Am I referring to the COVID-19 pandemic, the relative sizes of the world’s largest mammals, or the size of the US national debt? Actually, as interesting as those topics might be, I am talking about what could be the largest hailstone ever in recorded history. This one has been called a “Gargantuan” hailstone.
Before we discuss this new find it would be good to review just how hailstones are formed in nature. The National Weather Service defines hail as “Showery precipitation in the form of irregular pellets or balls of ice more than 5 mm (millimeters) in diameter, falling from a cumulonimbus cloud.” Hail stones actually start off as raindrops. Raindrops form when moisture adheres to a dust particle or some other particulate and as moisture is attracted to the particle it forms a raindrop. A lot of what we see as rain close to the ground starts off as snow higher in the atmosphere and as it falls through warmer layers of air it melts and produces raindrops.
What we need to see is how the air flows in and out of a cumulonimbus cloud. The warm air rises into the cloud and the colder air flows down out of the cloud. This sets up the mechanism for making a hailstone. It starts out with a tiny (microscopic) dust particle or any other kind of particulate. Moisture adheres to the particle and when enough of them gather you have a raindrop. The updraft takes the drop high into the cloud past the freezing point and a layer of ice forms. Gravity takes over when the wind can’t hold the now frozen particle up any longer and it starts to fall. The particle attracts some more moisture and gets caught on another updraft which again freezes the newly attracted liquid layer. It freezes and the process continues over and over again building a bigger and bigger hailstone. The larger it gets the more times it had to be caught by the stronger updrafts. The hailstone will fall to the ground when it gets heavy enough that the updraft can no longer send it to the higher and colder layer of air.
The layers can be seen when the hailstone is sliced open. It looks like the rings on a tree that has been cut down. Each ring represents one trip to the colder air aloft. The size of a hailstone can range from a tiny hard-to-see ball, to marble-size, to golf ball-size, to baseball-size hail to the largest hailstone ever found in the U.S. that was about the size of a soccer ball.
The heaviest U.S. hailstone ever was found in Vivian, South Dakota July 23, 2010. Les Scott, a resident of this small (under 200 population) rural South Dakota town found the hailstone while he was surveying the damage the storm caused on his property. He put it and other hailstones he collected in a freezer. A six hour power failure due to the storm allowed for some minor melting of the stone. The NOAA National Weather Service Forecast Office in Aberdeen, South Dakota received reports concerning the storm and the possible tornado that struct the area. They contacted the Lyman County, South Dakota Emergency Manager Steve Manger to coordinate a damage survey. The day after the storm he met with Les Scott to see the mammoth hailstone. The size of this monster hailstone, even after some melting was amazing. It was 8 inches in diameter, weighed 1 pound 15 ounces, with a circumference of 18.62 inches. According to soccer.com the circumference of the standard soccer ball is 18-20 inches so that makes the largest U.S. hailstone roughly the size of a soccer ball. The previous record weight for a U.S. hailstone was 1.67 pounds and the stone was found in Coffeyville, Kansas in 1970. The hailstone with the largest circumference found in the U.S. was found in Aurora, Nebraska in 2010 and its circumference was 18.75 inches.
Now we come to the possible record shattering hailstone that’s being called “Gargantuan.” This hailstone fell during a 2018 storm over Villa Carlos Paz, Argentina. Residents there took pictures of the event and posted them on social media. This gave the scientists more information than they would usually obtain from one hailstorm. As explained in an April 30, 2020 article in Phys.org titled “Gargantuan hail in Argentina may have smashed world record” written by Matthew Carroll of Penn State University scientists at his university studied the multitude of pictures of hailstones and actual accounts from witnesses.
Quoting the article “Researchers followed up on the accounts a year later, interviewing witnesses, visiting sites where damage occurred, collecting photogrammetric data, and analyzing radar observations. Using photogrammetry -taking measurements from photographs – and video evidence, the scientists estimated one hailstone may have set a world record.” The two hailstones I mentioned at the beginning of this article represent the largest and second largest hailstones in the world, but this Gargantuan stone looks like it will take the title. According to Matthew Kumjian, associate professor in the Department of Meteorology and Atmosphere Science at Penn State University “It’s incredible. This is the extreme upper end of what you’d expect from hail.” From their examination this hailstone is estimated at between 7.4 inches and 9.3 inches across. That would be a new world record.
You might think that hailstorms that produce such stones would be extremely rare, but they may be more common than originally thought. According to Rachel Gutierrez, a Penn State graduate student and co-author of the scientific paper, “There typically isn’t a lot of data from storms outside the U.S. ” “Having this shows us these crazy, high-impact events can happen all over the world.” The problem is getting credible data from other parts of the world. They also want to continue their research into how these strong storms form and how they can create such large hailstones.
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