| 词条 | Perigean spring tide |
| 释义 |
A proxigean spring tide (also known as a perigean spring tide) is a tide that occurs three or four times per year when the Moon's perigee (its closest point to Earth during its 29.5-day elliptical orbit) coincides with a spring tide (when the Earth, Sun and Moon are nearly aligned every two weeks).[1] This tide usually adds only a couple of inches to normal spring tides.[1] Astronomical causesThe Moon's orbit around Earth is elliptical, which causes the Moon to be closer to Earth and farther away at different times. The Moon and the Sun are aligned every two weeks, which results in spring tides, which are 20% higher than normal. During the period of the new moon, the Moon and Sun are on the same side of Earth, so the high tides or bulges produced independently by each reinforce each other (and has nothing to do with the spring). Tides of maximum height and depression produced during this period are known as spring tide. Spring tides that coincide with the moon's closest approach to Earth ("perigee") have been called perigean spring tides and generally increase the normal tidal range by a couple of inches.[2] The Ash Wednesday Storm of 1962 which inundated the entire Atlantic coastline of the United States from the Carolinas to Cape Cod, resulting in a loss of 40 lives and over 500 million dollars of property damage, coincided with a perigean spring tide.[3] See also
Notes1. ^1 {{cite web |url=http://oceanservice.noaa.gov/facts/perigean-spring-tide.html |title=A perigean spring tide occurs when the moon is either new or full and closest to Earth |date=July 18, 2013 |work=National Ocean Service |publisher=National Oceanic and Atmospheric Administration |accessdate=February 2, 2014}} 2. ^{{cite web |title=Tide Predictions & Data Tidal Current Predictions and Data Data Access Problems FAQ - Tide Predictions and Data |url=https://co-ops.nos.noaa.gov/faq2.html#15 |publisher=National Oceanic and Atmospheric Administration |accessdate=15 August 2018}} 3. ^{{cite web|url=http://www.gpo.gov/fdsys/pkg/CZIC-gc356-a1-w66-1978/xml/CZIC-gc356-a1-w66-1978.xml |title=The strategic role of perigean spring tides in nautical history and North American coastal flooding, 1635-1976 |publisher=Gpo.gov |date= |accessdate=2012-03-11}} References
External links
1 : Tides |
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