In early April 2022, I was driving a car on a German motorway somewhere near the border between Hessen and Rheinland-Pfalz. The local speed limit was 100 km/h, with an additional speed limit 80 km/h bei Nässe (literally: „by wetness“), meaning when there is a layer of water on the road. It was freezing and lightly snowing at the time, but the snow did not stick to the road. I was driving around 95 km/h (like everybody else) and, when passing a static radar speed gun, saw a white flash indicative of a photograph being taken, suggesting I may have passed a speed limit and might expect a fine.
I was surprised, because air and road weren't wet; it was snowing, and I don't think snow is wet. Does traffic law enforcement consider snow as wet? There is a long discussion on this forum at verkehrsportal.de, but it seems everyone is speculating and nobody knows the answer.
During a charging break soon after the photograph was taken, I noticed that my front license plate was obscured by snow (so were all others), for which there is apparently a €5 fine — so perhaps the flash was not due to speeding but due to an obscured license plate (they can probably still tell the car through the Umweltplakat). So far, I have not received any letter for any fine.