Abstract. Beyond its physical importance in both fundamental and climate research, atmospheric icing is considered as a severe operational condition in many engineering applications like aviation, electrical power transmission and wind-energy production. To reproduce such icing conditions in a laboratory environment, icing wind tunnels are frequently used. In this paper, a comprehensive overview on the design, construction and commissioning of the Braunschweig Icing Wind Tunnel is given. The tunnel features a test section of 0.5 m × 0.5 m with peak velocities of up to 40 m s−1. The static air temperature ranges from −25 to +30 ∘C. Supercooled droplet icing with liquid water contents up to 3 g m−3 can be reproduced. The unique aspect of this facility is the combination of an icing tunnel with a cloud chamber system for making ice particles. These ice particles are more realistic in shape and density than those usually used for mixed phase and ice crystal icing experiments. Ice water contents up to 20 g m−3 can be generated. We further show how current state-of-the-art measurement techniques for particle sizing are performed on ice particles. The data are compared to those of in-flight measurements in mesoscale convective cloud systems in tropical regions. Finally, some applications of the icing wind tunnel are presented.

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A replication technique has been developped to study the microstructure of atmospheric ice based on the use of nail varnish rather than more harmful materials. The potential of the technique was demonstrated by obtaining and reporting microstructures for impact ice grown on metal surfaces in an icing tunnel under a range of cloud conditions. The technique reveals grain structure, growth striations, porosity and etch features which may indicate an aspect of crystalographic orientations.

Abstract. Beyond its physical importance in both fundamental and climate research, atmospheric icing is considered as a severe operational condition in many engineering applications like aviation, electrical power transmission and wind-energy production. To reproduce such icing conditions in a laboratory environment, icing wind tunnels are frequently used. Creating and maintaining a stable icing cloud in the tunnel test section yields different design constraints compared to conventional wind tunnels. In this paper, a comprehensive overview on the design, construction and commissioning of the Braunschweig 5 icing wind tunnel is given. The tunnel features a test section of 0.5m × 0.5m with peak velocities of up to 40m/s. The static temperature ranges from -25• C to +30• C. Supercooled droplet icing with liquid water contents up to 3 g/m 3 can be reproduced. Outstanding ability of the tunnel is to simulate ice crystal icing with natural ice crystals for ice water contents up to 20 g/m 3 . We further show, how current state-of-the-art measurement techniques for particle sizing perform on ice crystals. The data is compared to those of in-flight measurements in mesoscale convective cloud systems in tropical regions. Finally, some 10 applications of the icing wind tunnel are mentioned.