Abstract
Abstract. The interactions between turbulence and cloud microphysical processes have been investigated primarily through numerical simulation and field measurements over the last 10 years. However, only in the laboratory we can be confident in our knowledge of initial and boundary conditions and are able to measure under statistically stationary and repeatable conditions. In the scope of this paper, we present a unique turbulent moist-air wind tunnel, called the Turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T) which has been developed at TROPOS in order to study cloud physical processes in general and interactions between turbulence and cloud microphysical processes in particular. The investigations take place under well-defined and reproducible turbulent and thermodynamic conditions covering the temperature range of warm, mixed-phase and cold clouds (25∘C>T>-40∘C). The continuous-flow design of the facility allows for the investigation of processes occurring on small temporal (up to a few seconds) and spatial scales (micrometer to meter scale) and with a Lagrangian perspective. The here-presented experimental studies using LACIS-T are accompanied and complemented by computational fluid dynamics (CFD) simulations which help us to design experiments as well as to interpret experimental results. In this paper, we will present the fundamental operating principle of LACIS-T, the numerical model, and results concerning the thermodynamic and flow conditions prevailing inside the wind tunnel, combining both characterization measurements and numerical simulations. Finally, the first results are depicted from deliquescence and hygroscopic growth as well as droplet activation and growth experiments. We observe clear indications of the effect of turbulence on the investigated microphysical processes.
Highlights
Clouds are important players in both weather and climate
In the scope of this paper, we introduce a turbulent moistair wind tunnel, called LACIS-T (Turbulent Leipzig Aerosol Cloud Interaction Simulator), which has been developed at TROPOS in order to study cloud physical processes in general and interactions between turbulence and cloud microphysical processes, such as droplet and ice crystal formation, in particular
Laboratory experiments can provide scenarios for which physical theory and models can be directly compared to an experiment, with known initial and boundary conditions (Stratmann et al, 2009)
Summary
Clouds are important players in both weather and climate. They are the source of precipitation and significantly contribute to the radiative budget of the Earth (Lamb and Verlinde, 2011). Atmospheric clouds are often nonstationary, inhomogeneous, intermittent, and cover an enormous range of spatial (micrometers to hundreds of kilometers) and temporal (microseconds to hours and days) scales with cross-scale interactions between turbulent fluid dynamics and cloud microphysical processes influencing cloud behavior and cloud development (Bodenschatz et al, 2010).
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