Ch. 11 Waves

What is a wave?

A periodic, vertical displacement of a surface caused by a generating force and restored by a restoring force.

What are the two primary forces acting on ocean waves?

• Generating force: Causes the wave (e.g., wind, seismic activity).

• Restoring force: Brings the wave back to equilibrium (e.g., gravity, surface tension).

What are capillary waves, and what forces act on them?

Small ripples caused by wind, with surface tension as the restoring force.

What are wind waves and sea swell?

Waves generated by wind, with Earth's gravity as the restoring force.

How are tsunamis generated?

By vertical movement of the seafloor, such as during an underwater earthquake.

What is the main generating force for tides?

The gravitational pull of the moon and sun.

Define crest and trough.

• Crest: Highest point of a wave.

• Trough: Lowest point of a wave.

What is wave height?

The vertical distance between the crest and the trough.

What is wavelength?

The horizontal distance between two consecutive crests or troughs.

What is wave period (T)?

The time it takes for two successive crests to pass a fixed point.

What determines wave speed in deep water?

Formula: v = 1.56T (m/s), where T is the wave period.

What is wave dispersion?

The sorting of waves by wavelength and speed as they move away from their source.

What is swell?

Long-period waves that have traveled far from their point of origin, losing energy slowly.

What happens when waves reinforce each other?

Their crests and troughs align, increasing wave height (constructive interference).

What happens when waves damp each other?

The crest of one wave coincides with the trough of another, reducing wave height (destructive interference).

How do shallow water waves change near shore?

Wave speed decreases, wavelength shortens, and wave height increases.

What causes waves to break?

When wave steepness exceeds 1/7, the crest collapses.

How does wave refraction affect coastal areas?

Waves bend as they slow down over shallow regions, concentrating energy on headlands.

What are internal waves, and where do they form?

Waves that occur along density boundaries (pycnoclines) within the ocean.

What three factors determine wave size in a storm?

Wind speed, wind duration, and fetch (distance wind blows over water).