Chesterton Tribune



Huge ice chunk falls from sky, crater's Liberty mans front lawn

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Dennis Nover came uncomfortably close on Sunday to being squashed flat in his front own yard, possibly by a meteorological anomaly so rare and weird that many meteorologists havent even heard of it.

At around 6 p.m., under clear skies, Nover was walking his dogs outside his home on Yorktown Street in Liberty Township when he heard a whoosh and a thud--a thud concussive enough to shake his neighbors house.

Then he saw it, a bare 30 feet away, in the lawn next to his driveway: a clear chunk of ice, basketball-sized and weighing some 15 to 20 pounds, shattered in a crater more than a foot deep and two feet wide. My dogs started barking at it, Nover said.

Nover did two things on Monday: he took a piece of the ice to Valparaiso Universitys Department of Meteorology, where no one knew quite what to do with it.

And he visited the Chesterton Tribune, where a reporter knew exactly what to do: Google clear chunks of ice falling from the sky.

The top result: a Wikipedia article entitled Megacryometeor.

Turns out, perilously large projectiles of ice dropping out of sunny skies are a thing now. Not blue ice, mind you, like the release from an airliners chemical toilet. Clear ice, like hail but not hail, inasmuch as the largest hailstone on record in the U.S.--recovered in July 2010 in Vivian, S.D.--was the size of a mere honeydew melon and weighed a puny 1.93 pounds.

The term megacryometeor was originally coined by a Spanish geologist, Jesus Martinez-Frias, after a 4.5-pound piece of ice crash-landed on a cars windshield in Tocina, Spain in 2000. That fall was followed by several others in the area over a period of a week. Since then--according to Wikipedia--at least 20 similar ice falls have been reported around the world (21, counting Novers), including a 200-pound monster in Oakland, Calif., and a 400-pound behemoth in Brazil.

Summarizing 10 years of research conducted by his team, in a 2010 article, Martinez-Frias was better able to say what megacryometeors are not than what they are. Megacryometeors are not the classical big hailstones, ice from aircrafts (waste water or tank leakage), nor the simple result of icing processes at high altitudes. A detailed historical review of such ice fall events confirms that there are many documented references of large blocks of ice which go back to the first half of the 19th century (previous to the invention of aircrafts). It also reveals that, mainly after 1950, the number of megacryometeor hits has spectacularly increased.

That increase in the incidence of megacryometeors could conceivably be related to climate change, Martinez-Frias speculated. But the actual cause of the phenomenon itself remains a mystery. (M)uch work is still needed, he urged, as no geophysical model is able to satisfactorily explain what factors cause the ice nucleation and growth, or how these unusually large ice blocks can actually be formed and maintained in the atmosphere.

That last question in particular is a baffler, because normal hailstones are formed when thunderstorm updrafts lift water droplets in the sky above the freezing level, where they become tiny balls of ice dancing in the air, growing incrementally larger as more water freezes onto them, until their sheer weight causes them to fall to earth. As Megan Dodson, a meteorologist at the National Oceanic and Atmospheric Administrations South Bend station, told the Tribune, updrafts in the Great Plains are often sufficiently powerful to keep the frozen water droplets aloft long enough to form very large hailstones: golfball- or baseball-sized. Here in Indiana, however, updrafts tend to be weaker and hailstones are typically the size of peas.

But Dodson--who cheerfully admits that, until contacted by the Trib, shed never heard of megacryometeors--knows of no updraft capable of overcoming the tremendous force of gravity which would be exerted on a quarter-ton ice cube in the troposphere, much less on Novers 15-pounder. In any case, she said, hailstones are specifically formed in thunderstorms, not in the placid Liberty Township sky early Sunday evening.

Dodson added that megacryometeors are totally cool and--if a megacryometeor it truly was--that Mr. Novers both lucky to have seen one and lucky not to have been killed by it.

There is, on the other hand, a more prosaic explanation: Novers ice fall was simply an artifact of aviation icing. Thats the best guess of Craig Clark, an associate professor of meteorology at VU, who late on Wednesday told the Trib that hes pretty confident that the ice fell off a plane. Different kinds of ice form on the exterior of aircraft under different meteorological conditions, but the prerequisite is the presence in the air of supercooled liquid water, and sometimes the ice so formed breaks off a plane in midair.

Certainly the proliferation of commercial flight after World War II could account for at least part of the spectacular increase in reported ice falls since 1950 cited by Martinez-Frias. But aviation icing cant account for any megacryometeors recorded prior to Kitty Hawk.

When Nover last spoke to the Trib, he was on his way to the Porter County Health Department, in the hope of having a specimen of his ice fall chemically analyzed. The actual source, of course--meteorological or aeronautic--wouldnt have mattered a lick if Noverd been beaned. It sounded like a whoosh. I just thought it was the wind in the trees. If that thing had hit me, it would have taken my head off.



Posted 10/11/2018




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