Destructive storm hit Spain in 2022, dropping large hailstones up to 12 centimeters in diameter
Tomeu Rigo Rivas
A dental clinic scanner has produced high-resolution 3D images of the internal structure of a large calabash stone for the first time. Such a detailed view could help researchers better predict which storms produce these destructive ice chips.
“The first results are impressive,” said Carme Farnell Burke of Spain’s Catalan Meteorological Agency. “Wow! You can see inside the stone without breaking it. You could see the different layers with different densities.”
Hail during a severe storm that hit northeastern Spain in 2022 killed one child, injured dozens and caused millions of dollars worth of damage. The largest hailstone that fell was 12 centimeters in diameter, about twice the size of a tennis ball.
A few days after the storm, Farnell Burke and her co-workers went around asking if anyone had stored any hail. They collected 14 hailstones up to 8.5 centimeters in diameter that people had stored in plastic bags in the freezer.
Hailstones form when a layer of supercooled water accumulates on top of the initial ice particles of a storm. The shape and density of these ice layers within the hailstones can reveal details about the growth process. But researchers are usually only able to study a few cross-sections of a single hailstone by cutting through the ice with a hot knife.
In this case, Farnell Burke’s orthodontist friend suggested the researchers use a CT scanner instead to reveal the complete internal structure of the calabash. And scanners were available at dental clinics.
The researchers scanned three pieces of hailstone, producing hundreds of cross-sections showing the variation in density within each ice flake. Some of the details were amazing. For example, hailstones were spherical, but their cores were located far from the center. Farnell Burke said this suggests that the thickest part of the stone formed during fall, rather than when it was circulating between different altitudes on updrafts in a storm. It says that there are.
Julian Brimelow of Canada’s Northern Hail Project said several other small hailstones have been scanned this way, but the stones from Spain are much larger. “This is important because it’s still not clear where and how hail grows and reaches such impressive sizes in thunderstorms,” he says.
This increased understanding could improve predictions of hail size in future storms. “Each layer of growth can be correlated with radar data on the development of thunderstorms,” says Tomeu Rigo of the Catalan Meteorological Agency. “Then we can correlate this with new thunderstorms and project the results into the future.”
“We probably need to study more hailstones,” said John Allen of Central Michigan University, who is planning a large-scale hailstone survey in the U.S. Great Plains in 2025. It’s about how viable it is.” A lot of stones? ”
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