Why one of the cloud rays in the image above stands out by its copper coloring? That's what was in Juho Pöllänen's mind when he posted this and a handful of other images of his sighting in Taivaanvahti.
It must be because it is a reflection subsun. A similar darker hue relative to lighter cloud rays has been evident in a couple of other observations too. Possibly the coloring takes place because of the additional distance reflection subsun light rays have to travel in the lowest layers of atmosphere.
Pöllänen took the photos on October 10, 2015. Another observation in Oulu, on May 10, 2016 by an anonymous observer, shows what appears to be a reddish reflection subsun low at the horizon.
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