The Life Cycle of Florida Keys' Waterspouts. I

Abstract

Detailed, multi-faceted analyses show that waterspouts have a characteristic life cycle consisting of five discrete but overlapping stages: 1) the dark spot, a prominent light-colored disc on the sea surface surrounded by a dark patch, diffuse on its outer edges, which represents a complete vortex column from cloud base to sea surface; 2) the spiral pattern, the primary growth phase of the waterspout, characterized by alternating dark- and light-colored surface bands around the dark spot; 3) the spray ring (incipient spray vortex), concentrated around the dark spot, with a lengthening funnel above; 4) the mature waterspout (spray vortex), the stage of maximum overall organization and intensity; and 5) the decay stage, when waterspout dissipation (often abrupt) is initiated by cool downdrafts from a nearby developing rain shower.