A new ring-shaped wind tunnel facility to study wind-packing of snow

A new wind tunnel was designed and built at SLF. The facility is ring-shaped to simulate an infinite fetch. This is important for experiments where the observed processes have a slow time scale (minutes to hours). The wind tunnel was developed to study the formation of wind-packed snow. Wind-packing is the process whereby wind hardens the snow and forms crusts or slabs. The facility is equipped with sensors to monitor environmental parameters such as wind speed, air temperature and air humidity. A SnowMicroPen and an industrial camera allow to measure properties of the snow surface. The facility is flexible and mobile having outer dimensions of 2.3x1.3x0.5 m. Airflow is created by a model aircraft propeller and the wind speed reaches values of up to 8 m/s. First results suggest that saltation is a necessary condition for the formation of a wind slab.