The diamond dust season began in Rovaniemi on the night of 1/2 November with three snow guns running in the ski jump. Here is one of the displays photographed that night. It is noteworthy that the crystals have cavities in their ends and yet the halos requiring basal faces are strong.
Very good quality crystal photo. Good to see the season opened, although Southern Finland is being beaten by heavy rains.
ReplyDeleteThe air bubbles inside the crystals seem reasonably small compared to the total surface area of the basal face. So the light probably has enough room to make Wegener etc arcs. However, one would imagine that the air bubbles really get in the way and prohibit some light paths completely. But your photos show excellent halos... Hmmm, puzzling.
I too find the crystal photo of very good quality. Along with the bubbles near basal faces there seem to be cavities on some of the prism faces as well.
ReplyDeleteIn fact, I find it amazing that the halos needing good basal faces are this good! Apparently there was a big enough population with relatively little bubbles on the basal faces.
I do wonder about some of the structures on the prism faces. Some appear consistent enough to be interpreted as cavities but then there are some that seem a bit different in their nature (that one crystal in particular, near the center, towards top right corner). I wonder what they could be.
I know Marko has already spotted these too. Any new ideas?
Congratulations, Marko. Yes, the crystal photo is really good quality, I can see that the technique of photographing them has been improved. What have you done to the "system"?
ReplyDeleteWow Marko I can only dream of halos like it because our skies are cloudy and temps too warm.
ReplyDeleteI have to echo the same comments on the Hi-Def crystal photo I noticed there is a triangular column crystal near the top of the photo.
Most of the halo display crystal samples consist mainly of non-regular hexagons. Triangular or "triangularish" shape is common.
ReplyDeleteThat's why we see for example the sun pillar intensity treshold in these displays. Regular hexagons would not produce them.
I have to thank Jukka, Mikkilä and crystals for the good photo. Jukka and Mikkilä both contributed to my system (I pass on the boring details) and crystals were optimal because they were unusually large.