TRANSCRIPT
Hailstones, like the ones you're hearing now, can be bad news, especially if you have a car left out in the elements.
And it seems some parts of Australia are more prone to hail than others.
Scientists from the University of New South Wales and the Bureau of Meteorology have examined how hailstorm trends have been changing.
In the case of some heavily populated areas, not having your car undercover could be ill-advised.
Climate Change researcher Tim Raupach led the study.
"We were interested in looking at how the conditions that come together to form hailstorms, how the occurrence of those conditions has changed over the last four decades across Australia on a continental scale. And what we found was that the frequency of those conditions has decreased across quite a lot of the country, especially in southeast Queensland, but there have also been some increases, most notably over highly populated regions like Sydney, Canberra and Perth. "
Hailstones are formed when raindrops freeze after being carried into extremely cold regions of the atmosphere by thunderstorm updrafts.
And they can get larger by colliding with liquid water drops that then freeze on the surface of the hailstone.
Dr Raupach says hailstorms are difficult to measure and model.
"One thing we can say is that we can identify the atmospheric ingredient that is the most important in the changes. And the thing that's been changing that has caused these increases over the southeast and the southwest or Australia is a thing called atmospheric instability, which is the propensity of the atmosphere to form as thunderstorm. So, it seems like in those regions, the atmosphere is becoming more unstable, and therefore you're more likely to get a thunderstorm that could cause hail to form to occur. And in the other regions of Australia, especially across the north, we've seen a decrease in the instability and therefore a decrease in the hail prone conditions."
Dr Joshua Soderholm, a radar research scientist at the Bureau of Meteorology reveals the bureau's long-term weather radar archive was used to compare radar observations.
The comparison used data from 20 radar sites across the country, with records ranging from 12 to 24 years at each site.
Dr Soderholm says while the paper is not climate-related, the behaviour of hailstones in warmer environments was considered.
"We found that changes in, particularly heat in the atmosphere has been driving these trends. So, we know that that is also related to a changing climate, so you could certainly associate it with that as well."
Dr Soderholm the study draws attention to hailstorm frequency over time and will help Australia build resilience against future hail events.
"I think it just raises the awareness that how climate is changing in Australia, it's been changing over the last 40 years, and it will continue to change into the future. So, the next steps for Tim at UNSW, is to start looking at the future perspectives. So how we expect how to change into the future and how climate moderates hailstorms across Australia."
Dr Raupach agrees more research is required to determine whether these climate conditions will continue to change in the future.
"We looked at the past in this study and I'm really interested in going forward and looking into the future. And what that means is using simulations and numerical models of the weather to understand how those conditions are changing, and to try to make some projections for the future and understand the role of climate change in those changes. So, all our future work will focus on working out how the storms may change in the future in a changing climate."
As hail can cause significant damage to homes, buildings and cars, the Insurance Australia Group says it's important for Australians to protect their homes and vehicles against these impacts.
IAG’s Mark Leplastrier has these tips on how to be better prepared.
"Generally speaking, for hail prone regions Australia, there's a few things you can do. When you're thinking about doing major works on a building or building new, new homes, you can put wider eaves on houses to protect windows, you put shutters on windows to protect them. You can put things like stacking on tile roofs as well. IAG produced from hail fact sheets, which are available on our website and provide some really useful advice for consumers."
