Are Tides Waves? Yes and it’s essential to make that point before we can understand how tides, and tidal currents, behave in coastal environments – the place where most coastal residents are likely to encounter them. By the way, the “tide waves” discussed here are in no way related to “tidal waves” or tsunamis, the comparatively rare and very destructive seismic sea waves generated by undersea earthquakes and volcanism.
Tide waves have an entirely different origin and are truly everyday events. The characteristic that easily sets them apart from wind waves and other common wave examples is their wavelength spanning thousands of nautical miles in the open ocean, giving them the name long waves. But they have other properties that identify them as well. We’ll start with the basic form of a wave as specified by its height and length.
The ratio of wave height to wavelength gives the wave steepness. Obviously tide waves are pretty darn flat since their wavelengths are never less than a hundred kilometers (a kilometer is a little more than half a nautical mile) and their heights are often less than a meter. That’s why, to an observer, tides just seem to rise and fall like water in a tub without much else to suggest a moving wave. In terms of wave dynamics and what goes on inside a wave, we must compare the dimensions of the wave to the dimensions of the sea that contains them, starting with the depth. Water depth determines whether we have a deepwater wave or a shallow water wave.
Deepwater waves – As a rule, when the water depth is greater than one-half of the wavelength, the wave is classified as a deepwater wave. Water particles inside this type of wave move forward and back, up and down in a circular orbit whose diameter decreases with depth until it essentially disappears at the wave base. With each orbit, the particles inch their way forward by a slight amount producing what is called Stokes drift. The waveform itself moves forward in the direction of wave advance at a much faster rate.
“Somewhere else! When the tide is out where you live, it is high tide at other places. The total amount of water in the oceans stays the same.
“If the Earth was entirely covered by water, the pattern would be high right under the Moon, pulled towards it by gravitational attraction which is stronger there than the average for the Earth, and also on the opposite side of the Earth where the attraction is weaker. Low tide would occur in the region between the bulges. The bulges would rotate around the Earth, following the path of the Moon and giving two high tides each day, not just one.
“The presence of land greatly complicates the patterns. Now the tides rotate around ocean basins like giant waves.
“The Sun also causes tides. At full moon and new moon, the Sun and Moon are lined up and cause big tides called 'spring tides'. At the Moon’s quarters, the Sun and Moon are tugging against each other, causing small tides called 'neap' tides.”
2007-01-05 10:23:43
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answer #1
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answered by chole_24 5
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On the Hudson River, the tide runs up the river in 8 hours and back in 5 hours. The water being kept in the river channel goes up and back. On the Chesapeake the tide runs up the bay and then down. If we get a big wind on the Chesapeake it can blow the water out to sea and we never get a high tide.
2007-01-06 10:37:00
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answer #2
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answered by science teacher 7
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To another beach on the other side of the ocean, where the tide is going in.
2007-01-05 18:18:10
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answer #3
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answered by abfabmom1 7
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I think the water just shifts from one side of the water mass to the other since it is the moons gravity that causes the shift.
2007-01-05 18:19:10
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answer #4
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answered by Don W 6
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