Australian Weather Calendar: February 2020

February photograph by Mal Brewitt

Window to the sky

When this is the view from your apartment, armchair storm chasing is easy! Such was the case for Mal Brewitt, who was living in the Brisbane riverside suburb of Hamilton, and had been tracking severe storms forecast to hit the city. 'As they were building up in the west, I set up my equipment on my back deck and waited for them to come through. Fortunately, on this occasion the storm came right across the CBD, so I was able to watch it unfold throughout the afternoon.' Mal says while he was in the right place at the right time on this occasion, with lightning there's always an element of luck. 'That afternoon I took maybe 400 photos and there were five or six that were really good.' He says while southeast Queensland is renowned for its summer storms, it's rare to get lightning right over Brisbane city 'This was a particularly good storm, lots of lightning and to capture the city in the background was incredible.' While weather photography is a relatively new hobby for him, Mal says he'll often check the weather radars to see if big storms are developing, but 'I'm not the sort of photographer that will travel to see a storm.' When you have these kinds of displays on your doorstep, who needs to?!

The science

Within a developing thunderstorm cloud (cumulonimbus), there are millions of tiny ice crystals and super-cooled water droplets rubbing up against each other as they move up and down. This causes a positive charge to develop at the top of the cloud and a negative charge at the bottom. The negative charge at the bottom of the cloud moves closer to the ground through a faint, negatively charged channel in a series of steps called ‘leaders’, while coming up from the ground are a series of positively charged channels known as ‘streamers’. When one of the negative leaders connects with the positive streamer, a powerful electrical current races from the cloud to the ground—and this is when we see the lightning bolt. Lightning heats the air around it to a temperature of approximately 30 000 °C, which is hotter than the surface of the Sun!