Hailstone library to improve extreme weather forecasting

A University of Queensland library filled with hailstones instead of books is helping researchers better understand and predict destructive storms.

Dr Joshua Soderholm, an honorary senior research fellow at UQ’s School of Environment, and lead researcher, PhD candidate Yuzhu Lin from Penn State in the US, found that storm modelling results change significantly when using real hailstones.

The research paper is published in the Journal of Atmospheric Sciences.

“People tend to think of a hailstone as a perfect sphere, like a golf ball or a cricket ball,” says Dr. Soderholm. “But hail can have all sorts of strange shapes, from an oblong shape to a flat disk or with spikes sticking out of it – no two hailstones are the same.”

“Conventional scientific modeling of hail assumes spherical hailstones, and we wanted to know if this changed when natural, non-spherical hail shapes were used.”

Lin said they found the differences were significant.

“Modeling the more naturally shaped hail showed that it was following different paths through the storm, growing differently and landing in different places,” Lin said. “It also affected the speed and impact of the hail on the ground. This way of modeling has never been done before, so it’s exciting science.”

Dr Soderholm said creating a “hailstone library” was essential to further refine hailstorm simulations.

“It’s actually a dataset that can represent the many different shapes of hailstones, to make weather modeling more accurate,” he said.

“Our study used data from 217 hail samples, which were 3D scanned and then cut in half, to tell us more about how hailstones formed. This data is now part of a global library, as we try to get a really clear picture of the shape and structure of hailstones.”

Dr. Soderholm said the research has considerable potential. “Right now, the modeling is specifically for storm scientists, but the ultimate goal is to be able to predict in real time how big hail will be and where it will fall,” he said.

“More accurate forecasts would of course help alert the public so they can protect themselves in the event of hail and mitigate damage. But it could also significantly benefit industries such as insurance, agriculture and solar farming, all of which are susceptible to hail.”

Dr Soderholm is also a research scientist at the Australian Bureau of Meteorology. Some hail samples for the UQ dataset were provided by Higgins Storm Chasing.