Employees at the Hvaleyrarvöllur golf course in Hafnarfjörður (Iceland) arrived to an usual site on Friday, RÚV reports: naturally formed rolls of snow all over the frozen green.
According to meteorologist Óli Þór Árnason, such rolls form through a unique combination of specific weather conditions. On Thursday, he explained, it snowed, and then the temperature rose by one or two degrees and little drops of rain fell over the golf course. When that happened, the top layer of the snow got wet, right as the wind kicked up, and that’s how the rolls were shaped.
“It’s a bit of a coincidence—everything needs to happen at the same time,” he said. “[H]umidity and wind, in order for [the snow] to start rolling itself.”