Last week I was walking to the End of the World to help our station manager Weeks dip the fuel tanks when he noticed something unusual – small balls of snow all around us. “Yukimarimos! Haha, not really…those are just ice chunks…They’re way too big to be yukimarimo” He had seen them before, but only around sunrise/sunset. I got down on my knees turning on my red headlamp and gently reached my thick mittened hand towards one. At the slightest touch it rolled away from me picking up speed in the gentle wind. “What?! They really are Yuikimarimos! Those are HUGE!” I turned my head, illuminating dozens surrounding us, some easily 3-4inches (8-11cm) in diameter. They jostled together and rolled off into the darkness in the light breeze. Tiny ones only centimeters across filled in our footprints behind us. It was ~85F below zero with 5 or 6 knots wind.
After lunch we returned to dip more fuel tanks, a very cold task. This time we were joined by a band of excited Yukimarimo hunters armed to the gaiters with red headlamps, tripods, and cameras that would die in the cold after half an hour. I tried to pick one up, but my clumsy oversized mitten crushed it completely. Pulling off my mitten I gently cradled another in my soft glove liners. It was a 3 inch snowball light as air, long hoar frost crystals held together by static electricity. “I dare you to eat it!” Weeks joked, I pulled down my thick fleece neck gaiter that covered my nose, cheeks, and mouth. “No! I was just joking! It’s -85F!” The Yukimarimo melted at the hint of my breath, leaving naught but a drop of water in my mouth. A ball of air held together by frost.
A while later our meteorologist, Phil, found a cache of them hiding under the station itself.
This tricky phenomenon has only recently been scientifically documented (1997)and requires very specific environmental conditions – only forming in the heart of the Antarctic plateau in winter.
“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 researchers gave these dainty formations the name ‘yukimarimo’. ‘Yuki’ is the Japanese for snow, and ‘marimo’ is a globular water plant found in a lake in Hokkaido, Japan’s northern island.”
The full article in Nature can be found here:
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Some pictures from the South Pole.