Space & Innovation

Snowballs Form Spontaneously, Roll On

Snow rollers -- about a foot and a half wide and some of them hollow -- make a rare appearance in Idaho. Continue reading →

Here's the sort of thing that you might expect to see on the reboot of "The X-Files." Thousands of snowballs spontaneously form, without any human hands to help, and then roll together like a ghostly invasion force through a field in Idaho.

But as agent Mulder probably would explain to us, all those snowballs actually are a natural, albeit extremely rare, phenomenon known as snow rollers.

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As the National Oceanic and Atmospheric Administration's website explains, snow rollers form when an unusual sequence of events occur. First, a smooth crust of snow that's already on the ground is covered by newer, lighter layer of snow. Then, the weather abruptly changes, warming rapidly, and strong wind kicks up. The wind picks up small pieces of moist, sticky snow and sends them rolling along. Once the pieces are on the move, they collect more snow around them.

While snow rollers often are cylindrical, the ones in Idaho formed spherical shapes that resembled snowballs. Unlike the ones you threw at your neighbors as a kid, snow rollers aren't packed together firmly, and sometimes they're even hollow.

While snow rollers don't occur very often, scientists have known about them for a long time. This 1893 article describes their appearance in a field in Ohio.

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In this case, the snow rollers appeared in and around The Nature Conservancy's Silver Creek Preserve in south-central Idaho. Sunny Healey, the preserve's manager, told Nature's Cool Green Science blog that she had never seen them before in 20 years of living on the preserve. She described the snow rollers as being about 18 inches in diameter.

When Healey first glimpsed the snow rollers from a distance, she thought they were trumpeter swans, which sometimes bunch together in the fields. On closer observation, she realized they were frozen spheres, and noticed the roll marks that they left in the snow.

Snow rollers, similar to these ones photographed in Ohio in 2014, appeared in Idaho last week.

If it's winter, it must be time for the latest Harbin Ice and Snow Festival, an annual showcase of wintry sculptures in Harbin City, in China's Heilongjiang province. Here tourists take a selfie in front of giant ice sculptures during the festival's opening night on January 5.

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This year's festival is themed "Pearl on the Crown of Ice and Snow."

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More than 1 million visitors are expected to attend the dazzling ice festival, which runs through February.

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International ice sculptors will compete for honors at the festival.

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The event offers more than 100 events, covering tourism, culture, trade, sports, and fashion.

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It always begins on January 5.

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At night, the creations are illuminated from within by LED lighting.

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A large source of the huge blocks of ice needed to make these chilly wonders is the nearby Songhua River, which yields the raw material for the sculptors.

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The sculptors then use a variety of saws, picks and chisels on the ice blocks, working long hours leading up to the festival.

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The festival's origins date to 1963, with Harbin's winter ice lantern shows, a tradition for the city.

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An ice lantern festival and an international ice sculpture expo run concurrently with the broader festival.

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