An ocean current hundreds of kilometers wide lives its own life, fed by energy from tiny eddies. Something similar happens in the atmosphere: small swirls pass their power on to huge air currents. This process, the inverse energy cascade, has been known for a long time. But until now, it was studied assuming the air was completely dry, as if clouds never existed.
New research adds water and phase transitions, evaporation and condensation, to the picture. It turns out that in moisture-saturated zones, the situation changes dramatically. Where the air is soaked with water like a sponge, the transfer of energy to large structures slows down. The reason lies in the clouds themselves. At their boundaries, nonlinear waves arise: warm air shoots upward, cold air plunges downward. These vertical flows act like invisible walls, redistributing energy in their own way.
The authors built a numerical model where the atmosphere is filled with vapor and droplets, and cloud microphysics works instantaneously. They found that in regions dominated by moist vortices, statistical links between cloud boundaries, vertical flows, and vorticity become key. It's like a layered cake: each layer is a phase of water, and at the interfaces between layers, powerful motions are born that set the tone for the whole energy kitchen.
The inverse energy cascade in the atmosphere resembles a financial crisis: small problems accumulate and suddenly bring down the whole system, only here energy doesn't destroy but builds giant air currents.
In Andy Weir's novel "The Martian," precise accounting for humidity and water phase transitions becomes a matter of life and death — much like in this work, where the fate of atmospheric vortices depends on humidity.