﻿Smithsonian 
  Report 
  1922. 
  — 
  Humphreys. 
  

  

  Plate 
  2. 
  

  

  I. 
  Advection 
  Fog, 
  Seen 
  from 
  Mount 
  Wilson, 
  Calif. 
  

  

  (F. 
  EJlerman, 
  photo.) 
  

  

  2. 
  Cirrus. 
  

  

  (F. 
  Ellerman, 
  photo.) 
  

  

  