Residents of St. Petersburg in Russia were in for a surprise when they spotted blue snow falling in their city. The entire place was covered in a blanket of blue snow overnight, shocking the residents and leaving them without explanation.
The weird phenomenon was recorded on video and people have already started speculating about possible causes behind this aberration of nature. Some are saying that the blue colour of the snow might indicate extreme levels of atmospheric pollution.
Toxic chemicals like cobalt or methylene blue, which are used in some medical treatments, can give such a colour to snow if they are present in increased levels in the air.
Another possible reason was said to be the demolition of St. Petersburg's chemical-pharmaceutical research institute. In all probability, the chemical products and residues from the industry could have influenced the snowfall, reports Mirror.
Samples of the uniquely coloured snow have been collected by officials at Russia's environmental agency Rosprirodnadzor for analysis. An investigation is being carried out into the incident and the results are expected on Friday, December 29.
Previously, blue snow had fallen on another Russian city, Chelyabinsk, in February 2015. Chelyabinsk is about 1500 miles to the east of St. Petersburg. An investigation into the previous incident revealed that the blue colour had come from the excess use of food colouring in Easter eggs.
Apparently, the blue dye got into the ventilation system of a factory and been sprinkled into the atmosphere. However, people are still unsure how food colouring could have reached the clouds and fallen down with snow.
This time, people are expecting the blue snow to be a result of chemical pollution and wondering whether it can harm the residents of the city. In Siberia's Omsk, pollution had turned snow into black. A local power plant was behind the incident.
Check out how St. Petersburg looked after the weird weather phenomenon: