﻿Smithsonian 
  Report 
  1922. 
  — 
  Humphreys. 
  

  

  Plate 
  16. 
  

  

  i: 
  Cumulo-nimbus, 
  Pensacola, 
  Fla. 
  

  

  (Lieut. 
  W. 
  F. 
  Rood, 
  jr., 
  photo.) 
  

  

  2. 
  Cumulo-nimbus, 
  Seen 
  from 
  Mount 
  Wilson, 
  Calif. 
  

   (F. 
  E 
  Herman, 
  photo.) 
  

  

  