21. Heavy Cumulus or Cumulonimbus, and Stratocumulus, Lg. 



In the upper part of the picture there is a corrugated sheet of strato- 

 cuniuhis wliich, if it were alone, would be coded L„. However, there 

 are cumulus and cumulonimbus clouds below, some of which pene- 

 trate the stratocumulus. This combination of cumulus and strato- 

 cumulus clouds is coded is. It should be compared with plates 19 

 and 20. (Photo by C. J. P. Cave in the International Atlas.) 



22. Heavy or Swelling Cumulus (or Cumulonimbus) and Ragged 

 Low Clouds of Bad Weather, Ly. 



Cumulus clouds are visible in the distance but a large cumulonimbus 

 cloud has overspread much of the sky with dark fractocumulus clouds 

 which occupy the upper portion of the picture. The presence of a 

 screen of rain falling in the middle distance is shown by the rainbows, 

 primary and secondary. The proper code number is iy. (Photo at 

 Aberdeen Scotland, by G. A. Clarke.) 



58 



