|Subsun pictured in winter by John Scurlock (photo galleries) over Three Fingers in the North Cascades Range, Washington State. Image ©John Scurlock
The subsun can often be seen from an airplane as a blinding and shimmering disk or oval. Look down on sunward side of the aircraft at clouds or mist to see it drifting with the 'plane over the clouds or landscape.
The subsun is an ice halo formed by reflection of sunlight from the upper and lower nearly horizontal faces of plate crystals. The crystals act as millions of tiny mirrors to form a reflected image of the sun. When the crystals have larger wobbles from horizontal the subsun becomes a lower sun pillar.
Here the sun is low and the small aircraft is actually flying through diamond dust ice crystals. The resulting subsun seemingly hangs in the air but of course, like all halos and rainbows, it has no corporeal existence.