27. Typical Altostratus, Thick, Mo. 



This view from Mount Washington shows a sheet of altostratus 

 above, with a band of brighter sky near the horizon. This cloud sheet 

 is coded AIj. When progressive development results in the formation 

 of fractostratus or fractocumulus clouds below the altostratus (or 

 nimbostratus) sheet (pi. 17) the lower clouds are then coded L^. 

 (Photo by C. F. Brooks.) 



28. Altocumulus, or High Stratocumulus, at One Level Only, M3. 



The clouds in this photograph would probably be classed as alto- 

 cumulus by the majority of observers. The masses are rather large, 

 however, and could properly be called stratocumulus. The criterion 

 is that the diameters of the snmllest of the well-defined and regularly 

 arranged elements must not exceed the width of three fingers with the 

 arm extended if they are to be called altocumulus. In either case they 

 are coded M3. (Photo taken near Crozet, Va., by A. C. LapsW.) 



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