Editing Cyclone (section)

{{Short description|Large scale rotating air mass}}
{{About|the meteorological phenomenon}}
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[[File:Low pressure system over Iceland.jpg|thumb|upright=1.3|An extratropical cyclone near Iceland]]
{{Weather}}

In [[meteorology]], a '''cyclone''' ({{IPAc-en|ˈ|s|aɪ|.|k|l|oʊ|n}})  is a large [[air mass]] that rotates around a strong center of low [[atmospheric pressure]], counterclockwise in the [[Northern Hemisphere]] and clockwise in the [[Southern Hemisphere]] as viewed from above (opposite to an [[anticyclone]]).<ref name="AMSCcDef">{{cite web|title = Cyclonic circulation|author = Glossary of Meteorology|date = June 2000|publisher = [[American Meteorological Society]]|url = http://glossary.ametsoc.org/wiki/Cyclonic_circulation|access-date = 2008-09-17|archive-date = 2018-12-25|archive-url = https://web.archive.org/web/20181225164334/http://glossary.ametsoc.org/wiki/Cyclonic_circulation|url-status = live}}</ref><ref name="AMSCycDef">{{cite web|title = Cyclone|date = June 2000|author = Glossary of Meteorology|publisher = [[American Meteorological Society]]|url = http://glossary.ametsoc.org/wiki/Cyclone|access-date = 2008-09-17|archive-date = 2018-12-25|archive-url = https://web.archive.org/web/20181225164340/http://glossary.ametsoc.org/wiki/Cyclone|url-status = live}}</ref> Cyclones are characterized by inward-spiraling winds that rotate about a zone of [[low pressure]].<ref name="BBCCycDef">{{cite web |author = BBC Weather Glossary |title = Cyclone|date= July 2006|publisher= [[BBC]]|url = http://www.bbc.co.uk/weather/weatherwise/glossary/c.shtml|access-date = 2006-10-24|archive-url = https://web.archive.org/web/20060829214837/http://www.bbc.co.uk/weather/weatherwise/glossary/c.shtml |archive-date = 2006-08-29}}</ref><ref name="UCARCycDef">{{cite web |title = UCAR Glossary&nbsp;— Cyclone |publisher = University Corporation for Atmospheric Research |url = http://meted.ucar.edu/satmet/goeschan/glossary.htm#c |access-date = 2006-10-24 |archive-date = 2018-12-25 |archive-url = https://web.archive.org/web/20181225164339/https://www.meted.ucar.edu/sign_in.php?go_back_to=%2Fsatmet%2Fgoeschan%2Fglossary.htm#c |url-status = live }}</ref> The largest low-pressure systems are [[polar vortices]] and [[extratropical cyclone]]s of the largest scale (the [[synoptic scale]]). Warm-core cyclones such as [[tropical cyclone]]s and [[subtropical cyclone]]s also lie within the synoptic scale.<ref>National Hurricane Center (2012). [http://www.nhc.noaa.gov/aboutgloss.shtml Glossary of NHC terms.] {{Webarchive|url=https://web.archive.org/web/20120927232946/http://www.nhc.noaa.gov/aboutgloss.shtml |date=2012-09-27 }} Retrieved on 2012-08-13.</ref> [[Mesocyclone]]s, [[tornado]]es, and [[dust devil]]s lie within the smaller [[mesoscale meteorology|mesoscale]].<ref>{{cite journal|author=I. Orlanski|year=1975|title=A rational subdivision of scales for atmospheric processes|journal=Bulletin of the American Meteorological Society|volume=56|pages=527–530|issue=5|bibcode=1975BAMS...56..527.|doi=10.1175/1520-0477-56.5.527|doi-broken-date=2 December 2024 |doi-access=free}}</ref>

Upper level cyclones can exist without the presence of a surface low, and can pinch off from the base of the [[tropical upper tropospheric trough]] during the summer months in the [[Northern Hemisphere]]. Cyclones have also been seen on extraterrestrial planets, such as [[Mars]], [[Jupiter]], and [[Neptune]].<ref name="Brand" /><ref name="WIZ">{{cite web|publisher=[[NASA]]|author=Samantha Harvey|date=2006-10-02|url=http://solarsystem.nasa.gov/educ/themes/display.cfm?Item=hurricane|title=Historic Hurricanes|access-date=2008-06-14|archive-url=https://web.archive.org/web/20080415120400/http://solarsystem.nasa.gov/educ/themes/display.cfm?Item=hurricane|archive-date=2008-04-15|url-status=dead}}</ref> [[Cyclogenesis]] is the process of cyclone formation and intensification.<ref name="Arc">{{cite web|author=Nina A. Zaitseva |year=2006 |publisher=[[National Snow and Ice Data Center]] |url=http://nsidc.org/arcticmet/glossary/cyclogenesis.html |title=Cyclogenesis |access-date=2006-12-04 |url-status=dead |archive-url=https://web.archive.org/web/20060830135741/http://www.nsidc.org/arcticmet/glossary/cyclogenesis.html |archive-date=2006-08-30 }}</ref> [[Extratropical cyclones]] begin as waves in large regions of enhanced mid-latitude temperature contrasts called [[baroclinity|baroclinic zones]]. These zones contract and form [[weather front]]s as the cyclonic circulation closes and intensifies. Later in their life cycle, extratropical cyclones [[occluded front|occlude]] as cold air masses undercut the warmer air and become cold core systems. A cyclone's track is guided over the course of its 2 to 6 day life cycle by the steering flow of the subtropical [[jet stream]].

