22° halo on snow surface with horizontal color segments
This 22° halo was seen on a thin snow layer which formed on a freshly frozen river from power plant induced precipitation and freezing mist. The dark area inside the 22° halo is prominent, indicating well developed solid crystals that scatter light only at halo angles.
The photo shows also broad horizontal segments of cyan and magenta in the outer areas of 22° halo. These segments seem to be very sensitive to the variations in the camera positioning, changing their position relative to the 22° halo and ground features, as shown by other photos taken by Peter Vancoillie.
I have no explanation to offer. The display was seen in Ghent, Belgium on 21 December 2007.