Why Are Clouds Over the Southern Ocean Super-Cool?

Abstract

When water drops below 0° Celsius, we assume it turns to ice. This is not always true though, especially inside of some clouds over the Southern Ocean. When water exists as a liquid below 0°C, it is known as super-cooled liquid water. Water only stays liquid below 0°C if it is extremely pure. Pollution and dust are two examples of impurities that can help water freeze. The water in Southern Ocean clouds has had very little contact with pollution or dust, so these clouds are often made up of super-cooled liquid water instead of ice. Super-cooled liquid water clouds reflect more sunlight back out into space than ice clouds do. Whether clouds are made of liquid or ice can control how warm the ocean is. This makes Southern Ocean clouds super cool as well as super important for the Earth’s climate!