Evening Republican, Volume 21, Number 169, Rensselaer, Jasper County, 27 July 1918 — Tornadoes and Cyclones [ARTICLE]

Tornadoes and Cyclones

Storms as Defined by the LJ. S. Weather Bureau*

Weather men define a tornado as a violent windstorm, with rain or hail, thunder and lightning, in which the air masses whirl with great velocity around a central core, while the whole storm travels across the country in a narrow path at high speed. The thunder and the whirling motion have given rise to two theories of the derivation of the word, as to whether it is derived from the Spanish “tornada,” a thunderstorm, or from the Latin “tornare,” to turn. A cyclone, In the definition of the weather bureau, is not necessarily a windstorm of great velocity, but rather..a widespread storm that moves with no great speed. Its width may cover several states. This cyclone, or area Of low pressure—indicated as “low” on the weather map—gives conditions essential to tornadoes. Many cyclones never develop a tornado, but a tornado never develops without the cyclone, and almost invariably the tornadoes occur in the southeast quarter of the low area. About 120 cyclones pass across the United States each year, moving in a general way from west to east. They are of great benefit because they induce movement of surface air from the squth and southeast, and the rainfall that makes the great Interior valleys a rich agricultural region is dependent upon these southerly, moisture-bearing winds. Practically all of the cyclones of the warm season give rise at some time or place to thunderstorms or hail or violent winds. These winds may be violent enough to cause destruction, but unless they have the whirling column of air they are not tornadoes. In the East it is not always easy to distinguish the funnel-shaped cloud, but the lay of the debris after a storm will tell whether there has been a twisting motion. Tornadoes almost invariably move in an easterly direction and generally from southwest to northeast. The average length of the path of destruction is about 25 miles, and this path may not be continuous, if the funnel cloud is not in contact with the earth during its whole course. Sometimes it rises and goes for a considerable distance before descending again.