waves - characteristics, types, and energy

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© 2011 Pearson Education, Inc. Waves and Water Dynamics

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  • 1. Waves and Water Dynamics 2011 Pearson Education, Inc.

2. Chapter Overview Most waves arewind-driven. Most waves aregenerated bystorms. Waves transmitenergy across theocean surface. Tsunami arespecial fast, longwaves generatedby seismic events. 2011 Pearson Education, Inc. 3. Wave Generation Disturbing force causeswaves to form Wind blowing acrossocean surface Interface of fluids withdifferent densities Air ocean interface Ocean waves Air air interface Atmospheric waves Water water interface Internal waves 2011 Pearson Education, Inc. 4. Internal Waves Associated withpycnocline Larger than surfacewaves Caused by tides,turbidity currents,winds, ships Possible hazard forsubmarines 2011 Pearson Education, Inc. 5. Other Types of Waves Splash wave Coastallandslides,calving icebergs Seismic sea wave or tsunami Sea floormovement Tides Gravitationalattractionamong Moon,Sun, and Earth Wake Ships 2011 Pearson Education, Inc. 6. Speed of Deep Water Waves 2011 Pearson Education, Inc. 7. Energy in Ocean Waves 2011 Pearson Education, Inc. 8. Wave Movement Waves transmit energy Cyclic motion of particles in ocean Particles may move Up and down Back and forth Around and around Particles in ocean waves move in orbital paths 2011 Pearson Education, Inc. 9. Progressive Waves Progressive waves oscillate uniformly and progresswithout breaking Longitudinal Transverse Orbital 2011 Pearson Education, Inc. 10. Orbital Waves (3 types) Waves on ocean surface Anatomy Crest Trough Wave height (H) Wavelength (L) 2011 Pearson Education, Inc. 11. Orbital Wave CharacteristicsWave steepness = Height/Length If wave steepness > 1/7, wave breaks.EX:: A wave 7 meters long can only be 1 meterhigh without breaking. If the wave is any higherthan that, it will break. 2011 Pearson Education, Inc. 12. Garrett McNamara Breaks Big Wave World Record: 100 ft wave. Portugal. 13. Wave period (T) = time for one wavelength topass fixed point (The time it takes for two wavecrests to pass a given point.)Wave frequency = inverse of period or 1/T Note: Frequency is the reciprocal of the time taken to complete one cycle (the period), or 1/T.EX 2: Waves with a period of 12 seconds will have a frequency of 1/12 or0.083, which converts to 5 periods/minute. 14. Orbital Wave Characteristics Diameter of orbital motion decreases with depth of water Wave base = L Hardly any motion below wave base due to wave activity Ex: A wave that has a wavelength with 10 meters will have negligible movement at 5 meters below the still water level. 2011 Pearson Education, Inc. 15. Circular Orbital Motion Wave particles move ina circle Wave Motion 2011 Pearson Education, Inc. 16. 1. Deep-Water Waves Water depth is greater than wave base (>L) -depth is greater than wavelength Wave speed = celerity (C) C = L (Wavelength)/T (Period) 2011 Pearson Education, Inc. 17. 2. Transitional Waves Characteristics of both deep- and shallow-water waves Celerity depends on both water depth and wavelength - Wavelength is 2 to 20 that water depth. 2011 Pearson Education, Inc. 18. 3. Shallow-Water Waves Water depth is < L C (meters/sec) = 3.13 d(meters) or C (feet/sec) = 5.67 d (feet) Where d is water depth -tsunamis and tides are types of waves are examples of shallow water waves. 2011 Pearson Education, Inc. 19. Write out:Wave TypeDeep vs. Shallow Affects the oceanbottom?Wind WaveDeep Does not affect bottom(depth > wavelength)TsunamiShallowStrongly affects bottom.(depth is < ofwavelength).TidesShallowAffects bottom.