. Elementary physical geography . vio-lent storms are fortunately small, local, and not common inmost of the country. Like the dust whirl of the desert, orlike the hurricane, they are whirling bodies of air, in whichthe winds blow toward a center, where they rise (Fig. 52).The winds blow at such terrific rates that houses are torn down and the parts carriedaway (Fig. 53). The news-papers furnish vivid descrip-tions of them; and whilethey are often exaggerated,almost no story concerningthe action of tornadoes istoo incredible for the center, where the airis ascending, the air pressur
. Elementary physical geography . vio-lent storms are fortunately small, local, and not common inmost of the country. Like the dust whirl of the desert, orlike the hurricane, they are whirling bodies of air, in whichthe winds blow toward a center, where they rise (Fig. 52).The winds blow at such terrific rates that houses are torn down and the parts carriedaway (Fig. 53). The news-papers furnish vivid descrip-tions of them; and whilethey are often exaggerated,almost no story concerningthe action of tornadoes istoo incredible for the center, where the airis ascending, the air pressureis often so low that a partialvacuum is produced; and the walls of houses may then beblown outward by the sudden expansion of the air the tornado approaches, it appears as a great funnel-shaped column of black cloud (Fig. 52), in which there aresigns of violent commotion. As it comes nearer, a roaringnoise is heard ; and as the cloud overspreads the sky, rain or1 In newspaper accounts they are usually called Fig. of a tornado. STORMS. 105 hail falls ; but this ceases in the violent part of the tornado,where the air is rising so rapidly that these forms of watercannot descend. At first there is no wind, then suddenly agale springs up, and almost immediately its violence becomesso great that houses and trees are felled. On opposite sidesof the storm the wind moves spirally toward the center. The tornado usually progresses at a rate of from 25 tc»40 miles an hour. Its width is rarely as great as a mile,and more often i.,t-
Size: 1896px × 1317px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthortarrralphsralphstockm, bookcentury1900, bookdecade1900
