Mysterious giant ice balls discovered on Swedish coastline

Bird watchers walking along the beach on the Baltic island of Öland off Sweden’s southeastern coast were puzzled by an unusual natural phenomenon recently when they stumbled across dozens of football-sized balls of ice lying on the shore.

... "It's hard to say just how common ice balls are, since we are reliant on witness reports," SMHI spokeswoman Alexandra Ohlsson told The Local.

A review by SMHI of weather conditions on southern Öland in the days leading up to Bladh’s ice ball discovery revealed that temperatures in the area were generally below freezing, with snowfall, and winds from the north and northeast averaging 50 kilometres per hour.

According to SMHI, it was possible that rolls of snow near the shore remained soft due to warmth emanating up from the ground, which could have then been blown into the water by the strong winds.

Once formed, the balls likely came back to shore and, rather than floating out to open water, remained there due to a change in sea conditions in the days before the ice balls were discovered. Water levels sunk several decimetres between December 17th and December 18th when Bladh and his colleagues found the ice balls lying on the shore. ...

via Mysterious giant ice balls discovered on Swedish coastline - The Local.