Upload & Sell: On
I think its a similar effect to a brocken spectre (but in reverse), caused by diffraction of the sunlight by ice crystals or water droplets that are between the observer and the light source. It may not have been raining, but I'm sure there was some moisture in the atmosphere. I have also seen this happen when wind blows a little snow off the trees and it floats around. Either way its diffraction of some sort.