Heads in the clouds

Fluffy simulations

By Hamish Johnston in Portland, Oregon

Have you ever wondered why clouds are fluffy?

Well, it’s not an easy question – according to Yong Wang at UCLA. Wang was here at the APS March Meeting to talk about his simulations of cumulus clouds, the fluffy ones that tend to appear after about noon on a sunny day and don’t tend to spoil the rest of the day.

Wang says that these clouds are droplets supported by thermal convection, and their shapes arise because this is a “complex non-linear system” that is driven by thermal plumes.

The simulation begins with a homogeneous layer of water droplets into which small thermal plumes rise. After a while, the jostled droplets look a lot like fluffy cumulus clouds (see above).

Wang didn’t seem to think that there were any practical applications for his work – but I would have thought this could help climate physicists understand why certain clouds form.

You can read more about Wang’s simulations here.