A waterspout is a funnel cloud over water. It is a nonsupercell tornado over water. Waterspouts do not suck up water; the water seen in the main funnel cloud is actually water droplets formed by condensation. It is weaker than most of its land counterparts.
Types
Non-tornadic
Waterspouts that are not associated with a rotating updraft of a supercell thunderstorm, are known as "nontornadic" or "fair-weather waterspouts", and are by far the most common type.
Fair-weather waterspouts occur in coastal waters and are associated with dark, flat-bottomed, developing convective cumulus towers.
Snowspout
A winter waterspout, also known as a snow devil, an icespout, an ice devil, a snonado, or a snowspout, is a very rare meteorological phenomenon in which a vortex from snow develops that looks like a waterspout. One does not know much about this rare happening and there are only six known pictures of this event so far.
There are three main things that produce a winter waterspout: Very cold temperatures present over a body of warm water enough to produce fog that looks like steam above the water's surface. This usually needs temperatures of -18 °C or colder if the water temperature is no warmer than 5 °C. Lake-effect snows in a small, enclosed or banded formation must be present and going on. The wind speed has to be slow, usually less than 5 knots (9.25 km/h).
Related pages
Winter waterspout
Funnel cloud
Tornado
References
Other websites
British and European Tornado Extremes
A series of pictures from the boat Nicorette getting impressively close to the south coast tornadic waterspout. USA Today online article on waterspouts Home video of a waterspout on Long Island Sound on 27 September 2006 Pictures of cold-core waterspouts over Lake Michigan on 30 September 2006. Archived from the original on March 102007. http://aoss-research.engin.umich.edu/PlanetaryEnvironmentResearchLaboratory/