What Are Proxigean Tides? Learn All About These Extraordinary Tidal Ranges
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Earth experiences proxigean tides—an extraordinary tidal range that, when combined with other factors (such as unusually low barometric pressure or onshore winds), can cause erosion on coastlines, among other problems.
The proximity of the Sun to Earth in December or January will occasionally coincide with a new or full Moon that just happens to occur when the Moon is at its monthly perigee—or perhaps even when it's at the year's most extreme perigee. This potent combination happened in 1990, 1992, and 2001.
This series of events can result in interesting but not necessarily destructive ocean levels. The final devastating ingredient is a storm at sea. The onshore winds of an ocean storm can literally whip up the waters, typically raising tides by several feet and occasionally by much more. What's more, the low pressure characteristic of such storms lifts oceans: A 1-inch drop in barometric pressure raises the seas by 13.2 inches, which can cause a dangerous period of proxigean tides to boil over into a coastal catastrophe (It's also possible for only one of any given day's two high tides to be catastrophic).
Proxigean tidal conditions combined with disastrous storms to bring death and calamity to the eastern and southern United States in 1723, 1846, 1851, 1885, 1900, 1914, 1931, and 1978. The greatest loss of life—6,000 people—occurred in Galveston, Texas, on September 8, 1900. Low–lying regions of Europe also have faced devastation when such astronomical and meteorological conditions coincided: 100,000 people died in Holland in 1099, and half that many in 1287.
Rain is likely to commence on the turn of the tide.
-Weather proverb
About The Author
Bob Berman
Bob Berman, astronomer editor for The Old Farmer’s Almanac, covers everything under the Sun (and Moon)! Bob is the world’s most widely read astronomer and has written ten popular books.
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