Editing Tide (section)

=== Bathymetry ===
[[File:Gorey Harbour at low tide.JPG|thumb|The harbour of [[Gorey, Jersey]] falls dry at low tide.]]
The shape of the shoreline and the ocean floor changes the way that tides propagate, so there is no simple, general rule that predicts the time of high water from the Moon's position in the sky. Coastal characteristics such as underwater [[bathymetry]] and coastline shape mean that individual location characteristics affect tide forecasting; actual high water time and height may differ from model predictions due to the coastal morphology's effects on tidal flow. However, for a given location the relationship between lunar [[altitude (astronomy)|altitude]] and the time of high or low tide (the [[lunitidal interval]]) is relatively constant and predictable, as is the time of high or low tide relative to other points on the same coast. For example, the high tide at [[Norfolk, Virginia]], U.S., predictably occurs approximately two and a half hours before the Moon passes directly overhead.

Land masses and ocean basins act as barriers against water moving freely around the globe, and their varied shapes and sizes affect the size of tidal frequencies. As a result, tidal patterns vary. For example, in the U.S., the East coast has predominantly semi-diurnal tides, as do Europe's Atlantic coasts, while the West coast predominantly has mixed tides.<ref name=noaa7b>{{cite web |website=U.S. [[National Oceanic and Atmospheric Administration]] (NOAA) National Ocean Service (Education section) |url=http://oceanservice.noaa.gov/education/kits/tides/media/supp_tide07b.html |title=map showing world distribution of tide patterns, semi-diurnal, diurnal and mixed semi-diurnal |access-date=2009-09-05 |archive-date=2018-08-27 |archive-url=https://web.archive.org/web/20180827211303/http://oceanservice.noaa.gov/education/kits/tides/media/supp_tide07b.html |url-status=live }}</ref><ref>{{cite book |first=H.V. |last=Thurman |date=1994 |title=Introductory Oceanography |edition=7th |location=New York |publisher=[[Macmillan Publishers]] |pages=252–276}}ref</ref><ref>{{cite book |first=D.A. |last=Ross |date=1995 |title=Introduction to Oceanography |location=New York |publisher=[[HarperCollins]] |pages=236–242}}</ref> Human changes to the landscape can also significantly alter local tides.<ref>{{cite news |last1=Witze |first1=Alexandra |title=How humans are altering the tides of the oceans |url=https://www.bbc.com/future/article/20200703-how-humans-are-altering-the-tides-of-the-oceans |access-date=8 July 2020 |work=BBC Future |publisher=[[BBC]] |date=5 July 2020 |archive-date=6 July 2020 |archive-url=https://web.archive.org/web/20200706134113/https://www.bbc.com/future/article/20200703-how-humans-are-altering-the-tides-of-the-oceans |url-status=live }}</ref>