Editing Cyclone (section)

===Upper level types===

====Polar cyclone====
{{main|Polar cyclone}}
A '''polar''', '''sub-polar''', or '''Arctic cyclone''' (also known as a [[polar vortex]])<ref name = "glossvortex"/> is a vast area of low pressure that strengthens in the winter and weakens in the summer.<ref>{{cite web|author=Halldór Björnsson |date=2005-01-19 |url=http://andvari.vedur.is/~halldor/HB/Met210old/GlobCirc.html |title=Global circulation |publisher=Veðurstofa Íslands |access-date=2008-06-15 |url-status=dead |archive-url=https://web.archive.org/web/20110807132251/http://andvari.vedur.is/~halldor/HB/Met210old/GlobCirc.html |archive-date=2011-08-07 }}</ref> A polar cyclone is a low-pressure [[weather system]], usually spanning {{convert|1000|km|mi}} to {{convert|2000|km|mi}},<ref>{{cite web |last1=Garima |first1=Khera |title=A vortex of winds-Cyclones – Geography and You |url=https://geographyandyou.com/a-vortex-of-winds-cyclones/ |access-date=14 January 2021 |archive-date=2 March 2021 |archive-url=https://web.archive.org/web/20210302232449/https://geographyandyou.com/a-vortex-of-winds-cyclones/ |url-status=live }}</ref> in which the air circulates in a counterclockwise direction in the northern hemisphere, and a clockwise direction in the southern hemisphere. The Coriolis acceleration acting on  the air masses moving poleward at high altitude, causes a counterclockwise circulation at high altitude. The poleward movement of air originates from the air circulation of the [[atmospheric circulation#Latitudinal circulation features|Polar cell]]. The polar low is not driven by convection as are tropical cyclones, nor the cold and warm air mass interactions as are extratropical cyclones, but is an artifact of the global air movement of the Polar cell. The base of the polar low is in the mid to upper troposphere. In the Northern Hemisphere, the polar cyclone has two centers on average. One center lies near Baffin Island and the other over northeast Siberia.<ref name="glossvortex">{{cite web|author=Glossary of Meteorology|date=June 2000|url=http://glossary.ametsoc.org/wiki/Polar_vortex|title=Polar vortex|access-date=2008-06-15|publisher=[[American Meteorological Society]]|archive-date=2019-07-18|archive-url=https://web.archive.org/web/20190718200838/http://glossary.ametsoc.org/wiki/Polar_vortex|url-status=live}}</ref> In the southern hemisphere, it tends to be located near the edge of the [[Ross ice shelf]] near 160 west longitude.<ref>{{cite journal |last1=Chen |first1=Rui-Rong |last2=Boyer |first2=Don L. |last3=Tao |first3=Lijun |title=Laboratory Simulation of Atmospheric Motions in the Vicinity of Antarctica |journal=Journal of the Atmospheric Sciences |date=December 1993 |volume=50 |issue=24 |pages=4058–4079 |doi=10.1175/1520-0469(1993)050<4058:LSOAMI>2.0.CO;2 |bibcode=1993JAtS...50.4058C |doi-access=free }}</ref> When the polar vortex is strong, its effect can be felt at the surface as a westerly wind (toward the east). When the polar cyclone is weak, significant cold outbreaks occur.<ref>{{cite web|author=James E. Kloeppel|url=http://www.news.uiuc.edu/scitips/01/12weather.html |date=2001-12-01|publisher=[[University of Illinois at Urbana–Champaign]] via the Internet Wayback Machine|title=Stratospheric polar vortex influences winter freezing, researchers say|access-date=2009-12-27 |archive-url = https://web.archive.org/web/20011224094138/http://www.news.uiuc.edu/scitips/01/12weather.html |archive-date=2001-12-24}}</ref>

====TUTT cell====
{{Main|Upper tropospheric cyclonic vortex}}
Under specific circumstances, upper level cold lows can break off from the base of the tropical upper tropospheric trough (TUTT), which is located mid-ocean in the Northern Hemisphere during the summer months. These upper tropospheric cyclonic vortices, also known as TUTT cells or TUTT lows, usually move slowly from east-northeast to west-southwest, and their bases generally do not extend below {{convert|20,000|ft|m}} in altitude. A weak inverted surface trough within the [[trade wind]] is generally found underneath them, and they may also be associated with broad areas of high-level clouds. Downward development results in an increase of [[cumulus cloud]]s and the appearance of a surface vortex. In rare cases, they become warm-core [[tropical cyclone]]s. Upper cyclones and the upper troughs that trail tropical cyclones can cause additional outflow channels and aid in their intensification. Developing tropical disturbances can help create or deepen upper troughs or upper lows in their wake due to the outflow jet emanating from the developing tropical disturbance/cyclone.<ref name="CLARK">{{cite web|author = Clark Evans|url = http://flhurricane.com/cyclone/showflat.php?Cat=0&Number=64429&an=0&page=0|title = Favorable trough interactions on tropical cyclones|publisher = Flhurricane.com|date = January 5, 2006|access-date = 2006-10-20|archive-url = https://web.archive.org/web/20061017001243/http://flhurricane.com/cyclone/showflat.php?Cat=0&Number=64429&an=0&page=0|archive-date = October 17, 2006|url-status = dead}}</ref><ref name="AMSPAPER">{{cite journal|author1=Deborah Hanley |author2=John Molinari |author3=Daniel Keyser |title = A Composite Study of the Interactions between Tropical Cyclones and Upper-Tropospheric Troughs|date=October 2001|journal = [[Monthly Weather Review]]|publisher = [[American Meteorological Society]]|volume = 129|issue = 10|pages = 2570–84|doi = 10.1175/1520-0493(2001)129<2570:ACSOTI>2.0.CO;2|bibcode = 2001MWRv..129.2570H   |doi-access = free}}</ref>