These rare shapes are formed—under perfect temperature conditions only—when a mass of snow either falls or is blown by the wind. If it manages to catch on to some other snow, and gravity or the wind is in its favor, then the new snowball will roll itself in the exact same way we all used to. In this case, though, the middles tend to collapse to create a donut shape, which can end up as tall as 26 inches (66 cm).