Fog turned into diamond dust in an optimal range of -5 to -10° C. I photographed the display in the evening soon after dark, the first photo was taken 16:17. The fog lasted whole night and no doubt the show would have continued whole night too were not the guns shut down soon after 17h, finishing the party before it had even got going. Had there been until morning to play, I am sure wondrous things would have been possible. Actually, there would have been three more nights, as fog continued envelop the city pretty much constantly for three more days and nights.
In the image above — and less clearly in the one below — it looks as if instead of "subanthelic 46° supralateral arc" there is more a "subanthelic cza". If so, that would be just a segment of sub-Kern, but it has an unusual location as we are used for sub-Kerns placing most of their weight at lateral locations with an intensity minimum directly above the subanthelic point. Simulations offer a solution, however: if, instead of plate oriented crystals, Parry oriented crystals of triangularish shape are used, a sub-Kern segment is born that is centered over the subanthelic point and looks like a kind of "subanthelic cza". Allow the crystals to rotate a bit and a halo segment much in the liking of what appears to appear in the photo is formed. As a rudimentary demonstration, below are further simulations with increasing rotation of the column shaped triangularish crystals, showing how the sub-Kern turns into a "subanthelic 46° supralateral arc" (ray numbers have been increased with increasing rotation to keep simulations of roughly the same intensity). Parameter file is given at the bottom.