Circumscribed Halo Above Quebec

June 15, 2005


Provided and copyright by: Dominic Cantin
Summary authors & editors: Dominic Cantin; Jim Foster

The above photo shows a fine example of a circumscribed halo, which was visible over Quebec, Canada on May 9, 2005. These halos are more ellipsoidal than circular and surround (circumscribe) the 22 degree halo. For this to occur, the Sun must be higher than about 30 degrees above the horizon. Circumscribed halos form from singularly oriented, column-shaped ice crystals. Light enters through one of the side faces of a crystal and exits through an alternate side face. Circumscribed halos tend to have brighter and sharper colors than do 22 degree halos.

Photo Details: 16mm fisheye lens at f22, 1/500 sec, Fuji Superia 200 film.

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