waves

• When waves move towards shallow water, their behavior changes, typically at a depth of half a wavelength
• At this depth, the deepest circling water molecules come into contact with the sea floor, profoundly changing the speed, direction, and shape of the waves
• In shallow water, waves slow down as they drag across the sea floor, the wavelength decreases, and successive waves start to bunch up
• The deepest part of the wave slows down more than the top, causing the wave to steepen as the crest advances ahead
• The wave eventually breaks against the shore when the water depth is less than 1.3 times the wave height
• Three types of breaking waves:

  • Spilling: steep waves breaking onto gently sloping beaches, water spills gently forward as the wave breaks
  • Plunging: moderately steep waves breaking onto steep beaches, water plunges vertically downwards as the crest curls over
  • Surging: on steep beaches, the wave slides forward and does not actually break
• A wave possesses potential energy due to its position above the wave trough and kinetic energy caused by the motion of the water within the wave
• How water moves within a wave:

  • Waves drag in shallow water approaching a headland, making the wave high, steep, and short
  • The part of the wave in deeper water moves forward faster, causing the water to bend
  • The low-energy wave spills into the bays as most of the wave energy is concentrated on the headland