Back in May I discovered that hail storms were hazardous and perhaps becoming more so. The post that resulted is full of information about hail and, as usual, provides sources where more can be found. Even if you aren't interested in hail, you will be if you read that post - "Hail Storms- Something Else to Worry About."
Why now in the fall am I again writing about hail? It is because, here in London, there are people involved in The Northern Hail Project. That involvement has even attracted the attention of the New York Times which recently wrote about it. Given that Mulcahy's Miscellany has inadvertently become a repository of a considerable amount of hard-to-come-by hail information, I may as well provide some more.
Having already invested more time in this meteorological event than intended I will simply provide the links to the sources along with some of the information contained within them. Just as hailstones melt, links have a tendency to rot.
Here is the story about the folks up at Western who found some very large hailstones. "Northern Hail Project Recovers Record-breaking Hailstone: Rare Giant Specimen Aids Better Understanding of Hailstorms,"By Jeff Renaud, Western News, August 03, 2022.
"A Canadian record-breaking hailstone was recovered by Western University’s Northern Hail Project (NHP) field team, following a storm earlier this week near Markerville, Alta. The record-breaker weighs 292.71 grams, eclipsing the previous title holder – a hailstone weighing 290 grams, collected nearly 50 years ago in Cedoux, Sask. on July 31, 1973.
With a diameter of 123 millimetres, the hailstone has a slightly larger span than a standard DVD (120 mm).
Led by Francis Lavigne-Theriault, the NHP field team followed a storm to Markerville (about 35 kilometers southwest of Red Deer, Alta.) and found several baseball-sized hailstones.
The team traveled farther south and approximately 20 minutes after the storm had passed (6:14 pm MDT) and recovered several larger hailstones under a tree canopy, many of which are grapefruit to softball-size including the record breaker.
Lavigne-Theriault and the team ultimately collected seven bags at the aforementioned location, all of which are baseball-sized hail or larger (at least 70 millimetres or 2.75 inches in diameter). The samples are currently being stored in a freezer....
“Finding large hailstones like this is like hitting the jackpot so this Markerville sample joins an elite club of giant hailstones,” said Brimelow. “This stone will also help us refine our estimate of just how large it is possible for hail to grow.”Because giant hailstones are so rare, the international research community does not have a good understanding yet of what conditions are required for hailstorms to produce them.
“Every new data point helps inform us on what conditions are required,” said Brimelow. “Once we have measured and 3D-scanned the Markerville hailstone, we can then make thin sections. The growth layers evident in those will reveal information on the hailstone’s growth history in the storm.”
Here is the story as reported in the New York Times. Some content is provided since it is found behind the NYT's paywall.
"The Hunt for Big Hail: Hailstones of Record Size are Falling Left and Right, and Hailstorm Damage is Growing. But There is Surprisingly Little Research to Explain Why,"
By Oliver Whang ,Sept. 5, 2022
"In August, a couple of days before his 68th birthday, Leslie Scott, a cattle rancher in Vivian, S.D., went to the post office, where he received some bad news. His world record had been broken, the clerk told him. That is, the hailstone Mr. Scott collected in 2010, which measured eight inches across and weighed nearly two pounds, was no longer the largest ever recorded. Some people in Canada had found a bigger one, the clerk said.
“I was sad all over the weekend,” Mr. Scott said, a few days after he heard the news. “I’ve been telling everybody that my record was broke.”
Fortunately for Mr. Scott, this was not quite right. On Aug. 1, a team of scientists from Western University in London, Ontario, collected a giant hailstone while chasing a storm in Alberta, about 75 miles north of Calgary. The hailstone measured five inches across and weighed a little more than half a pound — half the size and one-quarter the heft of Mr. Scott’s. So it was not a world record, but a Canadian one.
The Canadian hailstone added to the list of regional records set in the past couple of years, including Alabama’s in 2018 (5.38 inches long, 0.612 pounds), Colorado’s in 2019 (4.83 inches, 0.53 pounds) and Africa’s in 2020 (around seven inches long, weight unknown). Australia set a national record in 2020, then set it again in 2021. Texas’ record was set in 2021. In 2018, a storm in Argentina produced stones so big that a new class of hail was introduced: gargantuan. Larger than a honeydew melon....Julian Brimelow, the director of the Northern Hail Project, a new collaboration among Canadian organizations to study hail, whose team found the record hailstone in August, said, “It’s a pretty exciting time to be doing hail research.”Most reports of record hail are made by civilians, but the accuracy is often lacking. The first thing most people do when they find a big hailstone? Take a picture. Second? Show it to their family or friends. Third? Put it in the freezer — where sublimation, the phase change from solid ice to water vapor, can shrink the hailstone over time.
Mr. Scott, in Vivian, kept his world record in the freezer for weeks before someone from the National Weather Service was able to officially measure and weigh it. During that time, it shrank by about three inches, he said. “I just didn’t realize what I had,” he said. “There’s a lot more hailstones that fell, and there were bigger ones than the one I picked up...."
“Hail data are terrible,” Dr. Brimelow said. “It is probably one of the worst data sets on the planet..."
The record hailstone in Canada was collected when the Northern Hail Project intercepted a supercell as it was passing through central Alberta. The researchers used radar forecasting to predict the storm’s path, then pulled up to a stretch of road around 20 minutes after the hail swath had passed. The ground was littered with baseball-size hailstones, the largest of which the researchers bagged and froze.
The biggest hailstones “are really more of an academic interest,” Dr. Brimelow said, because they “fall in such low concentrations that they’re not really as hazardous as golf-ball-size hail.” But, Dr. Kumjian said, looking for “the absolute worst-case scenario” can refine forecasting models and help explain supercell dynamics. Studying single hailstones over time can have an outsize effect on the understanding of storms. And, he said, there is the irresistible question, What is the limit of nature?
Dr. Kumjian and Dr. Brimelow have been creating a database of the largest hailstones recorded around the world. The two believe they have determined the maximum possible size of hail: just over three pounds and around a foot in diameter. They will present their findings in September at the second-ever North American hail research workshop in Boulder, Colo.
Francis Lavigne-Theriault, who coordinates storm chases and field operations for the Northern Hail Project, said the presence of large hail in central Alberta indicated that it probably occurs “a lot more frequently” than previously thought. Dr. Brimelow said that the record was “quite remarkable,” because the conditions for hail formation in the area were generally less “juicy” than other areas in the country."
Sources:
Post Script:
I won't carry on about pluviculture. In the NYT article there is mention of using cloud seeding to help decrease the size of hailstones. These days we generally think of cloud seeding as a way to increase rain and snowfall. See the Wikipedia entries for "Cloud Seeding" and "Rainmaking" and this recent Washington Post article: "Cloud Seeding Gains Steam As West Faces Worsening Droughts," Maddie Stone, Nov. 21, 2021.
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