238 



THE WEATHER 



point and will not pass over your locality at "Z." It follows 

 that, if you receive any rain at "Z," the rain clouds will ap- 

 proach from the direction "A." 



264. To Foresee Showers ; the Clouds that May Rain. 

 After finding the direction from which shower clouds may 



FIG. 169. Growing shower clouds. 



In A, the growing cloud, R, which is ahead of the main thunder shower, 

 begins to rain just as it reaches the observer at Z. Side view. 



In B, the growing cloud, S, follows the main storm, and begins to rain just 

 as it reaches the observer at Z. Sometimes this occurrence gives the impres- 

 sion that the departed shower has returned. Side view. 



In C, the small clouds, a, b, c, d, move eastward, but grow rapidly and begin 

 to rain at the broken line. The edge of the shower thus reaches the observer 

 at Z. Top view. 



In Z) a similar development accompanies a shower that is moving by to 

 southeast of observer's locality. Top view. 



come, the next step is to watch for the approach of clouds that 

 might rain in your vicinity. Broadly speaking, these will be 

 in either of two classes (Figs. 168 and 169) : 



A. Showers already in operation, that come from the direction "A" 

 and move over your locality at "Z" (Fig. 168). As a rule, with 

 a little attention, these may be seen some time in advance. 



B. Growing clouds, not yet raining, that travel toward you from the 

 direction "A" and begin to rain before passing over you. Such 

 clouds may be grouped into two classes: 



