Editing Thunderstorm (section)

===Tornadoes and waterspouts===
[[File:F5 tornado Elie Manitoba 2007.jpg|thumb|right|In June 2007, the town of [[Elie, Manitoba]] was struck by an [[Fujita scale|F5]] [[2007 Elie, Manitoba tornado|tornado]].]]
{{Main|Tornado|Waterspout}}

A tornado is a violent, rotating column of air in contact with both the surface of the earth and a cumulonimbus cloud (otherwise known as a thundercloud) or, in rare cases, the base of a [[cumulus cloud]]. Tornadoes come in many sizes but are typically in the form of a visible [[Funnel cloud|condensation funnel]], whose narrow end touches the earth and is often encircled by a cloud of [[debris]] and [[dust]].<ref name="Renno">{{cite journal |last = Renno |first = Nilton O. |title = A thermodynamically general theory for convective vortices |journal = [[Tellus A]] |volume = 60 |issue = 4 |pages = 688–99 |date=August 2008 |url = http://vortexengine.ca/misc/Renno_2008.pdf |doi = 10.1111/j.1600-0870.2008.00331.x |bibcode=2008TellA..60..688R|hdl = 2027.42/73164 |hdl-access = free }}</ref> Most tornadoes have wind speeds between {{convert|40|and|110|mph|km/h|abbr=on}}, are approximately {{convert|75|m|ft}} across, and travel several kilometers (a few miles) before dissipating. Some attain wind speeds of more than {{convert|300|mph|km/h|abbr=on}}, stretch more than {{convert|1600|m|mi|0}} across, and stay on the ground for more than 100&nbsp;kilometres (dozens of miles).<ref name="SPC FAQ">{{cite web| url = http://www.spc.noaa.gov/faq/tornado| title = The Online Tornado FAQ| access-date = 8 September 2006| last = Edwards| first = Roger |author-link= Roger Edwards (meteorologist) | date = 4 April 2006| publisher = [[Storm Prediction Center]]}}</ref><ref name="fastest wind">
{{cite web| url = http://cswr.org/dow/DOW.htm| title = Doppler On Wheels| access-date = 29 December 2006| publisher = Center for Severe Weather Research| date = 2006| url-status = dead| archive-url = https://web.archive.org/web/20070205124033/http://www.cswr.org/dow/dow.htm| archive-date = 5 February 2007}}</ref><ref name="widest tornado">{{cite web| url = http://www.crh.noaa.gov/oax/archive/hallam/hallam.php| title = Hallam Nebraska Tornado | access-date = 8 September 2006| publisher = Omaha/Valley, NE Weather Forecast Office | date = 2 October 2005}}</ref>

The [[Fujita scale]] and the [[Enhanced Fujita Scale]] rate tornadoes by damage caused. An EF0 tornado, the weakest category, damages trees but does not cause significant damage to structures. An EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers. The similar [[TORRO scale]] ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes.<ref>{{cite web|url=http://www.torro.org.uk/TORRO/ECSS_Slide_Show/2004%20SPAIN%20ECSS%20Post-FINAL%20slide%20show.html |title=Wind Scales: Beaufort, T – Scale, and Fujita's Scale |author=Dr. Terence Meaden |publisher=Tornado and Storm Research Organisation |date=2004 |access-date=11 September 2009 |url-status=dead |archive-url=https://web.archive.org/web/20100430211910/http://www.torro.org.uk/TORRO/ECSS_Slide_Show/2004%20SPAIN%20ECSS%20Post-FINAL%20slide%20show.html |archive-date=30 April 2010 }}</ref> [[Pulse-Doppler radar|Doppler]] [[weather radar|radar]] data, [[photogrammetry]], and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and award a rating.<ref name="EF SPC">{{cite web | title = Enhanced F Scale for Tornado Damage| author = Storm Prediction Center| publisher=[[National Oceanic and Atmospheric Administration]]| url = http://www.spc.noaa.gov/efscale/ef-scale.html| access-date = 21 June 2009 }}</ref>

[[File:Great Lakes Waterspouts.jpg|thumb|right|Formation of numerous waterspouts in the [[Great Lakes]] region (North America)]]

Waterspouts have similar characteristics as tornadoes, characterized by a spiraling funnel-shaped wind current that form over bodies of water, connecting to large cumulonimbus clouds. Waterspouts are generally classified as forms of tornadoes, or more specifically, non-[[supercell]]ed tornadoes that develop over large bodies of water.<ref>{{cite web|url=http://amsglossary.allenpress.com/glossary/search?p=1&query=Waterspout|title=Waterspout|date=2009|access-date=11 September 2009|publisher=[[American Meteorological Society]]|url-status=dead|archive-url=https://web.archive.org/web/20080620115657/http://amsglossary.allenpress.com/glossary/search?p=1&query=waterspout|archive-date=20 June 2008}}</ref> These spiralling columns of air frequently develop within tropical areas close to the [[equator]], but are less common within areas of [[high latitude]].<ref>{{cite web|url=http://www.erh.noaa.gov/btv/events/15Jan2009/overview.shtml|title=15 January 2009: Lake Champlain Sea Smoke, Steam Devils, and Waterspout: Chapters IV and V|author=[[National Weather Service]] Forecast Office, [[Burlington, Vermont]]|publisher=Eastern Region Headquarters|date=3 February 2009|access-date=21 June 2009}}</ref>