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posted by Fnord666 on Friday May 01 2020, @06:47AM   Printer-friendly
from the need-a-stronger-umbrella dept.

'Gargantuan' hail in Argentina may have smashed world record:

A supercell thunderstorm pelted a city center in Argentina a few years ago with hailstones so large scientists suggested a new category to describe them — gargantuan hail.

Researchers investigating the 2018 storm found one hailstone likely measured between 7.4 and 9.3 inches across, potentially setting a new world record. The current record belongs to a hailstone that measured 8 inches across, or about the size of a volleyball, that fell near Vivian, South Dakota.

"It's incredible," said Matthew Kumjian, associate professor in the Department of Meteorology and Atmosphere Science at Penn State. "This is the extreme upper end of what you'd expect from hail."

The scientists proposed hail larger than 6 inches should be classified as gargantuan, and said more awareness of these events, while rare, could help piece together a better understanding of the dangerous storms.

"Anything larger than about a quarter in size can start putting dents into your car," Kumjian said. "In some rare cases, 6-inch hail has actually gone through roofs and multiple floors in houses. We'd like to help mitigate the impacts on life and property, to help anticipate these kinds of events."

The storm in heavily populated Villa Carlos Paz, Argentina, offered scientists a rare opportunity to study a well-documented case of gargantuan hail. As the storm unfolded, residents took to social media, posting pictures and videos.

Hail typically occurs during severe storms, which produce strong, sustained updrafts. The winds hold hailstones aloft long enough to grow in sub-zero temperatures high in the atmosphere. But predicting hail size remains challenging, the scientists said.

Journal Reference:
Matthew R. Kumjian, Rachel Gutierrez, et al. "Gargantuan Hail in Argentina", Bulletin of the American Meteorological Society Vol. 101, No. 4 (2020), DOI: https://doi.org/10.1175/BAMS-D-19-0012.1

See the PDF of the report for the full analysis. Scroll down to the end for pictures of the three largest gargantuan hail they included in their report. One of the hail stones weighed over a pound (~ 1/2 kilogram)!


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  • (Score: 2, Informative) by khallow on Friday May 01 2020, @02:52PM (6 children)

    by khallow (3766) Subscriber Badge on Friday May 01 2020, @02:52PM (#988991) Journal
    And then, they have to come up with language to describe the resulting uncertainty that all introduces.
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  • (Score: 2) by DeathMonkey on Friday May 01 2020, @05:30PM (5 children)

    by DeathMonkey (1380) on Friday May 01 2020, @05:30PM (#989059) Journal

    And then, they have to come up with language to describe the resulting uncertainty that all introduces.

    You mean like stating the size as a range? The exact thing that triggered the anti-science nutjobs in the first place?

    one hailstone likely measured between 7.4 and 9.3 inches across

    • (Score: 2, Informative) by khallow on Friday May 01 2020, @05:42PM (4 children)

      by khallow (3766) Subscriber Badge on Friday May 01 2020, @05:42PM (#989068) Journal

      You mean like stating the size as a range?

      And the use of the phrase "likely measured".

      The exact thing that triggered the anti-science nutjobs in the first place?

      I guess you could read the thread and see what was actually said.

      • (Score: 0) by Anonymous Coward on Friday May 01 2020, @07:47PM (3 children)

        by Anonymous Coward on Friday May 01 2020, @07:47PM (#989146)

        While the journalist's wording may be imprecise, it doesn't make it ambiguous at all. It obviously means that if someone had managed to measure the size of the hail stone before it shattered on impact with the ground, they would have measured it somewhere between 7.4 and 9.3 inches across. You knew what the journalist meant but chose to fuss about it anyway.

        There was photogrammetric analysis to estimate the size of the hail stone in the video. The range of 7.4 to 9.3 inches is based on a 95% confidence interval.

