A cloud column or inverted cloud cone, pendant from a cloud base. Tubas occur mostly with cumulus or cumulonimbus; when it reaches the earth’s surface it constitutes the cloudy manifestation of an intense vortex, namely a tornado or waterspout.
(trumpet) commonly called funnel cloud; also called pendant cloud, tornado cloud: Cloud column or inverted cloud cone, protruding from a cloud base; it constitutes the cloudy manifestation of more or less intense vortex, namely, a tornado or waterspout.