On rare occasions, winter weather and the sea conspire to make ice balls that stack on the beach when they roll ashore. This ball ice, about the size of softballs, covered Stroomi Beach at the Baltic Sea in Estonia in December 2014.
Ball ice is so rare that it made the news last month in Alaska and Finland. Similar to hail, it forms in bays where the water is relatively calm and just cold enough to make ice. A “seed” of ice or grit starts the process, then wind and gentle waves keep turning the floating ball as it grows.
Sometimes two cool things happen at once. In this tweet from NWS APRFC, a field of ice balls in Alaska acquired pointy hats when snow or rime accumulated on one side.
Interesting formation of ice on the banks of the Wulik River near Kivalina. We suspect a combination of strong waves and super cold water created these ice balls. pic.twitter.com/oIM19Jle2N— NWS APRFC (@NWSAPRFC) November 6, 2019
The prettiest ball ice by far were the thousands of white balls covering a beach on Hailuoto Island, Finland in early November. Ranging in size from golf balls to soccer balls, they made international news in photos by Risto Matilla. Island resident Ritva Rundgren filmed them for her Mrs. Santa Claus Finland blog.
Read more about Finland’s ice eggs and see a video of ice balls at Lake Michigan in this article from ScienceAlert.
(photo from Wikimedia Commons; click on the caption to see the original. Video embedded from Mrs. Santa Claus Finland)