Snow Motion in the Field

A camp of seven ice-fishing tents is set up in the Davoser Alps at night to surround a line of powerful floodlight illumination panels. The tents host sixteen high-resolution cameras on arrays, carefully aligned to overlap a 100MP millimetric resolution in a thirty-meter diameter semi-circular arc configuration. The floodlight panels are retrofitted with custom-made cylindrical lenses and illuminate individual snowflakes inside a gigantic ghost-like bonfire of a thousand cubic meters in volume. This cinematographic field setup grants the filming of millions of snow particles falling together in slow motion and will shed new light on the three-dimensional clustering dynamics of snow in the turbulent atmosphere. The image is taken with the onboard camera of a small DJI Mavic drone; a similar but larger drone is utilized to calibrate this large-scale snow-tracking setup. The picture reveals an aerial view facing into the Flüelapass during operation; the excess illumination lights up its surroundings, casting extending shadows into the enchanting alpine landscape. Determined in this large-scale ambitious field imaging deployment, it reminds us of the smallness of our humble presence facing the full extent of the alpine night skies.

This work is performed in the group of Prof. Filippo Coletti at the Institute of Fluid Dynamics (ETH Zurich) and under the support of Prof. Michael Lehning at the Institute for Snow and Avalanche Research (WSL-SLF). Special credit goes out to Rafael Bölsterli (drone pilot) and support during deployment by Pim Bullee, and Yifan Wang.