Halo Display Over Black Rapids Glacier, Alaska

July 16, 2012

Halo Display Over Black Rapids Glacier, Alaska 2

: Lee Petersen 
Summary Author: Lee Petersen; Jim Foster

July 2012 Viewer's Choice The photo above shows a magnificent halo display above the Black Rapids Glacier in the eastern Alaska Range. I photographed this memorable sky (14 images stitched together) while doing fieldwork out on the glacier. The view is to the southeast. It seems as if there are always ice crystals in the atmosphere above Fairbanks and we get to see a lot of interesting optical phenomena, but seeing so many all at once was quite special. Shown here are a circumscribed 22 degree halo (also called the upper and lower tangent arcs of the 22 degree halo), parhelia (sundogs), parhelic circle (extending through the parhelia) and a fragment of a 46 degree halo (at lower left). At times, the parhelic circle made a full circle around our heads. In order to see all of these halos and arcs, at the same time, different types of ice crystals have to be present in the atmosphere throughout the observer's line of sight. Photo taken on April 29, 2012 at 10:45 a.m. 

Photo Details: 0.001 sec (1/1250) exposure; f/14.0 aperture; ISO 250; -1 EV exposure bias.