This photograph was taken from the window of an airplane. It is of a beautiful atmospheric phenomenon called the glory, shining in one direction directly opposite the sun. This circular bow is often seen on the tops of stratus clouds with relative uniformity and composed of water drops (not ice crystals). The shadow of the plane is the center, or in the case of mountain climbers, it is of the shadow of your head on top of mountains with clouds below and sunshine above.
Image Courtesy of Franz Kerschbaum, University of Vienna