Atmospheric rivers

Although they've been around for millennia, atmospheric rivers were only discovered by humans during the past 25 years.

- By Dr Karl Kruszelnicki

In February 2022, one dumped cubic kilometres of water onto the city of Brisbane. An atmospheric river is a narrow, fast-flowing stream of moist air. It can be many thousands of kilometres long, and a few hundred wide. It's a giant and invisible conveyor belt of water in the sky, moving above and across the planet.

At any given moment, there are about a dozen of these atmospheric phenomena across the globe - most of them over water. But, unlike a land-based river, they are not fixed in location. Instead, they continually form, fade, reform and evolve. So they come and go.