INSTRUCTIONS TO MARINE METEOROLOGICAL OBSERVERS 73 



sparse, or else large (at least some of tliem) and close together, while 

 stratus only gives a drizzle, that is to say, small drops, very close 

 top-ether. 



When there is no precipitation, a dark and uniform layer of stratus 

 can easily be mistaken for nimbostratus. The lower surface of nim- 

 bostratus, however, has always a soft appearance (widespread, trail- 

 ing precipitation, "virga") ; it is quite uniform and it is not possible 

 to make out definite detail ; stratus, on the other hand, has a "drier" 



