5 Waves and Tides Free Online FlashCards

What generates most ocean surface waves?

Wind transfers energy to the water, generating most ocean surface waves.

What three factors chiefly determine wind-generated wave size?

Wave size depends chiefly on wind speed, how long the wind blows, and fetch—the distance it travels over open water in one direction.

How is wave height measured?

Wave height is the vertical distance from the trough to the crest.

What does a wave's period measure?

Wave period is the time between successive crests passing a fixed point.

How do water particles move in ordinary surface waves?

In ordinary surface waves, water particles mostly move in small circular or elliptical paths; the wave carries energy forward.

What is swell?

Swell consists of waves that have traveled away from the area where the wind created them; they can arrive after local winds weaken.

What is wave refraction near a coast?

Refraction is a change in wave direction. Near shore, waves slow in shallow water, and their crests often bend to align more nearly with the shoreline.

What happens when a wave breaks?

As waves steepen and become unstable, they break and release energy in the surf zone.

How does longshore drift transport sand?

Waves approaching at an angle can drive a longshore current parallel to shore. This current transports sand along the coast, a process called longshore drift.

What mainly causes tides?

Tides are regular, long-period changes in sea level caused mainly by the Moon's gravitational pull, with a smaller contribution from the Sun.

How do flood and ebb currents differ?

A flood current flows in as water rises toward high tide; an ebb current flows out as water falls toward low tide.

What is slack water?

Slack water is the interval when the tide turns between rising and falling.