http://www.fox4kc.com/news/wdaf-mosc...,3963302.story
I read about this and checked around on the Net, and seriously...WTF?!
Apparently, a Moscow weather department spokesperson offered this as an explanation: “Several fronts have been passing through Moscow recently, there was an intrusion of the Arctic air too, the sun was shining from the west — this is how the effect was produced. This is purely an optical effect, although it does look impressive.”
Freaky.