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Wave Action

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Groin. Things to Ponder.... What are the main parts of a wave? How do waves form? ... Humans help by building groins or jetties, which are walls that prevent ... – PowerPoint PPT presentation

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Title: Wave Action


1
Wave Action
  • Chapter 13
  • Section 1

2
Key Terms
  • Wave
  • Wavelength
  • Frequency
  • Wave Height
  • Tsunami
  • Longshore Drift
  • Rip Current
  • Groin

3
Things to Ponder.
  • What are the main parts of a wave?
  • How do waves form?
  • How do waves change near the shore?

4
What Is a Wave?
  • Wave movement of energy through a body of water
  • Wave development USUALLY begins with wind.
    Otherwise, the ocean would be smooth.
  • What else could start a wave?
  • Tsunamis
  • Animals

5
Wave Size
  • Depends on three factors
  • Strength of the wind
  • Length of time the wind blows
  • Distance over which the wind blows
  • What would produce the largest waves?
  • Strong wind, blowing for a long time, over a long
    distance.

6
Wave Energy
  • In the OPEN OCEAN, water does not move. Only the
    energy of the wave moves
  • Floating objects will move in a circular motion
    and return to the starting point.
  • The further down you go, the less the waves
    affect the water.
  • Once a certain depth is achieved, waves no longer
    affect the water and its contents.

7
Parts of a Wave
Crest
Wavelength
Wave Height
Trough
  • Crest top of wave Trough bottom of wave
  • Wavelength Horizontal distance between crests
    or troughs
  • Wave Height Vertical distance from crest to
    trough
  • Frequency number of times a wave crest passes a
    point in a certain amount of time.

8
How Waves Change Near Shore
  • White-capped waves that crash onto shore are
    called breakers
  • Open ocean waves are called swells.
  • As they approach the shore, friction occurs
    between the water and the land, which causes the
    waves to slow down
  • This causes wave height to increase and
    wavelength to decrease
  • Creates a traffic jam of water and forces waves
    to break. (Diagram on board)

9
How Waves Change Near Shore
10
Tsunamis
  • Caused by an earthquake beneath the ocean
  • Sends a pulse of energy through the water
  • Due to water depth, the wave is very small as a
    swell at sea. As it approaches the land, it
    rises to incredible heights due to shallow water.

11
How Waves Affect the Shore
  • Longshore Drift as waves hit the shore at an
    angle, it carries the grains of sand down the
    beach.
  • Rip Currents a rush of water that flows rapidly
    back to sea through a narrow opening, usually
    between sand bars.
  • How do you escape a rip current if you are
    swimming and get trapped?

12
How Do We Prevent Beach Erosion?
  • Nature protects by creating barrier beaches and
    sand dunes to slow down the erosion process
  • Humans help by building groins or jetties, which
    are walls that prevent longshore drift from
    occurring.

13
Things to Ponder.
  • What are the main parts of a wave?
  • Crest, trough, wavelength, wave height
  • How do waves form?
  • Primarily wind, also tsunamis, animals, etc.
  • How do waves change near the shore?
  • Wavelength decreases and wave height increases
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