FIVE THINGS ABOUT FIRE IN AUSTRALIA

Australia’s recent fire season was so extreme it altered large-scale wind patterns in the stratosphere more than 16 km overhead, which normally isn’t affected by events on Earth’s surface, a new study has found. Here’s some detail.

1 SOUNDS LIKE AN APOCALYPSE

This never-before-seen behaviour can be traced to violent, fire-induced thunderclouds that formed above active fire zones in southeastern Australia. These “pyro-cumulonimbus” events, or pyrocbs, injected enormous plumes of smoke into the lower stratosphere. One plume circumnavigated the globe while rising to an unprecedented height of 30 km and spun up its own winds, which circled counterclockwise around the plume at 50 kph for more than two months.

2 CLOUDY DAYS

Southeastern Australia was in an extreme fire season in late December when strong winds caused fires to explosively intensify and trigger an outbreak of pyro-cumulonimbus clouds. At least 18 fire-induced thunderheads formed between Dec. 29 and Jan. 4, pouring smoke into the stratosphere.

3 AEROSOLS UP HIGH

These plumes confirm a key prediction about how fires generated by nuclear bomb blasts would impact the atmosphere. Fire-induced thunderclouds act like chimneys, shooting plumes of smoke filled with aerosols into the stratosphere like a volcanic eruption. Once in the stratosphere, that smoke can travel around the world.

4 REMEMBER OZONE HOLES?

A plume effectively creates a small ozone hole by lofting a pocket of ozone-depleted air into the stratosphere and preventing the two air masses mixing. Estimates suggest Australia’s pyrocb outbreak injected almost a million tons of aerosols into the stratosphere.

5 CONTINENT-SIZE CLOUD

Scientists tracked several distinct smoke plumes from Australia, including one almost 1,000 km wide and five km thick. It rose within the stratosphere over six weeks, climbing higher and faster than any pyrocb plume documented and peaking at an altitude of 32 km.