A crack team of the world's best weather scientists, including a researcher from Australia, has travelled to South America to study extreme thunderstorms and in the process has recorded one of the largest hailstones ever found.
One hundred and sixty scientists from across the globe travelled to Central Argentina late last year to chase and study the extreme storms that regularly hit the communities on the eastern side of the Andes Mountain range.
Monash University researcher Joshua Soderholm said they were able to study a hailstone that was 11.5cm in diameter that had crashed through the roof of a woman's house in the town of Villa Carlos Paz in the Cordoba province.
"It's the largest hailstone that I've ever touched and we were quite excited to see something that large but it's catastrophic what those stones do," Dr Soderholm said.
"They can kill livestock and could kill a person if they were unlucky enough to be hit.
"It's just hard to fathom something like that just falling out of the sky."
The giant hailstone badly damaged the woman's house in a storm early last year but she collected it and kept it in her freezer.
"We were lucky enough to visit her and collect a 3D scan, so we can essentially take the hailstone home and study it," he said.
"Luckily these giant hailstones don't fall in great quantities … usually only a couple at a time."
The exciting find was made as part of a US-funded field experiment called Relampago, which is Spanish for "flash of lightning".
Dr Soderholm said Argentina was chosen because it experiences some of the most extreme thunderstorms in the world.
In a scene that resembled the movie Twister, scientists drove thousands of kilometres across Argentina chasing storms and deploying weather monitor equipment.
"We used mobile radars, weather balloons and instrumentation attached to trucks which we drove through the storms — it was an experience of a lifetime," he said.
"We definitely experienced the wild weather, particularly around the Mendoza province which is a famous wine region.
"Hail storms are prolific through that region and our group in particular intercepted two severe hail storms and we were able to measure the hail size."
Dr Soderholm said the purpose of the expedition was to better understand what causes such violent storms.
"At the moment we don't know how this giant hail actually forms in thunderstorms," he said.
"We have all these very fancy weather models which can simulate storms very accurately, even tornadoes, but we can't generate the giant hail within these models at the moment.
"We don't know the path the hail takes through the storm to grow so big, so we're trying to collect as many of these stones a possible and look at their aerodynamics, look at their weight, and try and study the storms that produce them to better understand how we get to these extremes."
The largest hailstone ever recorded was a 20cm diameter monster which fell from the sky during a severe thunderstorm in Vivian, South Dakota in the United State in July 2010.
Dr Soderholm, who graduated from the University of Queensland and has studied warm-season thunderstorms in south-east Queensland, said Australia also had its share of giant hail.
"I have heard of some 10cm stones up on the Darling Downs during the Boxing Day storms on 2016 … that's exceptional, that's very rare, we do get them but it is rarer that other places around the world," he said.
Dr Soderholm said Australia can learn much from the Relampago expedition.
"We're going to use this data so that we can better understand how these large hailstone are produced to improve our modelling of thunderstorms and our weather radar algorithms to detect giant hail," he said.ABC