30 GENERAL SCIENCE 



When cirro-cumulus clouds appear in winter, expect warm and wet weather. 



Mackerel clouds in sky, 

 Expect more wet than dry* 



A mackerel sky, 



Not twenty-four hours dry. 



Mackerel scales and mare's tails 

 Make lofty ships carry low sails. 



Fracto-stratus. Fracto-stratus is the true stratus torn by the 

 wind or mountain summits into irregular fragments. 



Fracto-cumulus. These are broken masses of cloud which are 

 continually changing in form. They are caused by the true Cumu- 

 lus being torn by strong winds into detached parts. Fracto- 

 cumulus clouds present continual changes. 



FIG. 19. Strato-cumulus. 



Strato-cumulus. One-half to 3 miles high. Large balls or rolls 

 of dark clouds which frequently cover the whole sky, especially in 

 winter, and give it at times an undulating appearance. The stratum 

 of Strato-cumulus is usually not very thick. A blue sky often 

 appears in breaks through it. Between this form and the Alto- 

 cumulus all possible gradations are found. It is distinguished from 

 Nimbus by the ball-like or rolled form. It does not tend to bring 

 rain. 



