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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 ...
Tide tables give the height of the tide above a chart datum making it feasible to calculate the depth of water at a given point and at a given time by adding the charted depth to the height of the tide. One may calculate whether an area that dries is under water by subtracting the drying height from the [given] height calculated from the tide ...
The second strongest tidal constituent "S 2" is influenced by the sun, and its Doodson numbers are 273.555, meaning that its frequency is composed of twice the first Doodson argument, +2 times the second, -2 times the third, and zero times each of the other three. [50] This aggregates to the angular equivalent of mean solar time +12 hours.
Graph showing relationships between the rule of twelfths (coloured bars), a sine wave (dashed blue curve) and a clockface, if high tide occurs at 12:00. The rule of twelfths is an approximation to a sine curve. It can be used as a rule of thumb for estimating a changing quantity where both the quantity and the steps are easily divisible by 12 ...
Eigenvalue ε of wave modes of zonal wave number s = 1 vs. normalized frequency ν = ω/Ω where Ω = 7.27 × 10 −5 s −1 is the angular frequency of one solar day. Waves with positive (negative) frequencies propagate to the east (west).
The time when the crest of the wave reaches a port then gives the time of high water at the port. The time taken for the wave to travel around the ocean also means that there is a delay between the phases of the Moon and their effect on the tide.
The 16th-century church clock at Arnemuiden indicates the time of local high tide as a pointer on a 12-hour clockface. Maassluis. Jacob Venker's tide clock on the exterior of the Nationaal Sleepvaart Museum was installed in 1996. Despite the clock's traditional dial, it is computer-controlled, and accounts for 94 waves in its tidal timekeeping.
The first tide predicting machine (TPM) was built in 1872 by the Légé Engineering Company. [11] A model of it was exhibited at the British Association meeting in 1873 [12] (for computing 8 tidal components), followed in 1875-76 by a machine on a slightly larger scale (for computing 10 tidal components), was designed by Sir William Thomson (who later became Lord Kelvin). [13]