Solar Arcs of the Arctic
All photos taken by and (c) Bruce G. Marcot.
In May 2009 I was on a study of polar bears on the Beaufort Sea north of Alaska.
When the weather finally cleared, after days of light snow, we took the helicopter out on to the ice of the Arctic Ocean, landing on ice floes dozens of miles from the frozen shore. Ice crystals hung in the lower atmosphere.
There, I spotted this spectacle of solar arcs.
The photo to the left is a stitched mosaic of several photos, as I didn't have a lens with wide enough angle to capture it all in a single shot.
Look carefully at the halo; there is more than one. The photos below explain what is shown here.
Here is a zoomed, color-enhanced view of the bottom part of the arc. Notice how it seems to split on the left. It's a bit subtle here ...
See next photo ...
The top of the arc more clearly splits. (This image is color- and contrast-enhanced to bring out details.)
The bottom part is the circular 22-degree solar halo showing rainbow colors.
The top part is what is called a tangent arc created by ice crystals of horizontal columnar structures.
The tangent arc spreading from the upper part of the 22-degree halo is clearly visible here.
But look closely in the glare of the sunshine inside these arcs ...
The bright white dot is a lens flare; the sun is just below it hidden in the clouds.
But around and just above this lens flare dot is a faint column of white. In the sky, it seemed to faintly split in two upwards.
This is a very rare Moilanen arc, seldom seen or photographed. It is created by ice crystals oriented at 34-degree angles to one another, but little is known exactly how this happens.