Hailstone library improves predictions of damaging storms

Scientists have compiled a library of hailstones to help fine-tune hailstorm simulations and make weather forecasts more accurate.

To make calculations more simple, conventional scientific hailstorm modelling assumes all hailstones are perfectly spherical. In reality, they’re a little more complicated than that.

“Hail can be all sorts of weird shapes, from oblong to a flat disc or have spikes coming out – no two pieces of hail are the same,” says Dr Joshua Soderholm, honorary senior research fellow at University of Queensland and research scientist at the Bureau of Meteorology in Australia.

In their new study in the Journal of the Atmospheric Sciences, Soderholm and collaborators explored whether compiling a reference library of non-spherical, natural hail shapes could change the outcomes of hailstorm modelling.

“Our study used data from 217 hail samples, which were 3-D scanned and then sliced in half, to tell us more about how the hailstone formed,” says Soderholm.

“This is effectively a dataset to represent the many and varied shapes of hailstones.”

According to lead researcher Yuzhu Lin, a PhD candidate at Pennsylvania State University in the US, the differences were dramatic.

“Modelling of the more naturally shaped hail showed it took different pathways through the storm, experienced different growth and landed in different places,” she says.

“It also affected the speed and impact the hail had on the ground. This way of modelling had never been done before, so it’s exciting science.”

While the modelling is currently only used by scientists studying storms, Soderholm says the end game is to be able to predict how big hail will be and where it will fall in real-time.

“More accurate forecasts would of course warn the public so they can stay safe during hailstorms and mitigate damage,” he says.

“But it could also significantly benefit industries such as insurance, agriculture and solar farming which are all sensitive to hail.”