Waves

Classifying Waves

Waves are classified according to type of force that disturbs the water to make the wave

Wind Waves

• Wave progresses as the water moves in a circular path

Orbital Motion of Wind Waves

• Water moves in orbits
• Orbits get smaller the deeper you go.
• At a depth equal to ½ the wavelength, there is no more water motion or the wave base.

Deep Water vs. Shallow Water Waves

• Deep-water wave – when a wave is traveling in water deeper than ½ its wavelength.
• Speed is controlled by it’s wavelength. Longer waves are faster.

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• Shallow-water wave- When a wave is traveling in water shallower than ½ its wavelength.
• Speed is controlled by water depth
• Friction with the bottom slows down the wave and flattens the orbit.

Variables Controlling Wind-Wave Energy

• Wind velocity – wind must be moving faster than the wave for energy transfer to continue.
• Wind duration – Winds that blow for a short time will not generate large waves
• Fetch – Uninterrupted distance over which wind blows without changing direction. Longer fetch = larger waves.

Variables Controlling Wind-Wave Energy

Internal Waves

• Waves that occur at the boundaries of water layers of different densities.

Surf and Breaking Waves

• In deep water waves break when their height to wavelength ratio exceeds one to seven = H:L ratio exceeds 1:7

• Very destructive
• Wave does not break, but rolls onto beach

• Wave curls and forms a tunnel
• Expert surfers love these (totally tubular) or (pipe dreams)

• Gentlest of wave interactions
• Easiest to learn to surf on

Surf

• Plunging Breakers – characterized by a curl as the top of the wave pitches through the air before splashing into the bottom…Beaches with a steep incline

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• Spilling Breakers – characterized by the top of the wave tumbling and sliding down the front of the wave as it decelerates slowly.—Beaches with a gentle slope

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• Surging Breakers – on very steep beaches that are almost like walls