Wave Action

1
Wave Action

• Section 13.1

2
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

3
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

4
What is a wave?

• Crest highest point
• Trough lowest point

Wavelength distance from crest to crest Wave
height distance from crest to trough
5
Wavelength
Wave height
Crest
Trough
Wave Depth is half the wavelength
6
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.
7
How waves change near shore

• Tsunamis usually caused by an earthquake
• beneath the ocean floor

8
How waves affect the shore

• Longshore Drift the movement of sand as water
  washes up and carries sand along the beach

9
How waves affect the shore

• Rip current
• - a rush of water that flows rapidly back to sea
  through a narrow opening

10
Waves and beach erosion
Groins
Barrier Beaches
Sand Dunes