In a two-week ACTRIS measurement campaign, 24 measuring instruments and 38 scientists from nine nations are in action.

Among them: is the Cloud Droplet Analyzer from Palas GmbH. The precise aerosol spectrometer measures the size of dust particles and, under appropriate conditions, also fog droplets and determines the water content of the air. This information is essential for weather and climate research.

The setup at the Sonnenblick Observatory in Austria was a challenge. At 3105 m altitude in sub-zero temperatures, darkness, snow, and winds of up to 100 km/h, Sergej Sel, head of the Optics and Sensor Systems Department, put the instrument into operation. But it's worth it. Researchers worldwide are obtaining a high-quality data set from this and subsequent campaigns. This will help research clouds, create and optimize weather forecasts and climate models, and answer questions about interactions between the warming and cooling of the atmosphere.

In addition to the measurement campaign, the Cloud Droplet Analyzer measures the distribution of Saharan dust transported from the desert across the Alps to Central Europe. At the exact location, an ENVI-CPC for measuring ultrafine particles and a Promo® 3000 have been used here for years. In particular, the Promo® 3000 with two sensors - one for indoor air, one for outdoor air - provides an excellent comparison between moist and dried aerosols. Among others, these results are made available as part of the Global Atmosphere Watch (GAW) for evaluating climate studies worldwide.

>>Sonnenblick Observatory: https://www.sonnblick.net/en/