Editing Cyclone (section)

==Structure==
[[File:Post-Tropical Cyclone Nuri and Typhoon Haiyan surface analysis.png|thumb|right|Comparison between extratropical and tropical cyclones on surface analysis]]
There are a number of structural characteristics common to all cyclones.  A cyclone is a [[low-pressure area]].<ref name="FAQ eye">{{cite web|author=[[Chris Landsea]] and Sim Aberson|title=Subject: A11) What is the "eye"? How is it formed and maintained ? What is the "eyewall"? What are "spiral bands"?|url=http://www.aoml.noaa.gov/hrd/tcfaq/A11.html|date=August 13, 2004|publisher=[[Atlantic Oceanographic and Meteorological Laboratory]]|access-date=2009-12-28|archive-date=2006-06-14|archive-url=https://web.archive.org/web/20060614205417/http://www.aoml.noaa.gov/hrd/tcfaq/A11.html|url-status=live}}</ref> A cyclone's center (often known in a mature tropical cyclone as the [[eye (cyclone)|eye]]), is the area of lowest atmospheric pressure in the region.<ref name="FAQ eye"/> Near the center, the [[pressure gradient force]] (from the pressure in the center of the cyclone compared to the pressure outside the cyclone) and the [[force]] from the [[Coriolis effect]] must be in an approximate balance, or the cyclone would collapse on itself as a result of the difference in pressure.<ref>{{cite web|url=http://homepages.abdn.ac.uk/wpe001/meteo/metoh8.pdf|title=The Atmosphere in Motion|publisher=[[University of Aberdeen]]|access-date=2011-09-11|url-status=dead|archive-url=https://web.archive.org/web/20121018224041/http://homepages.abdn.ac.uk/wpe001/meteo/metoh8.pdf|archive-date=2012-10-18}}</ref>

Because of the [[Coriolis effect]], the wind flow around a large cyclone is counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.<ref>{{cite web|author=Chris Landsea|date=2009-02-06|url=http://www.aoml.noaa.gov/hrd/tcfaq/D3.html|title=Subject: D3) Why do tropical cyclones' winds rotate counterclockwise (clockwise) in the Northern (Southern) Hemisphere?|access-date=2009-12-28|publisher=[[Atlantic Oceanographic and Meteorological Laboratory]]|author-link=Chris Landsea|archive-date=2009-01-06|archive-url=https://web.archive.org/web/20090106113522/http://www.aoml.noaa.gov/hrd/tcfaq/D3.html|url-status=live}}</ref> In the Northern Hemisphere, the fastest winds relative to the surface of the  Earth therefore occur on the eastern side of a northward-moving cyclone and on the northern side of a westward-moving one; the opposite occurs in the Southern Hemisphere.<ref>{{cite web|url=https://www.usatoday.com/weather/resources/askjack/wfaqhur.htm|title=Are the winds on one side of a hurricane faster than on the other side?|series=Ask the Experts: Hurricanes|work=[[USA Today]]|date=November 11, 2007|access-date=September 9, 2011|archive-date=October 12, 2011|archive-url=https://web.archive.org/web/20111012204835/http://www.usatoday.com/weather/resources/askjack/wfaqhur.htm|url-status=dead}}</ref> In contrast to low-pressure systems, the wind flow around high-pressure systems are clockwise ([[anticyclonic]]) in the northern hemisphere, and counterclockwise in the southern hemisphere.