Funnel cloud 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 descending 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
Cloud seeding is used to increase precipitation in areas experiencing drought, to reduce the size of hailstones that form in thunderstorms, and to reduce the amount of fog in and around airports. In the summer of 1948, the usually humid city of Alexandria, Louisiana, under Mayor Carl B. Close, seeded a cloud with dry ice at the municipal airport during a drought; quickly 0.85 inches of rainfall occurred. Cloud seeding is occasionally used by major ski resorts to induce snowfall. Eleven western states and one Canadian province (Alberta) have ongoing weather modification operational programs. In January 2006, an $8.8 million cloud seeding