Watersprout

Collier's New Encyclopedia (1921)

a remarkable phenomenon occurring for the most part at sea, but occasionally on land, though generally in this latter case in the neighborhood of water. A waterspout at sea is usually formed in the following manner: A dense cloud projects from its center a body of vapor, in form something like a sugar loaf with the point downward. This cone is agitated by the wind till it assumes a spiral form, and gradually dips more and more toward the sea, where a second cone is formed having its point upward. The clouds above and the water below are violently agitated by the physical influences at work. Suddenly the descending and ascending cones of water or vapor meet in mid-air, and form one united pillar which moves onward vertically in calm weather, but obliquely to the horizon when acted on by the wind. The junction of the two cones is generally accompanied by an electric flash. After continuing in this form for a short time the waterspout bursts, in some cases with terrific violence, and to the destruction of anything in the vicinity. Many a ship has been overwhelmed in this manner, and sunk in a moment with all on board. In November, 1885, five vessels were destroyed by a waterspout in the harbor of Tunis. Waterspouts on land are cones or pillars of vapor descending from the clouds. Land waterspouts are usually very destructive in their effects. On Aug. 30, 1878, the town of Miskolcz, in Hungary, was destroyed by a waterspout with considerable loss of life. These phenomena are, however, more common in India than in Europe. One which occurred at Dum-Dum, near Calcutta, was ascertained to be 1,500 feet in height, and it deluged half a square mile of territory to a depth of six inches. The cause of these phenomena has been assumed to be (1) electricity; (2) vortical motion; or (3) a combination of these causes. M. Weyher has, however, succeeded in producing them artificially, and his method shows that vortical motion is the great factor in the production of waterspouts. By means of a rotating tourniquet placed over cold water, an aërial eddy is caused which draws up the water, in the form of a spout composed of drops, to a considerable height; when the water is heated a clearly defined waterspout is seen. With from 1,500 to 2,000 rotations per minute, the vapor from heated water condenses into a visible sheath, enveloping a clearly defined and rarefied nucleus, conical, and tapering downward. As in natural marine spouts, water drops are carried up and thrown out beyond the influences of the upward current.