Writing in the August issue of the Journal of Glaciology, T. Kameda of the Kitami Institute of Technology, Kitami, Hokkaido, Japan and colleagues describe the formation of natural snowballs at Dome Fuji station in Antarctica. However, before small children clamour to be sent there, a few details of the conditions under which they form may perhaps deter them. These balls of snow form best deep in the Antarctic winter, when the air temperature is below minus 60 °C (minus 76 °F), and there is a gentle wind blowing - conditions under which even well-equipped polar explorers stay in heated buildings. In this frigid environment, delicate needles of hoar frost form on the surface of the snow. Some of these are rolled about by the wind and create these fragile snowballs, which grow to a size of about 30 mm.
The balls develop on the surface of the ice in less than 24 hours - understandably, Kameda's team only examined the ground once a day under such rigorous conditions. Once the snowballs have formed, the wind trundles them along the ground until they collect in small wind-carved hollows in the snow.
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