Ocean Waves

Surface waves are caused by prevailing winds

Deep Ocean Currents are based almost entirely on density.

Waves are defined by four things.

1. Wave height

2. Amplitude

3. Wavelength

4. Crest

5. Trough

As waves move, only the energy goes in the direction of the wave. The water itself goes up and down, or perhaps round and round.

As waves come to shore, they become shorter and higher, but the energy is not reduced. Energy is expended on the shoreline, with destructive effects.

Breaker

Rip Currents, are not to be played with. They form when water returning to the ocean is funneled through a channel in an underwater sand bar, or something.

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Recognize a rip current:

Murky water from sediments stirred up by the current.

Different waves--larger and choppier.

Foam or objects that move steadily offshore.

Survive a rip current:

Don't fight the current.

Swim parallel to the shore to get out of the current.

Rip currents are rarely more than 30 feet wide.

If you can't escape, float calmly until the current dissipates then swim diagonally back to the shore.

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Tsunami ~ a wave usually caused by an underwater earthquake, or a HUGE landslide.

1. Wavelength can be 200 miles long in ocean

2. Waveheight may be only 3 feet high.

3. Boat would not even notice it.

4. Means “Harbor Wave”

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“According to a Japanese folktale, a venerable grandfather who owned a rice field at the top of a hill felt the sharp jolt of an Earth tremor one day just before the harvest. From his hilltop vantage point, he saw the sea pull back from the shore. Curious villagers rushed out to explore the exposed tidal flats and collect shellfish. From experience, the old man knew of the grave danger to his neighbors. With his grandson by his side, he dashed about his fields, setting fire to his crop. The villagers saw the smoke, and hurried up the hill to aid their neighbor. As they beat out the flames, they saw the old man scurrying ahead, setting new fires near the hill ﾕ s crest. Hoping to prevent him from destroying all of his crops, they rushed up the hill to stop him. Moments later, the villagers saw a tremendous wall of water surging onshore, flooding the flats where they had just been standing and they understood that the old man had sacrificed his harvest to save their lives.”