Study of cloud droplet formation and growth under turbulent conditions in LACIS-T

The study of cloud formation is a crucial aspect of understanding the Earth's weather and climate system. Cloud droplet formation, growth, and the resulting size distributions are influenced by various atmospheric conditions. Despite extensive research, the impact of turbulence on droplet formation and growth remains incompletely understood.

To address this knowledge gap, we investigated the effect of turbulent saturation fluctuations on these mentioned processes. The respective study was conducted using the turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T, Niedermeier et al., 2020) which is a closed-loop, moist-air wind tunnel. LACIS-T is an ideal facility for pursuing mechanistic understanding of these processes and interactions under well-defined and reproducible laboratory conditions.

In LACIS-T, by mixing of three conditioned air streams (i.e. two particle-free air streams, and one aerosol stream), it is possible to precisely adjust temperature and water vapor fields so as to achieve various (super)saturation levels. A passive or active grid are used to introduce turbulence.

In our study, we examined the growth of size-selected monodisperse NaCl particles under various conditions of saturation and temperature at different turbulence patterns. Results of the study provide new experimental insights into the effect of turbulence on cloud droplet formation, growth, and consequently, the shape of cloud droplet size distributions.

Niedermeier et al. (2020), Atmos. Meas. Tech., 13, 2015-2033, https://doi.org/10.5194/amt-13-2015-2020.

Keywords: Cloud droplet growth, Droplet size distribution, Turbulence, Saturation fluctuations