Ocean Motions Wave Action

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Wave Action
Section 13.1
What is a wave?
• Wave – movement of energy
through a body
• Wave size depends on:
strength of wind
length of time wind blows
distance over which wind blows
What is a wave?
• Wave molecules move
in a circular motion
• Molecules at the
surface move in a
bigger circle than those
that are deeper
• At a certain depth,
water is not affected by
the wave
What is a wave?
Crest – highest point
Trough – lowest point
Wavelength – distance from
crest to crest
Wave height – distance
from crest to trough
Wavelength
Crest
Trough
Wave Depth is
half the wavelength
Wave height
How waves change near shore
• Breakers – white capped waves that crash onto
the shore
Friction on the bottom slows the wave down.
Wave height increases and wave length decreases.
How waves change near shore
• Tsunamis – usually caused by an earthquake
beneath the ocean floor
How waves affect the shore
• Longshore Drift – the movement of sand
as water washes up and carries sand
along the beach
How waves affect the shore
• Rip current
- a rush of water
that flows rapidly
back to sea
through a narrow
opening
Waves and beach erosion
Barrier Beaches
Sand Dunes
Groins
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