| 词条 | Ice circle |
| 释义 |
Ice discs, ice circles, ice pans, or ice crepes are a natural phenomenon that occur in slow moving water in cold climates. They are thin circular slabs of ice that rotate slowly on a body of water's surface. TypesIce discsIce discs form on the outer bends in a river where the accelerating water creates a force called 'rotational shear', which breaks off a chunk of ice and twists it around.[1] As the disc rotates, it grinds against surrounding ice — smoothing into a circle.[2] A relatively uncommon phenomenon, one of the earliest recordings is of a slowly revolving disc spotted on the Mianus River and reported in an 1895 edition of Scientific American.[2][3] Ice pansRiver specialist and geography professor Joe Desloges states that ice pans are "surface slabs of ice that form in the center of a lake or creek, instead of along the water’s edge". As water cools, ice crystals form into 'frazil ice' and can cluster together into a pan-shaped formation.[4] If an ice pan accumulates enough frazil ice and the current remains slow, the pan may transform into a 'hanging dam', a heavy block of ice with high ridges and a low centre.[5] FormationConditionsIt is believed that ice circles form in eddy currents.[6] It has been shown that existing ice discs can maintain their rotation due to melting.[7] Artificial ice circles have also been created by cutting a large circle in a sheet of ice, such as an [https://gregcookland.com/wonderland/2018/04/21/mainers-create-worlds-largest-so-they-say-ice-merry-go-round/ "ice carousel"] constructed in Maine.[8] PhysicsIce circles tend to rotate even when they form in water that is not moving. The ice circle lowers the temperature of the water around it, which causes the water to become denser than the slightly warmer water around it. The dense water then sinks and creates its own circular motion, causing the ice circle to rotate.[9] SizeAn unusual natural phenomenon, ice disks occur in slowly moving water in cold climates and can vary in size, with circles more than 15 metres (49 ft) in diameter observed.[10][11][12][13] Ice Circle of Vana-Vigala in Estonia is reported to have had a diameter of over 20 meters,[14] whilst one approximately 298 feet (91 meters) in diameter appeared in Westbrook, Maine in January 2019.[15] Notable ExamplesIce discs have most frequently been observed in Scandinavia and North America. An ice disc was observed in Wales in December 2008 and another one in England in January 2009.[16][17][18] An ice disc was observed on the Sheyenne River in North Dakota in December 2013. An ice circle of approximately {{cvt|50|ft|m|order=flip}} in diameter was observed and photographed in Lake Katrine, New York on the Esopus Creek around January 23, 2014. In Idaho, extreme weather led to a rare sighting of an ice disc on the Snake River on January 22, 2014. On January 14, 2019, an ice disc approximately 298 feet (91 metres) wide on the Presumpscot River in Westbrook, Maine, United States drew wide media attention.[19][20][21] A smaller disc was reported by park rangers in Baxter State Park, in northern Maine, the same month.[22] See also{{commonscat|ice circles}}
References1. ^{{cite news|url=http://www.burlingtonfreepress.com/article/20100207/MULTIMEDIA/100207016/-1/multimedia/VIDEO-Moscow-Ice-Disk-a-rarity-of-nature|archive-url=https://archive.is/20120730041121/http://www.burlingtonfreepress.com/article/20100207/MULTIMEDIA/100207016/-1/multimedia/VIDEO-Moscow-Ice-Disk-a-rarity-of-nature|dead-url=yes|archive-date=July 30, 2012|title=VIDEO: Moscow Ice Disk a rarity of nature|date=February 7, 2010|accessdate=19 February 2010|work=Burlington FreePress.com|author=Patrick Garrity}} 2. ^{{Cite journal|title=A revolving ice cake|first=J. M.|last=Bates|journal=Scientific American|date=9 February 1895|volume=72|issue=6|page=86|url=https://archive.org/stream/scientific-american-1895-02-09/scientific-american-v72-n06-1895-02-09#page/n3/mode/2up/search/ice|accessdate=30 November 2013}} 3. ^Rickard, B et al: Unexplained Phenomena, page 190. Rough Guides, 2000. 4. ^{{Cite web|url=http://www.neowin.net/forum/index.php?s=4747fd3679bd6a0a01d32673bb95197f&showtopic=718912&pid=590397974&st=0&#entry590397974|title=Perfect "Ice Circle" Forms near Toronto, Canada|accessdate=14 January 2009|website=|publisher=|date=|author=Joe Desloges}} cited in: {{cite news |url=http://network.nationalpost.com/np/blogs/toronto/archive/2008/12/18/man-stumbles-on-round-spinning-creek-circle.aspx |title=Man stumbles on round, spinning ‘creek circle’ |date=18 December 2008 |first1=Kate |last1=Scroggins |first2=Rob |last2=Roberts |publisher=National Post |work=Posted Toronto |access-date=29 October 2010 |archive-url=https://web.archive.org/web/20100906111204/http://network.nationalpost.com/np/blogs/toronto/archive/2008/12/18/man-stumbles-on-round-spinning-creek-circle.aspx |archive-date=6 September 2010 |dead-url=yes |df=dmy-all }} 5. ^{{Cite web |url=http://www.neowin.net/forum/index.php?s=4747fd3679bd6a0a01d32673bb95197f&showtopic=718912&pid=590397974&st=0&#entry590397974|title= Perfect "Ice Circle" Forms near Toronto, Canada |accessdate=14 January 2009 |website= |publisher= |date= |author=Joe Desloges}} 6. ^{{Cite web|url=http://modernnotion.com/crop-circles-ice-ice-circles-form/|title=Crop Circles in the Ice: How Do Ice Circles Form?