Funnel cloud - wikipedia Funnel cloud For the album of the same title by Hem, see Funnel Cloud ( album ). This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( October 2012 ) The funnel cloud that developed into the 2007 Elie, Manitoba tornado A funnel cloud obstructed by scud at Garden of the Gods near Colorado Springs, Colorado A funnel cloud is a funnel - shaped cloud of condensed water droplets, associated with a rotating column of wind and extending from the base of a cloud ( usually a cumulonimbus or towering cumulus cloud ) but not reaching the ground or a water surface. A funnel cloud is usually visible as a cone - shaped or needle like protuberance from the main cloud base. Funnel clouds form most frequently in association with supercell thunderstorms. If a funnel cloud touches the ground it becomes a tornado. Most tornadoes begin as funnel clouds, but many funnel clouds do not make ground contact and so do not become tornadoes. Also, a tornado does not necessarily need to have an associated condensation funnel -- if strong cyclonic winds are occurring at the surface ( and connected to a cloud base, regardless of condensation ), then the feature is a tornado. Some tornadoes may appear only as a debris swirl, with no obvious funnel cloud extending below the rotating cloud base. In cloud nomenclature, any funnel - or inverted - funnel - shaped cloud depending from cumulus or cumulonimbus clouds is technically described as an accessory feature called tuba. The terms tuba and funnel cloud are nearly but not exactly synonymous ; a wall cloud, for example, is also a form of tuba. Contents 1 Cold - air funnel clouds 2 See also 3 References 4 External links Cold - air funnel clouds Cold - air funnel clouds ( vortices ) are usually short - lived and generally much weaker than the vortices produced by supercells. Although cold - air funnels rarely make ground contact, they may touch down briefly and become weak tornadoes or waterspouts. A shear funnel extending from a generic cumulus cloud. Observed in northern Texas by a member of the VORTEX project. Unlike the related phenomenon associated with severe thunderstorms, cold - air funnels are generally associated with partly cloudy skies in the wake of cold fronts, where atmospheric instability and moisture is sufficient to support towering cumulus clouds but not precipitation. The mixing of cooler air in the lower troposphere with air flowing in a different direction in the middle troposphere causes the rotation on a horizontal axis, which, when deflected vertically by atmospheric conditions, can become a funnel cloud. They are a common sight along the Pacific Coast of the United States, particularly in the spring or fall. On July 29, 2013, a cold - core funnel cloud touched down as an EF0 tornado in Ottawa, Canada, causing extensive damage in the form of downed trees on a golf course. No advance weather watches or warnings were issued by Environment Canada, and the tornado was spawned from one of the few non-severe storm clouds moving through the area. See also Tornado Dust devil Landspout References ^ Jump up to : Cooley J.R., and M.E. Soderberg, 1973 : Cold air funnel clouds. NOAA Tech. Memo. NWS CR - 52, Scientific Services Division, NWS Central Region, Kansas City, MO, 29 pp. Jump up ^ http://www.cbc.ca/news/canada/ottawa/story/2013/07/30/ottawa-funnel-clouds-storm-video.html Jump up ^ Lypny, Natascia ( July 30, 2013 ). `` ' Cold core funnels ' give Ottawa commuters a twister fright ''. ottawacitizen.com. Archived from the original on August 1, 2013. Retrieved August 2, 2013. External links Wikimedia Commons has media related to Funnel cloud. USA Today article on small vortices TORRO Tornado FAQ Cold - core waterspouts over Lake Michigan in fall 2006 Bluestein, Howard B. ( July 2008 ). `` A Funnel Cloud in a Convective Cloud Line to the Rear of a Surface Cold Front ''. Monthly Weather Review. American Meteorological Society. 136 ( 7 ) : 2786 -- 95. Bibcode : 2008MWRv... 136.2786 B. doi : 10.1175 / 2007MWR2357. 1. Cloud genera and selected species, supplementary features, and other airborne hydrometeors - WMO Latin terminology except where indicated Extreme - level Polar mesospheric cirriform type Noctilucent Very high - level Polar stratospheric cirriform type Nacreous High - level Tropospheric cirriform, stratiform, and stratocumuliform genera Cirrus ( Ci ) Cirrostratus ( Cs ) Cirrocumulus ( Cc ) General type ( non-WMO terminology ) Aviaticus cloud ( Contrail ) Medium - level Tropospheric stratiform and stratocumuliform genera Altostratus ( As ) Altocumulus ( Ac ) Stratocumuliform species Altocumulus castellanus ( Ac cas ) Low - level Tropospheric stratiform, stratocumuliform and cumuliform genera Stratus ( St ) Stratocumulus ( Sc ) Cumulus ( Cu ) Stratiform and cumuliform species Fractus Cumulus humilis ( Cu hum ) Stratocumulus variants ( non-WMO terminology ) Actinoform cloud Asperitas Moderate vertical Tropospheric stratiform and cumuliform genera Nimbostratus ( Ns ) Cumulus ( Cu ) Cumuliform species Cumulus mediocris ( Cu med ) Cumuliform supplementary features Cumulus Pileus Cumulus Volutus Towering vertical Tropospheric cumulonimbiform genus Cumulonimbus ( Cb ) Cumuliform species Cumulus congestus ( ICAO term Towering cumulus ( Tcu ) ) Cumuliform and cumulonimbiform supplementary features mamma Tuba ( Funnel cloud ) Pileus Arcus ( Shelf ) Cumuliform and cumulonimbiform variants ( non-WMO terminology ) Wall cloud Cumulonimbuus Overshooting top Hot tower Surface based General type Fog Non-height specific General types Accessory cloud Kelvin -- Helmholtz cloud Special Special modifiers Flammagenitus ( cloud ) Homogenitus ( cloud ) Retrieved from `` https://en.wikipedia.org/w/index.php?title=Funnel_cloud&oldid=787350950 '' Categories : Accessory clouds Cumulus Tornado Tornadogenesis Hidden categories : Articles needing additional references from October 2012 All articles needing additional references Talk Contents About Wikipedia Afrikaans Deutsch Español Français Italiano עברית Magyar Nederlands 日本 語 Polski Simple English Suomi Edit links This page was last edited on 24 June 2017, at 22 : 09. 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Question: when does a funnel cloud become a tornado
Answer: If a funnel cloud touches the ground