236 



THE WEATHER 



ing, and to travel without law or system of movement. This 

 makes it a troublesome type of weather to those in outdoor 

 occupations. But in most sections of the United States both 

 the developing of these showers and the paths they will follow 

 may usually be known some time in advance. 



262. Showers from the Larger Cumuli. A cumulus cloud 

 that is likely to rain nearly always builds up higher than others 



FIG. 167. Diagram of a typical thunderstorm. 



A, B. Warm air flowing into and up through the cloud, largely from in 

 front but often also from sides. 



Z). Downward movement of air within a portion of the storm. 



Z. Cirro-stratus advance sheet extending often far in front. 



M , N, R. Lower clouds in front of storm, almost any size and amount may 

 be present. 



G. Outflowing wind of storm front. 



X. Squall cloud, a ragged roll mixing and tumbling; not always present. 



T. Front of main cloud. 



H, K. Points mentioned in discussing hail. 



V. Backward flow of air in rear of storm; not always present. 



near by, and generally becomes denser in structure so that 

 its bottom is darker. The high top is usually of rather solid 

 texture, and is brilliant white or golden- white on the sunny 

 side and dark on the shaded side. When rain begins to fall a 

 wispy fiber-like fringe appears at the top of the raining portion 

 (Figs. 160, B, and 162, A). As the shower develops, this fringe 

 at the top spreads out in front and often on both sides, and 

 sometimes also to the rear. It extends much the farthest in 



