Russian HALO! Cloud?

WHAT IS THIS??

I've been seeing this everywhere, it sure is an attention grabber. I really don't know what to make of it, wormhole, vortex or ship, even though it's been tagged as a photoshop job I just don't buy that explanation.

i'll say this first, wow

this explanation from latest zeta comments:
(makes as much sense as anything else)

In the sky on Moscow [Oct 7] has occurred the unusual phenomena: enormous crater with white edge, look like "cloud-ring". As can Zeta to comment the phenomena? Given event was illuminated in some Russian mass media.

(with the same image as in OP)

Air updrafts or downdrafts are not uncommon, the most common form the tornado. Here cold air is above warm air, capping the warm air, so that it is only allowed to rise in weak spots in the cold air layer, causing a swirling tube of warm moist air rising through the cold air layer - the tornado. The circle in the sky over Moscow is an incomplete tornado, in fact the remnant of an incomplete tornado. The cloud cover has been broken as rapidly rising air broke through a cold air cap. The reason the cloud cover seems broken, revealing light only at the edges of the circle, is due to the rapid movement of swirling air at the edges. As is known, a tornado has a calm in the center of the swirling tube, the high winds at the edges of the tube. The calm in the center of an incomplete tornado allows the cloud cover to remain in place, where at the edges of the swirl the cloud cover is torn away.