The frequency of hailstorms has increased by about 40% around Sydney and Perth over the last four decades, while hail activity has decreased across much of the rest of the country, new research has found.
The study’s first author, Dr Tim Raupach of the Climate Change Research Centre, said increases in hail frequency over Sydney, Canberra and Perth were mostly driven by atmospheric instability, which is determined by temperature and moisture.“If the atmosphere is not … stable it’s prone to form updrafts,” Raupach said. Updrafts result in warm surface air being pushed up higher into the atmosphere. “It’s more buoyant than the cooler air and it starts to rise like a hot air balloon.
A decrease in wind shear across Australia’s mid-north over the four decades corresponded with a reduced frequency of hail-prone days, the researchers found. “That climatic region – we’ve seen it in the trends starting to shift farther south. One explanation could be due to climate change.” Raupach said further research using climate projections was needed to determine how hail trends may change in the future with global heating.