INSTRUCTIONS TO MARINE METEOROLOGICAL OBSERVERS 71 



The elements of thick stratocimiukis often tend to fuse together 

 completely, and the layer can, in certain cases, change into nimbo- 

 stratus. The cloud is called nimbostratus when the cloud elements of 



stratocumulus have completely disappeared and when, owing to the 

 trails of falling precipitation, the lower surface has no longer a clear- 

 cut boundary. 



Stratocumulus can change into stratus, and vice versa. The 

 etratus being lower, the elements appear very large and very soft, 

 so that the structure of regularly arranged globular masses and 

 waves disappears as far as the observer can see. The cloud will be 

 called stratocumulus as long as the structure remains visible. 



