There's Something Different About Clouds in Antarctica, And It Could Be Important

A new study shows that the way water and ice interact in the clouds above Antarctica is different than the way water and ice interact in the ocean.

Researchers have identified a process of secondary ice production through a combination of modeling, satellite imagery and data collected from flying through the clouds. This means ice particles collide with water droplets that are supercooled, shattering them and creating many more shards of ice.

This sequence of events is referred to as Hallett-Mossop rime splintering. It reduces the amount of sunlight that is reflected back into space and allows more of it to go into the ocean below.

Atlas et al., AGU Advances, 2022.

The Southern Ocean is a massive global heat sink, but its ability to take heat from the atmosphere depends on the temperature structure of the upper ocean.

10 Watts per square meter of extra energy could reach the ocean if the clouds were at temperatures between -8 and -8.

The ice can fall into the ocean very quickly, because it is very efficient to form inside these clouds. The amount of water in the clouds is quickly reduced by that.

The shape of the clouds affects how well they protect the water underneath.

Climate models need to be weighed up in order to be as accurate as possible.

Atlas says that the ice crystals deplete much of the thinner cloud, therefore reducing the horizontal coverage.

Ice crystals deplete some of the liquid in the thick core of the cloud. The ice particles reduce the cloud cover.

At the peak of summer in February, 90 percent of the skies are covered in cloud. A quarter of the clouds covered by this study are mixed-phase clouds, so the potential effects shouldn't be underestimated.

The researchers behind the new study would like to see Hallett-Mossop rime splintering taken into account in global climate models, so that we can gain a more detailed understanding of how Earth's climate is shifting.

Climate models don't adequately account for all the different types of clouds swirling around the globe, all the different processes happening inside them, and how temperatures might be affected.

Atlas says that low clouds in the Southern Ocean shouldn't be treated as liquid clouds.

Ice formation in Southern Ocean low clouds has a significant effect on the cloud properties and needs to be accounted for in global models.

AGU Advances has published the research.