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Significant wave height H 1/3, or H s or H sig, as determined in the time domain, directly from the time series of the surface elevation, is defined as the average height of that one-third of the N measured waves having the greatest heights: [5] / = = where H m represents the individual wave heights, sorted into descending order of height as m increases from 1 to N.
The significant wave height H 1/3 — the mean wave height of the highest third of the waves. The mean wave period, T 1. In addition to the short-term wave statistics presented above, long-term sea state statistics are often given as a joint frequency table of the significant wave height and the mean wave period.
Depending on context, wave height may be defined in different ways: For a sine wave, the wave height H is twice the amplitude (i.e., the peak-to-peak amplitude): [1] =.; For a periodic wave, it is simply the difference between the maximum and minimum of the surface elevation z = η(x – c p t): [1] = {()} {()}, with c p the phase speed (or propagation speed) of the wave.
This figure represents an average height of the highest one-third of the waves in a given time period (usually chosen somewhere in the range from 20 minutes to twelve hours), or in a specific wave or storm system. The significant wave height is also the value a "trained observer" (e.g. from a ship's crew) would estimate from visual observation ...
Wave height (from trough to crest) Wave length (from crest to crest) Wave period (time interval between arrival of consecutive crests at a stationary point) Wave propagation direction; Wave length is a function of period, and of water depth for depths less than approximately half the wave length, where the wave motion is affected by friction ...
The rule states that over the first period the quantity increases by 1/12. Then in the second period by 2/12, in the third by 3/12, in the fourth by 3/12, fifth by 2/12 and at the end of the sixth period reaches its maximum with an increase of 1/12. The steps are 1:2:3:3:2:1 giving a total change of 12/12.
The equilibrium tide theory calculates the height of the tide wave of less than half a meter, while the dynamic theory explains why tides are up to 15 meters. [37] Satellite observations confirm the accuracy of the dynamic theory, and the tides worldwide are now measured to within a few centimeters.
Tide tables, sometimes called tide charts, are used for tidal prediction and show the daily times and levels of high and low tides, usually for a particular location. [1] Tide heights at intermediate times (between high and low water) can be approximated by using the rule of twelfths or more accurately calculated by using a published tidal ...