Sundog (The Rainbow Tree)

Sundog Tree
St. Croix River
Minnesota
© 2012  C. Allen Weekley
All Rights Reserved

A sundog or parhelion is formed by ice crystals aligning vertically as they fall through the atmosphere in very cold weather. This was taken shortly after sunrise, with an ambient temperature of about -5 degrees F. I walked out on a jetty on the frozen St. Croix river and saw a sundog aligned with this tree.