Editing Tide (section)

=== Timing ===
[[File:Diurnal tide types map.jpg|thumb|The same tidal forcing has different results depending on many factors, including coast orientation, continental shelf margin, water body dimensions.|alt=World map showing the location of diurnal, semi-diurnal, and mixed semi-diurnal tides. The European and African west coasts are exclusively semi-diurnal, and North America's West coast is mixed semi-diurnal, but elsewhere the different patterns are highly intermixed, although a given pattern may cover {{convert|200|-|2000|km|mi}}.]]
The tidal forces due to the Moon and Sun generate very long waves which travel all around the ocean following the paths shown in [[#Phase and amplitude|co-tidal charts]]. 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. Springs and neaps in the [[North Sea]], for example, are two days behind the new/full moon and first/third quarter moon. This is called the tide's ''age''.<ref>{{cite web |url=https://glossary.ametsoc.org/wiki/Age |title=Glossary of Meteorology |website=[[American Meteorological Society]] |access-date=2021-04-02 |archive-date=2021-05-08 |archive-url=https://web.archive.org/web/20210508194219/https://glossary.ametsoc.org/wiki/Age |url-status=live }}</ref><ref>{{cite book
|title=The elements of physics |first1=Thomas |last1=Webster |publisher=Printed for Scott, Webster, and Geary |date=1837 |page=[https://archive.org/details/elementsphysics00websgoog/page/n184 168] |url=https://archive.org/details/elementsphysics00websgoog}}</ref>

The ocean [[bathymetry]] greatly influences the tide's exact time and height at a particular [[coast]]al point. There are some extreme cases; the [[Bay of Fundy]], on the east coast of Canada, is often stated to have the world's highest tides because of its shape, bathymetry, and its distance from the continental shelf edge.<ref>{{cite web |url=http://www.waterlevels.gc.ca/english/FrequentlyAskedQuestions.shtml#importantes |title=FAQ |access-date=June 23, 2007 |archive-date=February 12, 2012 |archive-url=https://web.archive.org/web/20120212231548/http://www.waterlevels.gc.ca/english/FrequentlyAskedQuestions.shtml#importantes |url-status=dead}}</ref> Measurements made in November 1998 at Burntcoat Head in the Bay of Fundy recorded a maximum range of {{convert|16.3|m|ft}} and a highest predicted extreme of {{convert|17|m|ft}}.<ref name=BIO2004>{{cite journal |last1=O'Reilly |first1=C.T.R. |first2=Ron |last2=Solvason |first3=Christian |last3=Solomon |name-list-style=amp |title=Where are the World's Largest Tides |journal=BIO Annual Report "2004 in Review" |date=2005 |pages=44–46 |editor1-first=J. |editor1-last=Ryan |publisher=Biotechnol. Ind. Org. |location=Washington, D.C.}}</ref><ref name=FundyWorkshop>{{cite book |first1=Charles T. |last1=O'reilly |first2=Ron |last2=Solvason |first3=Christian |last3=Solomon |chapter-url=http://www.bofep.org/PDFfiles/BoFEP6thProceedings.pdf |chapter=Resolving the World's largest tides |editor1-first=J.A |editor1-last=Percy |editor2-first=A.J. |editor2-last=Evans |editor3-first=P.G. |editor3-last=Wells |editor4-first=S.J. |editor4-last=Rolston |date=2005 |title=The Changing Bay of Fundy-Beyond 400 years, Proceedings of the 6th Bay of Fundy Workshop, Cornwallis, Nova Scotia, Sept. 29, 2004 to October 2, 2004. Environment Canada-Atlantic Region, Occasional Report no. 23. Dartmouth, N.S. and Sackville, N.B. |access-date=April 1, 2013 |archive-date=August 27, 2016 |archive-url=https://web.archive.org/web/20160827202033/http://www.bofep.org/PDFfiles/BoFEP6thProceedings.pdf |url-status=live }}</ref> Similar measurements made in March 2002 at Leaf Basin, [[Ungava Bay]] in northern [[Quebec]] gave similar values (allowing for measurement errors), a maximum range of {{convert|16.2|m|ft}} and a highest predicted extreme of {{convert|16.8|m|ft}}.<ref name=BIO2004 /><ref name=FundyWorkshop /> Ungava Bay and the Bay of Fundy lie similar distances from the continental shelf edge, but Ungava Bay is only free of [[pack ice]] for about four months every year while the Bay of Fundy rarely freezes.

[[Southampton]] in the United Kingdom has a double high water caused by the interaction between the ''M''<sub>2</sub> and [[Theory of tides#Short period|''M''<sub>4</sub> tidal constituents]] (Shallow water overtides of principal lunar).<ref name="Pingree_1978">{{cite journal |last1=Pingree |first1=R.D. |last2=Maddock |first2=L. |year=1978 |title=The M4 tide in the English Channel derived from a non-linear numerical model of the M2 tide |journal=Deep-Sea Research |volume=25 |pages=53–63}}</ref> [[Isle of Portland|Portland]] has double low waters for the same reason. The ''M''<sub>4</sub> tide is found all along the south coast of the United Kingdom, but its effect is most noticeable between the [[Isle of Wight]] and [[Isle of Portland|Portland]] because the ''M''<sub>2</sub> tide is lowest in this region.

Because the oscillation modes of the [[Mediterranean Sea]] and the [[Baltic Sea]] do not coincide with any significant astronomical forcing period, the largest tides are close to their narrow connections with the Atlantic Ocean. Extremely small tides also occur for the same reason in the [[Gulf of Mexico]] and [[Sea of Japan]]. Elsewhere, as along the southern coast of [[Australia]], low tides can be due to the presence of a nearby [[Amphidromic point|amphidrome]].