These tyre-shaped Snow Donuts are entirely natural. They are found mostly in the open Prairies of North America. The weather conditions that are needed for these to form include wind, temperature, snow, ice and moisture. A Snow Doughnut can range in size from a tennis ball to more than half a metre tall. They start out as a thick slab of snow; the weather has to be bright and sunny enough for the surface layer to be wet and lose; then a fairly strong wind is required for it to roll. Also, the snow needs to have just the right amount of elasticity.
Snow Donuts
