The effect of coherent stirring on the advection–condensation of water vapour

Jacques Vanneste, Yue-Kin Tsang

Research output: Contribution to journalArticlepeer-review


Atmospheric water vapour is an essential ingredient of weather and climate. Key features of its distribution can be represented by kinematic models which treat it as a passive scalar advected by a prescribed flow and reacting through condensation. Condensation acts as a sink that maintains specific humidity below a prescribed, space-dependent saturation value. In order to investigate how the interplay between large-scale advection, small-scale turbulence and condensation controls the moisture distribution, we develop simple kinematic models which combine a single circulating flow with a Brownian-motion representation of turbulence. We first study the drying mechanism of a water-vapour anomaly released inside a vortex at an initial time. Next, we consider a cellular flow with a moisture source at a boundary. The statistically steady state attained shows features reminiscent of the Hadley cell such as boundary layers, a region of intense precipitation and a relative humidity minimum. Explicit results provide a detailed characterisation of these features in the limit of strong flow.
Original languageEnglish
Number of pages25
JournalProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Issue number2202
Publication statusPublished - 28 Jun 2017


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