Democratic Sentinel, Volume 13, Number 30, Rensselaer, Jasper County, 16 August 1889 — What a Cloudburst Is. [ARTICLE]

What a Cloudburst Is.

The phenomena of a cloudburst, which can only occur in a tornado or whirlwind, arc not generally understood, says the New York Herald. The whirl in which it forms is not a very broad and shallow’ disk, but a tall, columnar mass of rotating air, similar to that in which the Atlantic waterspout or the famous pillar-like dust storm of India is generated. While this traveling aerial pillar, perhaps a few hundred yards in diameter, is rapidly gyrating, the centrifugal force, as Prof. FerreJ has shown, acts as a barrier to prevent the flow of external air from all its interior, except at and near the base of the pillar. There friction with the earth, retards the gyrations and allows the air to rush in below and escape upward through the flue-like interior as jiowerful ascending currents. The phenomenon, however, will not be attended by terrific floods unless the atmosphere is densely stored with watefr vapor, as it was on Tuesday in the Cayadutta Valley, and as it was on May 31 in the Conemaugh Valley. When such is the case, the violent ascending currents suddenly lift the va-por-laden clouds several thousand feet above the level at which they were previously floating, and hurl them aloft into rarefied and cold regions of the atmosphere, where their vapor is instantly condensed into many tons of water. Could the water fall as fast as condensed it would be comparatively harmless. But the continuous uprushing currents support this mass of water at high level, and as their own vast volumes of vapor rising are condensed they add to the water already accumulated thousands of feet above the earth’s surface—making, so to speak, a lake in high air. As the whirlwind weakens or passes from beneath this vast body of water, which its ascending currents have generated and upheld in the upper story of the atmosphere, the aqueous mass, no longer supported, drops with everincreasing gravitational force to the earth. In severe cloud bursts the water does not fall as rain, but in sheets and streams, sometimes unbroken for many seconds. The cloud burst of 1838 at Hullidavsburg, Pa., excavated many holes in tne ground,varying from twenty-five to thirty feet in diameter, and from three to six feet deep. In a similar but milder storm, which visited Boulogne last May, fissures were cut in the streets eight feet deep and openings made large enough to engulf a horse and cart.