within inflow-outflow interchange areas as RFDs interact with mesocyclones or flanking line updrafts) and streamwise vorticity currents (SVCs) feeding into mesocyclones. Although not considered a separate kind of funnel cloud, some funnel clouds form with mesovortices associated with squall lines, which also can become tornadoes but are often not visible as funnel clouds or tornadoes because they usually occur within obscuring precipitation. Other "fair weather" funnel clouds include horseshoe clouds which are a very transient phenomena associated with extremely weak vortices. See also Dust devil Landspout Whirlwind References External links What is a tornado? (Charles A. Doswell III) Tornado Myths: A funnel cloud needs to touch the ground to be a tornado, OR the visible funnel is the tornado (Dan Robinson) USA Today article on small vortices TORRO Tornado FAQ Cold-core waterspouts over Lake Michigan in fall 2006 news helicopter footage of cold-air funnel clouds in the St. Louis metropolitan area in spring 2007 (KTVI) Accessory clouds Cumulus Tornado Tornadogenesis Microscale meteorology