The impact of entrainment and mixing on the fine-structure of cloud turbulence
Responsible: Theres Riechelmann
Project type: ​DFG research project within the priority programme ​MetStröm
Duration: 01/02/2012-31/09/2013

The entrainment of clear air and its mixing with cloudy air impacts the dynamics and the structure of a cloud over the whole range of spatial and temporal scales. In spite of its ultimate importance for the droplet dynamics with impact on precipitation and cloud albedo - and thus also on the atmospheric mesoscale dynamics - our understanding is rudimentary.

In this joint project, experimental and numerical investigations which cover all ranges of scales are combined for a detailed study of the entrainment and subsequent mixing in cumulus clouds. Thereby PALM is used to determine the initial conditions for direct numerical simulations of mixing layers between clear and cloudy air. The direct numerical simulations will in turn provide necessary information for subgrid-scale parametrizations of the LES. Our focus is on understanding how the entrainment and mixing and thus the strongly intermittent small-scale turbulence affects the evolution of the droplet size and number distribution. This multiscale study promises to provide the detailed quantitative data to better understand homogeneous and inhomogeneous mixing scenarios and the related time scales of phase changes.