Another View of Southern New Jersey Circumhorizontal Arc
April 25, 2008
The photo above shows a coquettish circumhorizontal arc peeking between cumulus (cumulus humilis) clouds. On this mid summer’s day of July 22, 2007, in southern New Jersey, the Sun was approximately 70 degrees above the horizon when the photo was taken, and thus it was easily high enough for a circumhorizontal arc to be observed. In order for a circumhorizontal arc to form, the Sun has to be at least 58 degrees above the horizon. This perhaps loveliest of all ice-related arcs forms when sunlight enters the vertical side faces of atmospheric ice crystals and exits through their lower horizontal basal face. See also the Earth Science Picture of the Day for January 16, 2008.