Photo: Mike Stanford
Here's how the strange natural phenomonon of snow donut is formed:
"It's formed by a clump of snow falling off of a cliff or a tree into the snow pack. And if the conditions and temperature are just right, as gravity takes over, it pulls the snow down, and it rolls back on itself," Stanford says. "Usually the center collapses and it creates what we call a pinwheel."
But when the hole stays open, it creates a shape that resembles a car tire covered with ice, or a gigantic, white Cheerio.
http://www.npr.org/templates/story/story.php?storyId=8993287 - via Presurfer