λ 2λ 3λ λ The Gales 2017 G. Anderson Waves for Paddlers – slide 6 / 64 Wave Period (T ) Period: the time interval in which a periodic wave repeats. T Time 1T 2T 3T T Wave frequency = f =1/T . The Gales 2017 G. Anderson Waves for Paddlers – slide 7 / 64 Idealized Wave Spectrum Wave Period Wavelength Cause Capillary < 0.1 s < 0.02 m local wind Chop 1–10 s 1–10 m local wind Swell 10–30 s 102 m distant storms ∼ Seiche 10 m–10 hr 102 km pressure, storm surge ∼ Tsunami 10 60 min submarine disturbance − Tide 12.4, 24.8 hr 103 km Sun, moon ∼ The Gales 2017 G. Anderson Waves for Paddlers – slide 8 / 64 Wave Height Wave height: The vertical distance from peak to trough. MWL Height H . λ/7 (deep water) H . d/1.8 (shallow water) Amplitude: One half of the Wave Height. The vertical distance from Mean Water Level (MWL) to the peak or trough. The Gales 2017 G. Anderson Waves for Paddlers – slide 9 / 64 bbbbbbbbbbbbbbbbbb Lake Superior Buoy 45004 (2016) water depth = 237 m b 5 b b b NOAA NDBC b b b b (m) b s 4 b b H b b b b b b bb b bb b b b b b bb bb b b b bbb b b b bb b bb b b bbb bb 3 b bb b b b b b b b b bbb b bb b b bbb bb bb b b b b bbb bbb b b b bb bb b bbb b bb b b bb bb b b bb b bb b b bbbbb bbbb bb bb b bb bb bbb b b b b b bb b b b bbbbbbbbb bb bbb b bb b bb bbb b b bbbb bbbbbbb b bb b bbb bbb bb b b bbb bbb b b b bbb bb b bb bb b bbbbbb bbbb bbb b bb bbbbb bbbbb bb bb bb bbbb b bb bb bbbb bbbbbbb b b 2 b bbbb b bbb b bbb bbbbb b b b bb b bbb bbb bb bb bbbb bbbb b bbbbb bb b bbb bbbbbbbb bb bbbbb bbb b bb bbb bbbb b bb bbbbbbb bbbbbb bbbb b bbbbbbbbbbb b bbb bb b bb bbbbbb bbb bb b bbb bbbb bbbbbbbb bbb bbb bb b b bb bb bbbb bbbbbbbb bbb b b bbb bbbb bbbbbbbbbb bbbbb bb bb bbbbb bbbbbbbbb bbb bbb b b bbb bb bbbbbbb bbbbbbbbb bbbbbbb bbb b bbbbb bbbbbbb bbbbbbbb bbbbbbbbb bbbb bbbb bbbbb bb bb bbbbbbb bbbbbbbb bb bb b b bbbb bbbbb 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b Significant Wave Height b b bbb bbbbbbb bbbbbbb bbb bbbbbbbbbbbb bbbbbb bbbbbbbbbbb bbbbbbb bbb bbbbbbbbb bbbbbbbbbbbbbb bbbbbbb bbbbbbbbbb bbbbbbbb bbb bbb bb bb bb bb b b b bbb bb bbb bbb bbbbbb bbb bbb bbbb b bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 0 bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb 0 1 2 3 4 5 6 7 8 9 101112 Dominant Wave Period (seconds) The Gales 2017 G. Anderson Waves for Paddlers – slide 10 / 64 The Great Wave The Wave Local Motion In A Water Wave Wavelength & Period, & Height Wave Speed & Dispersion Wave Speed Dispersion Wave Speed & Estimating Wave Speeds Wave Speeds in Deep Water Dispersion (d > λ/2) Deep vs Shallow Regimes Reflection, Refraction & Diffraction Combining Waves Shoaling and Breaking Group Velocity Stokes Drift The Gales 2017 G. Anderson Waves for Paddlers – slide 11 / 64 Wave Speed The phase velocity of the wave satisfies: λ = cT t =0 x The Gales 2017 G. Anderson Waves for Paddlers – slide 12 / 64 Wave Speed The phase velocity of the wave satisfies: λ = cT t = 1T 8 x The Gales 2017 G. Anderson Waves for Paddlers – slide 12 / 64 Wave Speed The phase velocity of the wave satisfies: λ = cT t = 2T 8 x The Gales 2017 G.
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