Fallout from the Russian fireball encircled Earth, research shows
The meteor that exploded near Chelyabinsk, Russia on February 15 created a mushroom cloud of microscopic dust grains that spread across the sky, encircling the planet within four days.
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"Nick and Didier [Rault, another co-author] came to me and said, 'Something's wrong with the model,' " says Newman, who had designed the atmospheric model. "I said, 'Let me look at it." He went back to Gorkavyi and Dr. Rault and said, " 'It had to be at a higher altitude.' And then Nick and Didier came back and said, 'Oh, yeah, well, we know from all the photographs and all the video from the ground that the plume quickly rose up like a mushroom cloud, rose up, rose up, to 35 kilometers.' And I said, 'Well, that's the answer: That's why it drove around so fast. The winds at higher altitude are a lot faster than winds at lower altitude."Skip to next paragraph
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The "mushroom cloud" had lofted the particles into the Polar-Night Jet, the winter season (hence "polar night") high-altitude stream of air that whizzes from west to east at "a couple hundred miles per hour," says Newman. But the Polar-Night Jet is thousands of feet higher than the initial explosion, which is why he hadn't taken it into account in the initial modeling.
That's how the dust layer managed to surround the entire planet, Newman says. The high-altitude winds "lapped" the low-altitude winds. "That's where you get the snake-uncoiling effect, where the head of the snake catches up with the tail," Newman says, describing the image above. "Because at higher altitudes, winds are faster."
Play along at home
You can create your own model of micro-fine atmospheric dispersal. All you need is a bag of flour and a smooth surface. A table or hardwood floor would work, but we strongly recommend a driveway or sidewalk to minimize cleanup and/or getting in trouble. Reach into the bag and take out a big handful of flour. Throw it like a baseball and watch what happens.
You'll first notice how much of the flour doesn't fall at all, but just hangs in the air, getting tossed around by any passing breeze. Some will actually blow upwards, in defiance of gravity, if caught by a puff of air. (When I tried it, I thought the air was perfectly still, but the tiniest of breezes was still enough to throw around the cloud of flour dust I'd created.) Once all the airborne flour has blown away or clung to a nearby surface (tree, car, clothes), look down at the ground and see how much of the initial handful of flour did fall, while you were distracted by the airborne cloud. You'll see hundreds of tiny little white impacts spreading out along the direction of your intended trajectory, just like the thousands or millions of meteorite fragments that spread along 60 miles of the ground near Chelyabinsk.
When it entered Earth's atmosphere at about 42,000 miles per hour, the meteor measured 60 feet in diameter and weighed about 12,000 tons. It exploded near Chelyabinsk on February 15, 2013 at 9:20 a.m. local time, with an energy release equivalent to more than 30 Hiroshima atomic weapons. The blast shattered windows across the region, including some in Gorkavyi's parents' home.
"In Chelyabinsk, this is event of century," says Gorkavyi.
He missed seeing it live in his hometown, "but I catch it from the other side," he said, "from space."
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