96 The Sky 
cal apparitions reflection may also play a part. All of the 
previous effects were accompanied by coloration because re- 
fraction always exhibits some degree of dispersion. In re- 
HORIZON 
flection, however, white light is not broken up into its com- 
ponent colors, the result being that all halos and rings caused 
by reflection are pure white. One such reflection effect is the 
pp PILLAR OF LIGHT 
parhelic circle, a horizontal circle passing through the sun 
and extending all the way around the sky. Sundogs due to 
reflection may occur at many different positions in the sky, 
but are always the same height above the horizon as the real 
