Microphysical timescales and local supersaturation balance at a warm cloud top boundary
- 1 June 2022
- journal article
- research article
- Published by AIP Publishing in Physics of Fluids
- Vol. 34 (6), 067103
- https://doi.org/10.1063/5.0090664
Abstract
Recent results have shown that there is an acceleration in the spread of the size distribution of droplet populations in the region bordering the cloud and undersaturated ambient. We have analyzed the supersaturation balance in this region, which is typically a highly intermittent shearless turbulent mixing layer, under a condition where there is no mean updraft. We have investigated the evolution of the cloud–clear air interface and of the droplets therein via direct numerical simulations. We have compared horizontal averages of the phase relaxation, evaporation, reaction, and condensation times within the cloud–clear air interface for the size distributions of the initial monodispersed and polydisperse droplets. For the monodisperse population, a clustering of the values of the reaction, phase, and evaporation times, that is around 20–30 s, is observed in the central area of the mixing layer, just before the location where the maximum value of the supersaturation turbulent flux occurs. This clustering of values is similar for the polydisperse population but also includes the condensation time. The mismatch between the time derivative of the supersaturation and the condensation term in the interfacial mixing layer is correlated with the planar covariance of the horizontal longitudinal velocity derivatives of the carrier air flow and the supersaturation field, thus suggesting that a quasi-linear relationship may exist between these quantities.Funding Information
- H2020 Marie Skłodowska-Curie Actions (GA 675675)
- SCAI - HPC Cineca (HP10CA2ZRB)
- Politecnico di Torino (HPC@POLITO | HACTAR)
This publication has 46 references indexed in Scilit:
- Statistics of Small-Scale Velocity Fluctuations and Internal Intermittency in Marine Stratocumulus CloudsJournal of the Atmospheric Sciences, 2010
- Sufficient condition for Gaussian departure in turbulencePhysical Review E, 2008
- Observations of Small-Scale Turbulence and Energy Dissipation Rates in the Cloudy Boundary LayerJournal of the Atmospheric Sciences, 2006
- Numerical experiments on the intermediate asymptotics of shear-free turbulent transport and diffusionJournal of Fluid Mechanics, 2006
- A new technique for a parallel dealiased pseudospectral Navier–Stokes codeComputer Physics Communications, 2001
- Statistical mechanical description and modelling of turbulent collision of inertial particlesJournal of Fluid Mechanics, 2000
- Direct numerical simulation and subgrid analysis of a transitional droplet laden mixing layerPhysics of Fluids, 2000
- The shearless turbulence mixing layerJournal of Fluid Mechanics, 1989
- The nuclei of natural cloud formation part II: The supersaturation in natural clouds and the variation of cloud droplet concentrationPure and Applied Geophysics, 1959
- The Growth of Cloud Drops by Condensation. I. General CharacteristicsAustralian Journal of Chemistry, 1952