WATERSPOUT. A small, rapidly whirling column of air, extending from a cloud down to the ocean or lake, and whose central axis becomes visible as a column of water or cloudy vapor. In some regions, in warm weather. waterspouts are of very frequent occurrence. As they fre quently occur in calm weather, it is evident that they are not necessarily produced by wind, but that, on the contrary, the wind that accompanies them is the result of the same process that forms the spout. The formation of a waterspout is due to a strong indraught upward beneath the base of a cumulus cloud. The air that supplies this indraught easily acquires a rapid rotary motion as it ascends. This rotation, by reason of the re sulting centrifugal force, produees a very decided low pressure in the central axis of the eddy. The rising air flowing into this region expands by reason of the low- pressure, and is therefore cooled dynamically so as to become a visible cloud. One may see a perfect axial cloud formed in a precisely analogous manner in the midst of a rapid dust whirl over a city The permanence of the waterspout axis depends largely upon the humidity of the intlowing A large waterspout is attended by a cloud of flying salt water spray at its base. but the spout
proper consists of fresh water in the form of cloud-particles o• rain. Heavy rain generally falls upon any vessel that runs into a water spout, but the only real danger in that case is from the whirling wind. The firing of cannon to break up a distant spout has often been tried at sea, but it is an error to believe that it has any appreciable effect. Spouts generally last Ind a few minutes, indiVidually, but many of them may form and ilisappear in succession, owing to meteorological in Ihnuices. The term 'waterspout' is often erroneously applied to any very heavy fall of rain from a cloud causing local destructive floods. Such rains may de liver five, ten, or fifteen inches of water in depth over a small region within an hour's time, and cause great destruction. The popular term 'cloudburst' should be applied in these eases, and not the term 'waterspout.' Consult: Fer rel. Recent Advances (Washington, 1335) ; id., Popular Treatise on the Winds (New York, ISSN.