"Snow doughnuts": Ukrainian polar explorers share photos of a rare phenomenon

Ukrainian polar explorers from the Akademik Vernadsky station have recorded an unusual snow formation resembling doughnuts. The National Antarctic Scientific Centre of Ukraine noted that this phenomenon is commonly called rollers.

The National Antarctic Science Center emphasizes that this natural find is quite a rare phenomenon, including for the Antarctic. This is stated in a post on the station 's official Facebook page.

Scientists reported that the rollers or so-called "snow doughnuts" are multi-layered snow bundles resembling hay bales in a field, which usually have a void inside. The diameter of such snow rolls can vary from a few centimetres to more than a metre in diameter.

It is noted that the formation of such rolls requires a slope and a number of natural conditions, including:

• Two different layers of snow. The lower one is frozen or covered with an ice crust, which serves as a substrate, and the upper one is fresh, loose and wet, which should cover the lower one but not stick to it;
• Air temperature close to the ice melting point (slightly above 0°C);
• Wind strength that will not destroy but will be enough to move the snow clumps.

"The need for all of these very specific conditions to coincide is what makes snow rollers a unique phenomenon that is rarely seen," the report says.