Unit 7 Waves

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Unit 7 Waves Beaches
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Topic 1 Watching Waves

• Surf zone is the area near shore where waves
  break.
• How far from shore a wave breaks depends on the
  length of the wave and the depth of the water.
• How a wave breaks depends on the
• steepness of the bottom slope
• whether the slope is smooth or irregular
• whether the bottom is composed of shifting sand
  or solid rock

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• Waves may break more than once as they come to
  shore.
• Each time it breaks, it gives up energy and
  becomes smaller and shorter.

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Types of Breaking Waves

• Plunging waves
• Occurs when the swell comes out of deep water and
  hits a shallow sandbar or reef.
• Form where there is a moderately steep, sloping
  bottom.
• Form tubes or curls that cascade water in a
  circular motion downward into the trough and
  break forcefully with a rapid release of energy.
• If the bottom is very steep, the top of the wave
  may break over the lower half forming a
  Collapsing wave with no curl.

• Ultimately, these are the waves that surfers look
  for.
• They break top to bottom and tend to be faster
  and more challenging.

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• Spilling breakers
• They form where the bottom slopes gradually.
• These waves advance to shore with a line of foam
  down their front.
• They break slowly over long distances
• The wave energy is gradually released over time
  and the beach.
• This type of surf is best for landing craft.

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Break slowly
Break rapidly
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• Surging breakers
• Steep beach slope
• They form when large waves suddenly hit bottom in
  shallow water.
• Wave does not break - surges up to beach
• Example Tsunami and tidal bores which look like
  walls of water advancing toward shore.

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