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Ch 16.2 Waves and Tides

Objectives:

From where do waves obtain their energy

  • Waves are energy traveling along the boundary between ocean and atmosphere.
  • Most ocean waves obtain their energy and motion from the wind.

What three factors affect the characteristics of a wave?

  1. Wind speed
  2. Length of time (duration) the wind has blown
  3. Fetch or the distance that the wind has traveled across the water.

How does energy move through a wave?

As a wave travels, the water particles pass the energy long by moving in a circle. This movement is called circular orbital motion

Circular orbital motion allows energy to move forward through the water while the individual water particles that transmit the wave move around in a circle.

Know diagram page 456

What causes “breaking waves”?

  • Breaking waves occur when the ocean bottom is less than one half the wave length and the wave begins to “feel the bottom”
  • This slows down the bottom of the wave, decreasing the wavelength and increasing the wave height.
  • When the wave is too steep to support itself and the wave front collapses or “breaks” causing water to advance up the shore.

Turbulent water created by breaking waves is called surf… but since we live in Nebraska we don’t actually get to experience the cool stuff like surf.

Know diagram page 457
At what depth do the characteristics of a wave begin to change as it approaches shore

At a water depth equal to half of the wave’s wavelength

What causes tides?