Infralateral arc at high sun elevation

Not everything that is apparently a circumhorizontal arc is really one. I saw this halo on 8 July 2009 on Mount Spitzstein (1596m) at the German-Austrian Border. Besides a complete circumscribed halo, a reddish brightening appeared in the CHA-area. I was very delighted to see my first CHA this year, but the arc became longer and rounder ( 1 ). It was obvious that the arc was not parallel to the horizon. Therefore it had to be an infralateral arc. The sun elevation was 60.6°. ( 2 - 3 )

Text: Claudia Hinz