Waves

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WAVES
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Waves are energy moving across the ocean

• Waves can be caused by 3 things
• A. Wind (Wind-driven waves)
• B. Moons and Suns gravitational attraction
  (Tides)
• C. Earthquakes, volcanic eruptions, landslides,
  meteorites (Tsunamis / Seismic Waves)

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Wind-Driven Waves

• 2. The size of a wind driven wave is determined
  by
• a. time the wind blows
• b. the speed of the wind
• c. Fetch distance over water that the wind
  blows

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Characteristics of waves

• 3. Characteristics of waves include
• a. Crest the highest point of a wave
• b. Trough the lowest point of the wave
• c. Wavelength (?) Distance between successive
  (2) crests or successive (2) troughs
• d. wave height- distance between a crest and a
  trough

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• e. Still water line level of the water if there
  was no wind
• f. Amplitude ½ the wave height the distance
  between the crest or the trough and the still
  water line
• g. Frequency the number of waves that pass a
  particular point in a given time period
  (waves/sec)
• h. Period the time it takes for two successive
  waves to pass a particular point (sec/wave)
• i. Speed wavelength/period

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Wave Characteristics
Still-water line
Wavelength
Crest
Wave height
Amplitude
Trough
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Types of Water Waves

• Wind-driven (capillary) wave small ripples less
  than 1 tall, restoring force is surface tension
• Wind-driven (gravity) wave waves greater than
  1 tall, restoring force is gravity
• Seismic wave (tsunami) caused by earthquakes,
  volcanic eruptions, landslides, and meteorites.
  Restoring force is gravity.
• Deep water long wavelength and short amplitude
• A boat at sea may not even notice the tsunami
  underneath
• Shallow water short wavelength and high
  amplitude
• Wave height increases dramatically depending on
  shoreline topography

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• Tides extremely long wavelength, caused by
  gravitational attraction between earth, moon, and
  sun and centrifugal force (due to Earths
  rotation). Restoring force is gravity and
  Coriolis effect.

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Wave Interaction

• Constructive interference
• Occurs when the crest of waves coming from two
  directions coincide and the resulting wave crest
  is higher than either one was
• Maybe an explanation for rogue waves
• Destructive interference
• Occurs when the crest and troughs from two waves
  coincide and the resulting wave is basically
  cancelled out.

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Orbital Wave Motion

• Deep water wave water particles move in a
  circular orbit and the size of the orbit
  decreases with depth
• Little to no water movement at a depth greater
  than ½ the wavelength.

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• Shallow water wave orbitals become flattened as
  water becomes shallow and the wave feels bottom
• When water depth is less than ½ the wavelength
  the top of the wave moves forward faster than the
  bottom of the wave and it breaks

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Types of Breakers

• Spilling breakers water from the top of the
  wave spills or tumbles down the front of the wave
  
• Most waves on Miami Beach are this type
• Found when shorelines are gently sloped
• Plunging breakers is formed when the wave crest
  curls over an air pocket and collapses
• Type preferred by surfers in Hawaii and
  California
• Found in areas where the shoreline is steeply
  sloped
• Surging breakers formed when the shoreline is
  more like a wall that rises out of the water and
  so the wave is not slowed down but surges into
  shore (can be very destructive)