From Glossary of Meteorology
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  1. In general, any tornado over a body of water.

  2. In its most common form, a nonsupercell tornado over water.

    Such events consist of an intense columnar vortex (usually containing a funnel cloud) that occurs over a body of water and is connected to a cumuliform cloud. Waterspouts exhibit a five- stage, discrete life cycle observable from aircraft: 1) dark-spot stage; 2) spiral pattern stage; 3) spray-ring stage; 4) mature or spray-vortex stage; and 5) decay stage. Waterspouts occur most frequently in the subtropics during the warm season; more are reported in the lower Florida Keys than in any other place in the world. Funnel diameters range from a few up to 100 m or more; lifetimes average 5–10 minutes, but large waterspouts can persist for up to one hour.

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