OCR Text |
Show CrfosS-SECTION OF A THUNDERSTORM Clouds which bring thunderstorms nro compact masses which travol from wost to east nt speeds vurylng from 20 to 40 miles an hour. Thoy presont a concave front as they advance. Tho above Illustration Is a cross suction along tho wost to oust axis. "A" represents tho clrro-strntus blanket with light gray festoons which comes In vtow nbout nn hour beforo tho storm proper. "T" aro underlying cumulo-nimbus clouds, distinguished by omluottv leaden hued nnd mountaln llko "thunder caps." "8" roproscntB tho squnll cloud, sweeping along nt tho surface ot tho earth and causing tho preliminary swirls ot wind, spattering rain or hall. "R" Is tho nctual storm cloud, center of tho rain and electrical disturbance, and "II" tho rain filled spneo between tho earth and lower cloud base. "II" Indicates tbo direction of warm air currents from tho earth drawn Into tho body ot tho storm cloud and supplying supply-ing tho molsturo which regulates tho duration of tho storm. |