On the evening of 13th December the temperature was dropping fast and moisture level was above 95%. It was time to go. And what an evening it turned out to be! Very good crystal material created amazing halos in the beam of a portable light or car headlight. A crystal swarm lasted typically less than 15-30 minutes at a given location and then the search for another good spot started. Later in the night I was able to enjoy a display for maybe an hour at a completely dark field. During that time I had time to lay on my back (while the camera exposure was ongoing) and absorb the amazing sight.
There are several interesting features in the photos (blue spot, the “dark loop” on top of diffuse arcs etc.). On the attached photo there is a rough draft simulation illustrating the different intensity effects. Obviously fine tuning has to be done. More photos and some text can be found here. A more detailed description will follow after I have had time to concentrate on the photos and simulations.