Having fun with 2 GoPros at very small local hill. The rainbow at the background was real (it is not lens effect). I have never seen such thing during winter
Sundog halo effect with the refracted light circle around the sun as you look towards the Sun, as opposed to a rainbow seen looking away from the sun. Sundogs are pretty common on cold days with thin Cirrus clouds, but I usually see them as a spot rather than a full halo.