Snow doughnuts: Ukrainian polar explorers show rare phenomenon at Antarctic station

The National Antarctic Science Centre reports.

"These are multi-layered snowballs, which usually have a void inside. They can be either very small — from a few centimeters in diameter, or quite noticeable — more than a meter in diameter, resembling bales of hay in a field," the report says.

Such a phenomenon is quite rare, including in the Antarctic, although it can be found not only there. This is due to the fact that the formation of snow "doughnuts" requires a number of weather conditions: two different layers of snow (frozen or covered with ice crust and fresh, loose), a temperature close to the ice melting point, a specific wind and slope.