Source: AGU Advances
It is surprising how little we know about some very basic quantities, like how much ice is in the atmosphere and how it gets there. By combining numerical experiments with a global storm resolving model, aircraft measurements, and satellite observations, Atlas et al.  investigate processes regulating the ice particle concentrations in the southern ocean’s climatologically important mixed phase clouds. They find that the observed cloud properties can’t be explained without accounting for ice-multiplication processes. Ice’s proclivity to make more ice and deplete liquid limits cloudiness and buffers mixed phase clouds against aerosol perturbations. Their work further illustrates how a new generation of climate models is making it possible to quantify processes once hidden under a veil of parameterizations, and, as Hoose  points out in a companion Viewpoint, gives impetus to the need for yet more fundamental studies of ice-forming processes.
Citation: Atlas, R.L., Bretherton, C.S., Khairoutdinov, M.F., & Blossey, P.N. . Hallett-Mossop rime splintering dims cumulus clouds over the Southern Ocean: New insight from nudged global storm-resolving simulations. AGU Advances, 3, e2021AV000454. https://doi.org/10.1029/2021AV000454