|date=2015-12-22|website=Modern Notion|language=en-US|access-date=2019-01-16}} 7. ^{{cite journal|last1=Dorbolo|first1=S|last2=Adami|first2=N.|last3=Dubois|first3=C.|last4=Caps|first4=H.|last5=Vandewalle|first5=N.|last6=Barbois-Texier|first6=B.|title=Rotation of melting ice disks due to melt fluid flow|journal=Phys. Rev. E|volume=93|pages=1–5|doi=10.1103/PhysRevE.93.03311|doi-broken-date=2019-02-22}} 8. ^{{cite web |last1=Cook |first1=Greg |title=Mainers Create World’s Largest (So They Say) Ice Merry-Go-Round |url=https://gregcookland.com/wonderland/2018/04/21/mainers-create-worlds-largest-so-they-say-ice-merry-go-round/ |website=Wonderland}} 9. ^{{cite web |last1=MacFarlane |first1=Drew |title="Maine River's Massive Disk of Spinning Ice a Sight to Behold" |url=https://weather.com/news/news/2019-01-16-spinning-ice-disk-westbrook-maine |website=The Weather Channel |accessdate=March 18, 2019}} 10. ^{{cite web|url=http://my.news.yahoo.com/video/rare-sighting-ice-disk-idaho-104748782.html|title=Rare Sighting of an Ice Disk in Idaho|author=Daniel Ostler|website=news.yahoo.com|archive-url=https://web.archive.org/web/20140202135721/http://my.news.yahoo.com/video/rare-sighting-ice-disk-idaho-104748782.html|archive-date=2 February 2014}} 11. ^{{Cite web|url=https://www.recordonline.com/article/20140123/news/140129847|title=Giant ice circle spinning in Esopus Creek|website=recordonline.com|language=en|access-date=2019-01-16}} 12. ^Blake Nicholson, Unusual ice circle forms in North Dakota river, November 26, 2013, Associated Press 13. ^Pete Thomas, Giant spinning ice circle discovered in North Dakota’s Sheyenne River, November 26, 2013, GrindTV 14. ^Jaan Viska: Jääratas pöörlemas Vana-Vigalas – mitte ainult kylauudis.ee, 11. jaanuar 2017 15. ^{{Cite web|url=https://www.bbc.co.uk/news/world-us-canada-46891412|title=Massive spinning ice disc forms in US river|website=BBC News|language=en|access-date=2019-01-16}} 16. ^{{cite news|url=http://www.timesonline.co.uk/tol/news/weather/article5511931.ece|title=Ice disc brings touch of Scandinavia to Devon river|date=14 January 2009|publisher=The Times|work=Times Online|accessdate=22 April 2010}} 17. ^1 {{cite news|url=http://www.dailymail.co.uk/news/article-1114071/Ice-Walker-discovers-10ft-wide-spinning-frozen-circle-British-waters-time.html|title=Ice one! Walker discovers 10 ft-wide, spinning frozen circle in British waters for the first time|date=13 January 2009|work=Mail Online|publisher=Daily Mail|accessdate=2009-01-13|author=David Derbyshire}} 18. ^{{cite news|url=https://www.telegraph.co.uk/earth/4227030/Spinning-ice-disc-phenomenon-seen-in-British-river-for-first-time.html|title=Spinning ice disc phenomenon seen in British river for first time|date=13 January 2009|accessdate=22 April 2010|work=Telegraph.co.uk|publisher=Telegraph Media Group Limited}} 19. ^{{cite news |title=Ice disk mania draws crowds, boosts business in Westbrook |url=https://www.wmtw.com/article/ice-disk-mania-draws-crowds-to-westbrook/25929213 |accessdate=19 January 2019 |publisher=WMTW ABC News |date=19 January 2019}} 20. ^{{Cite web|url= https://www.bbc.co.uk/news/world-us-canada-46891412|title= Massive spinning ice disc forms in US river|website=BBC News|language=en|access-date=2019-01-16}} 21. ^{{Cite web|url=https://bangordailynews.com/2019/01/15/news/portland/onlookers-share-theories-find-meaning-in-giant-maine-ice-disc/|title=Onlookers share theories, find meaning in giant Maine ice disc|website=Bangor Daily News|language=en-US|access-date=2019-01-16}} 22. ^{{cite news |title=Westbrook isn't the only place in Maine with an ice disk |url=https://www.wmtw.com/article/westbrook-isnt-the-only-place-in-maine-with-an-ice-disk/25954363 |accessdate=19 January 2019 |agency=Associated Press |publisher=WMTW ABC News |date=18 January 2019 |location=Millinocket, Maine |quote=Officials at Baxter State Park in northern Maine shared a photo of an ice disk that's about 30 or 40 feet wide, located in wilderness more than 200 miles north of much larger disk that formed in Westbrook.}} Further reading
External links
5 : Bodies of ice|Water ice|River morphology|Vortices|Circles |
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