Record hail in the Queensland tropics is helping scientists better understand how destructive weather events are formed.
Key points:
- Researchers say being able to study giant hail is an incredibly rare opportunity
- Meteorological researchers hope to better understand how giant hail is created, especially in tropical climates
- Part of Yalboroo’s giant hail has been cut so scientists can examine its growth patterns
An intense storm in October last year dumped massive, spiky hail on the small town of Yalboroo, north of Mackay.
The largest stone measured 16 centimeters in diameter, the largest ever recorded in Australia.
A local managed to collect some of the stones and store them in his freezer, before they were sent to the University of Queensland in Brisbane, where they were measured, scanned and cut.
For the researchers, it was a unique opportunity, with the samples arriving in the lab “like Christmas Day”.
“It’s incredibly rare to have [hail] of this size at this latitude … when you think of the tropics and giant hail, those two things don’t usually come together,” said Bureau of Meteorology researcher Joshua Soderholm.
“We didn’t manage to get the 160mm stone, but we managed to get the 145mm one.
“It’s an incredibly rare hailstone to be able to physically examine and understand the process by which it was formed.”
Unravel the secrets of the storms
Mr Soderholm said being able to examine the composition of giant hailstones gives researchers insight into the intense systems that form them.
He said the Yalboroo hailstones reveal a lot about this rare event.
“You get a very large amount of clear ice and we know that forms when there’s a huge abundance of water in the storm,” he said.
“It’s kind of what we’d expect to see, but it’s also good to confirm as we’ve never been able to observe this for a hail of this size in Australia before.”
PhD student Kelly Cook said looking at the cross-section of the stones reveals a lot.
“What interests us is the updraft and we don’t know exactly if the growth of hailstorms is encouraged by very strong updrafts,” she said.
“We were slicing through the hail so we could find the embryo and start looking at growth rings and growth mechanisms that may be important for the development of this type of hail.
“The things I’m going to study are environmental conditions, miso-scale processes like sea breezes or topographical effects and the role they play in forming these very large hailstones.”
Josh Soderholm said it was already clear that for the stones to get as big as they did, they had to be in the storm cloud for an extended period of time.
“We’re talking beyond 20 minutes, half an hour in a way. So for it to grow that long, the storm must have evolved in a special way to sustain it,” he said. .
A rare learning opportunity
Once the hailstones were safely delivered, the team set about preserving some and scanning and cutting others.
They also scanned the hailstones to create interactive 3D images and printed some using a 3D printer.
It is hoped that this unique opportunity will lead to better severe weather modeling and forecasting.
PhD researcher Kelly Cook said data on the shape of hail and the speed of hail force are important to understand.
“It can feed back into modeling studies and radar applications and algorithms so that we can better measure and detect hail size and sink speed,” she said.
“And that can be really beneficial in mitigating the potential damage that can result from impact.”
Mr Soderholm said the warning of more frequent and intense thunderstorms in parts of Australia made this research very important.
