| 
 | 
  .  | 
22 Degree Halo
a ring of light 22 degrees from the sun or moon
 A halo is a ring of light surrounding the sun or moon.
Most halos appear as bright white rings but in some instances,
the dispersion of light as it passes 
through ice crystals found in upper level cirrus clouds 
can cause a halo to have color.
 
[Image:  22 degree halo (45K)]
 Photograph by:
Rauber | 
Halos form when light from the sun or moon is
refracted
 by ice crystals associated with thin, high-level clouds (like
cirrostratus clouds).
A 22 degree
halo is a ring of light 22 degrees from
the sun (or moon) and is the most
common type of halo observed and is formed by hexagonal ice crystals 
with diameters less than 20.5 micrometers. | 
  
  
 |