What is the recipe for a cloud? This is like asking for the recipe for curry. There are many different types of curry, and the result depends upon which spices are used and how they are combined.
For a long time, clouds over the Southern Ocean have puzzled meteorologists; there are more of them and they hang around for longer than climate models predict. Benjamin Murray and his colleagues from the University of Leeds have shown this is because of the delicate ingredients that goes into Southern Ocean clouds.
Writing in the journal PNAS, they show that the ultra-clean air in this region means there is a paucity of particles to encourage the growth of ice. So, instead of progressing through the usual cloud cycle, where particles help ice crystals to grow and fall out, Southern Ocean clouds persist as a mist of miniscule droplets, struggling to gain weight and fall from the sky.
Currently, climate models don’t include the right type of particles in their recipe for clouds and, consequently, they fail to reproduce massive areas of Southern Ocean cloud – some as big as the entire UK. This means they miscalculate the amount of heat reflected, with knock-on consequences for predicting weather and climate.
