LOCAL STORMS 237 



front, since the air current carrying the cloud moves faster 

 above and so brushes the fringe ahead (Fig. 167, Z). 



263. Showers ; to Foresee Their Coming ; the Path of the 

 Cumulus. To foresee the coming of local showers, first find 

 the direction of path being followed by the larger cumuli. 

 Lower cumuli or stratus may be present at the same time and 

 may move in one or more directions. But in finding the 

 shower path the higher cumuli are the ones to watch. To find 

 the direction they are moving, take a position so that some 

 conspicuous point on the cloud is directly 

 in line with a convenient fixed point of roof 

 or chimney or tower. Hold the head mo- 

 tionless and continue to " sight" past the 

 chimney (or fixed point) to the cloud. As 

 the cloud travels it will seem to move away 

 from the chimney. Note carefully the 

 direction it follows. If, for example, the 

 cloud is exactly in the southwest, as A, 



,,. nco ' ' FIG. 168. The path 



Fig. 168, and appears to move directly O f a cloud, 

 toward Z (the point overhead), then the 

 cloud is following the direction A-Z, which in this figure is 

 from the southwest. If the cloud moves toward a point west 

 of the zenith (point overhead), as toward Y, it is traveling 

 in the direction A-Y. And if it moves toward a point east of 

 the zenith, as X, the cloud is traveling in the direction A-X. 

 Try to select a cloud and a place to stand, so that the cloud 

 you are watching will move either directly toward the zenith 

 or directly away from the zenith, as that makes it easier to 

 find the direction accurately. Among the middle and upper 

 types (Fig. 155) all clouds of the same kind and same height, 

 within your horizon, are moving in the same direction. This 

 is not always true of lower clouds. 



If, then, a large cumulus at A (Fig. 168) is moving in the 

 direction A-Z } all similar clouds are moving in the same 

 direction. And such clouds, or showers from them, that 

 appear at "B" or " D" will travel in the direction the arrows 