Weather fronts mark the boundary between two masses of air of different [[temperature]], [[humidity]], and [[densities]], and are associated with the most prominent [[meteorological phenomena]]. Strong cold fronts typically feature narrow bands of [[thunderstorm]]s and [[severe weather]], and may on occasion be preceded by [[squall line]]s or [[dry line]]s. Such fronts form west of the circulation center and generally move from west to east; [[warm front]]s form east of the cyclone center and are usually preceded by [[Stratus cloud|stratiform]] [[precipitation]] and [[fog]]. Warm fronts move [[Geographical pole|poleward]] ahead of the cyclone path. Occluded fronts form late in the cyclone life cycle near the center of the cyclone and often wrap around the storm center.

[[Tropical cyclogenesis]] describes the process of development of tropical cyclones. Tropical cyclones form due to latent heat driven by significant thunderstorm activity, and are warm core.<ref>{{cite web |title=Tropical cyclogenesis |url=http://www-das.uwyo.edu/~geerts/cwx/notes/chap13/trop_cyclogenesis.html |website=www-das.uwyo.edu |access-date=12 January 2021 |archive-date=17 May 2021 |archive-url=https://web.archive.org/web/20210517035428/http://www-das.uwyo.edu/~geerts/cwx/notes/chap13/trop_cyclogenesis.html |url-status=live }}</ref><ref name = "AOML FAQ A7">{{cite web|publisher = [[Atlantic Oceanographic and Meteorological Laboratory]], Hurricane Research Division|title = Frequently Asked Questions: What is an extra-tropical cyclone?|author = Stan Goldenberg|date = 2004-08-13|access-date = 2007-03-23|url = http://www.aoml.noaa.gov/hrd/tcfaq/A7.html|archive-date = 2007-02-09|archive-url = https://web.archive.org/web/20070209121005/http://www.aoml.noaa.gov/hrd/tcfaq/A7.html|url-status = live}}</ref> Cyclones can transition between extratropical, subtropical, and tropical phases.<ref>{{cite journal |last1=Evans |first1=Clark |last2=Wood |first2=Kimberly M. |last3=Aberson |first3=Sim D. |last4=Archambault |first4=Heather M. |last5=Milrad |first5=Shawn M. |last6=Bosart |first6=Lance F. |last7=Corbosiero |first7=Kristen L. |last8=Davis |first8=Christopher A. |last9=Pinto |first9=João R. Dias |last10=Doyle |first10=James |last11=Fogarty |first11=Chris |last12=Galarneau |first12=Thomas J. |last13=Grams |first13=Christian M. |last14=Griffin |first14=Kyle S. |last15=Gyakum |first15=John |last16=Hart |first16=Robert E. |last17=Kitabatake |first17=Naoko |last18=Lentink |first18=Hilke S. |last19=McTaggart-Cowan |first19=Ron |last20=Perrie |first20=William |last21=Quinting |first21=Julian F. D. |last22=Reynolds |first22=Carolyn A. |last23=Riemer |first23=Michael |last24=Ritchie |first24=Elizabeth A. |last25=Sun |first25=Yujuan |last26=Zhang |first26=Fuqing |title=The Extratropical Transition of Tropical Cyclones. Part I: Cyclone Evolution and Direct Impacts |journal=Monthly Weather Review |date=1 November 2017 |volume=145 |issue=11 |pages=4317–4344 |doi=10.1175/MWR-D-17-0027.1 |doi-broken-date=2 December 2024 |bibcode=2017MWRv..145.4317E |s2cid=38114516 |url=https://escholarship.mcgill.ca/concern/articles/gf06g709j |hdl=1959.4/unsworks_47895 |hdl-access=free }}</ref> Mesocyclones form as warm core cyclones over land, and can lead to [[tornado]] formation.<ref name = "FoN"/> [[Waterspout]]s can also form from mesocyclones, but more often develop from environments of high instability and low vertical [[wind shear]].<ref name = "NWS"/> In the Atlantic and the northeastern Pacific oceans, a tropical cyclone is generally referred to as a [[hurricane]] (from the name of the ancient Central American deity of wind, [[Huracan]]), in the Indian and south Pacific oceans it is called a cyclone, and in the northwestern Pacific it is called a [[typhoon]].<ref>{{cite web |url=http://www.aoml.noaa.gov/hrd/tcfaq/A1.html |title=Frequently asked questions |work=Hurricane Research Division |access-date=2006-04-08 |archive-date=2011-03-09 |archive-url=https://web.archive.org/web/20110309163143/http://www.aoml.noaa.gov/hrd/tcfaq/A1.html |url-status=live }}</ref>
The growth of instability in the vortices is not universal. For example, the size, intensity, moist-convection, surface evaporation, the value of potential temperature at each potential height can affect the nonlinear evolution of a vortex.<ref>{{cite journal |last1=Rostami |first1=Masoud |last2=Zeitlin |first2=Vladimir |title=An improved moist-convective rotating shallow-water model and its application to instabilities of hurricane-like vortices |journal=Quarterly Journal of the Royal Meteorological Society |date=July 2018 |volume=144 |issue=714 |pages=1450–1462 |doi=10.1002/qj.3292 |bibcode=2018QJRMS.144.1450R |url=http://hal.sorbonne-universite.fr/hal-01755718/file/Improved_mcRSW_PrePrint.pdf }}</ref>