The Leipzig Aerosol Cloud Interaction Simulator (LACIS) is a unique facility to study aerosol particle and cloud interactions. It allows the investigation of processes such as particle hygroscopic growth, activation, and ice formation.

LACIS consists of laminar flow tube with thermostated walls. The length of the flow tube can vary from 0.5 up to 8 m, depending on the desired time scales for different experiments. Thermodynamic conditions inside LACIS are controlled with extremely high accuracy. LACIS can be operated under both, sub-saturated and super-saturated conditions. Relative humidities up to 99.5% (sub-saturated) and super-saturations down to 0.1% can be adjusted reproducibly. Up to now, LACIS has been used to study hygroscopic particle growth under sub-saturated conditions, particle/droplet growth under super-saturated conditions, the activation of lab-generated and ambient aerosol particles, and to perform a CCN closure. Sample results from these investigations will be presented.