INSTRUCTIONS TO MARINE METEOROLOGICAL OBSERVERS 55 



and obliterate its contour. This wonkl also be the case with patches 

 of altostratus, but cirrus is distino-uished by its daz/.ling whiteness 

 and silky edges. 



'Halos are rather rare in cirrus. 



Cirrocumulus. — A cirriform layer, or patch composed of small 

 white flakes or of very small globular masses, without shadow^s, 

 which are arranged in groups or lines, or more often in ripples re- 

 sembling those of the sand on the seashore (fig. 16). 



In general, cirrocumulus represents a degraded state of cirrus and 

 cirrostratus, both of which may change into it. In this case the 

 changing patches often retain some fibrous structure in places. 



