Strange clouds over Moscow spark controversy (footage)

Strange clouds appeared in Moscow in the form of a huge ring leaving people to flood the web with videos of the rare phenomenon.

The phenomenon led Moscow's weather forecast service scientist to clarify it was a purely optical effect, according to Russia's paper Vesti 24.

The scientists explained that the phenomenon was produced after the recent flow of several air fronts in Moscow and an inflow of cold air from the Artic, according to the paper.