3. Cumulus, Heavy and Swelling, Without Anvil Top, L.. 



The large cloud mass in the center has a horizontal, heavily shaded 

 base and shows active vertical development, with heaps in a "cauli- 

 flower" formation. The upper surfaces look hard and are clear cut, 

 hence the central cloud mass has not yet reached the cumulonimbus 

 (is) stage. (Photo at Cheyenne, Wyo., by H. T. Floreen.) 



4. Cumulus, Heavy and Swelling Without Anvil Top, L2. 



These clouds have great vertical development m the form of towers, 

 showing active convection on a warm afternoon. Their height and 

 the absence of any other cloud forms indicate that they are of recent 

 growth. However, the second cloud from the left shows signs of the 

 formation of an anvil and is in a transition stage between Lo and L^. 

 (Photo at Manila, P. I., by C. E. Deppermann.) 



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