        And you can read the actual scientific paper [ametsoc.org] to learn about the photogrammetry and to see how the scientists actually described their analysis:

        and a hailstone photogrammetrically estimated to be between 7.4 and 9.3 inches (18.8−23.7-cm) in maximum dimension

        The scientists are actually being very precise here. Large hail stones are often not spherically shaped. They may be ellipsoids or even more irregularly shaped. Hail size isn't reported as the minimum length across the hail stone or even an average length across the hail stone. Instead, size is defined as the maximum distance from one end of the hail stone to the other end. And for irregularly shaped large hail, it's important to be precise in this manner.

        As for your statement elsewhere in this thread that the video might be a hoax, you should be ashamed for having posted something quite so utterly moronic. A few other very large hail stones from this event were actually measured. The video would certainly show the damage resulting from the hail storm, which could be assessed after the storm was over. The video was taken in an urban area and shows some of the largest hail shattering upon impact with hard surfaces on the ground. That's not surprising at all considering the likely size of the hail and resulting force of the impact. So it wouldn't have even been possible to go outside and actually measure the hail, because it smashed upon impact. And even if that didn't happen, it would be truly moronic for someone to go outside and try to collect large hail stones during the storm. That's just asking to get knocked out or killed from being hit by a massive hail stone. Of course, if they wait to go out until the hail has stopped, even if the hail didn't shatter on impact, it would have melted somewhat and they would not be measuring its size when it actually fell. Perhaps you should have read the article before posting something so moronic.

        • (Score: 1) by khallow on Friday May 01 2020, @08:14PM (2 children)

          by khallow (3766) Subscriber Badge on Friday May 01 2020, @08:14PM (#989168) Journal
          Let's use more accurate language here. I didn't fuss about the precision of the wording at all. It's fine as far as I'm concerned.
          • (Score: 0) by Anonymous Coward on Friday May 01 2020, @10:22PM (1 child)

            by Anonymous Coward on Friday May 01 2020, @10:22PM (#989239)

            We could also avoid posting misinformation that the hail measurements were a hoax. That would be a good start. Any mistake by the journalist is relatively minor compared to the misinformation you posted earlier in this thread. Had you actually looked at the journal paper, which was written by the actual scientists, it would have been very clear that they were very careful in their analysis and they weren't duped by a hoax.

            There's a difference between objecting to something that is genuinely ambiguous versus being pedantic. You're just being pedantic.

            By the way, I'm not sure it's entirely inaccurate to say that the scientists measured the size of the hail. For example, I might estimate wind speed by looking at the damage done by high winds like the size of any tree limbs that fall. And I might estimate hail size by looking out my window and visually guess the size of the hail that's falling. But that's not what happened here at all.

            There is video of the hail storm. The scientists visited the site where the video was recorded and measured other objects in the scene. By measuring other objects in the scene, they could infer the size of hail that was seen falling in the video. While this is an indirect form of measurement, I believe it probably does constitute measuring the size of the hail. There's obviously some margin of error, no doubt due to the resolution of the camera, possibly an oblong shape to the hail stone, and perhaps a bit of uncertainty about the precise location where the video was recorded. That's why a 95% confidence interval was reported.

            You asked whether other objects were used as a reference to compare the size of the hail. That's exactly what the scientists did. Now it's a bit more complicated in to determine the size of an object in a video when there may be some uncertainty about its distance from the camera. But from reading the paper, I believe it's fair to say the scientists measured the size of the hail. It's an indirect measurement, for sure, but it's not an arbitrary guess.

            Accuracy matters. And you are wrong.

            • (Score: 1) by khallow on Saturday May 02 2020, @01:01AM

              by khallow (3766) Subscriber Badge on Saturday May 02 2020, @01:01AM (#989276) Journal

              We could also avoid posting misinformation that the hail measurements were a hoax.

              I did not said it was a hoax, merely that a hoax was covered by the phrase "likely measured". When you're basing observations on video or other sources which can't be verified directly you have to accept the possibility that some or even all of it of it could be faked beyond your ability to detect. It should be SOP to consider the scenario not misinformation.