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

Crest

Trough

Wavelength Wave height

Wave Depth ishalf the wavelength

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