On January 22nd 2017 I had the opportunity to witness a halo phenomenon in my home town for the first time.
The observation took place in Jena-Maua Germany (50°51’59.4″N 11°36’02.0″E) from 8:45-10:45 CET within about one kilometer. The maximum activity was observed between 10:15 and 10:45 CET.
We had a high-pressure weather situation with more and more lifting and dispelling fog (starting with 50m AGL) in the ‘Saale’-valley. Measured temperatures were about -10 to -6 degrees.
After recognizing the lower sun pillar besides the left Subparhelia in front of the fog boundary (seen from 300m height) I drove closer to the fog and found myself standing inside diamond dust (height 150m).
Between 9:45 and 10:45 the following types of halos have been witnessed: 22° halo, left and right parhelia, upper and lower tangent arcs, upper and lower sun pillar, Circumzenithal Arc, parhelic circle, Anthelion, left and right 120° parhelia, Supralateral arc, Parry arc, Subsun, left and right subparhelia, Tricker’s anthelic arc, Tapes arcs, Heliac arc and subhelic arc.
Uncertainties exist concerning the following observations: Lowitz arcs and Moilanen arc.
To sum up the best possibility of seeing this phenomenon was inside or near Jena-Maua – a small district of the city Jena which has some industry chimneys (compare the last photographs with the smoke trail). It seems legit to suppose that industrial fine particules conduced sublimation/condensation nucleus for the diamond dust development.
Author: Marco Rank, Jena, Thuringia, Germany
In an earlier post I told simulation attempts were not succesful for this display. Well, I really did not put that much effort into it. Now I have given it a fresh look and managed to get some succees.
The problem was the subhelic arc and anthelic arcs that could not be get rid of. In new simulations made with HaloPoint the subhelic arc issue is pretty much resolved and the anthelic arcs also play it low key.
This was a good no-hassle night of diamond dust hunt. The swarm was stationary and I didn’t have to pack up every 20 minutes to follow its whims. During the 6 hours of observing it was necessary to move only once. Also, both two locations were quite good concerning the light pollution. Especially the second place, where I wrapped it up in the morning ours, had a really dark segment which I used to light up the anthelic region.
As for the halos, the start of the night at around midnight was not so inspiring. As I arrived to the snow deposit area near the river, a sneak peek in beam revealed a run-of-the-mill plate display and I though it will just get worse because the temperatures were in the bad range, around -15 C. So I decided I might as well give some minutes for the half-moon display that had a smudge of Moilanen arc. In photographs it was transformed into a nice V-shape.
In snow gun diamond dust displays Parry orientation is often strongly emphasized in relation to column orientation. There may be no signs of column orientation at all, except for perhaps a slight tanget arc brightening on top of 22° halo.
Spotlight displays are great in that almost every time you photograph them, you realize you understand halos less and less. This time the puzzle is: Why Wegener in the image above is so strong in comparison to other reflection halos? No subhelic arc is visible and neither there seems to be diffuse arc – I think the spikes at the subanthelic point are lamp artefacts. Of course I can’t not say that for sure, but around the subanthelic point even weak stuff shows up easily to the eye, so had there been diffuse arcs, I should have noticed it. If we accept this, then, in addition to the Wegener, the only suggestion of column reflection halos is what looks like a short patch of Tricker arc cutting across the sub-Kern arc (see the simulation below for comparison).
A simple diamond dust display that I photographed on the 6th of this month in Rovaniemi, shows above the Moilanen arc another, weaker V-shape. As I uploaded the photo on Taivaanvahti, I was not conscious of the effect, it caught the sharp eye of Panu Lahtinen and Reima Eresmaa who commented on it. Then some photo processing made it stand out more clearly. The version above was worked by Nicolas Lefaudeux. It is a stack of 13 images taken during 125 seconds.
Showcasing the last winter’s spotlight displays is still under way, but fresh produce is already coming in. Here is the new crop that I harvested on the evening of 5th November in Rovaniemi. In the image above the lamp is around -6 degrees below the horizon and both parhelic and subparhelic circle are visible. Slight intensity enhancements in them on the side of the sky opposite to the lamp are suggestive of Liljequist parhelia. Included are also Sub-Kern and sub-120° parhelion. I did not spot sub-Kern this time, but the latter was quite discernible when running alongside the beam. As usual, it was a pale pillar of light in which no individual crystals were detectable – very different from the intense subparhelic circle patch towards the subanthelic point, which is always made of pure glitter.
On the fifth of November the diamond dust season opened in earnest, when Esa Palmi photographed a major display at the Kittilä airport. While the sun side is always the attention gatherer, the main attraction of the display is really on the opposite part of the sky, where a strong subanthelic arc dominates the scene.
Here are shown the rest of the photos from the night that yielded the second capture of the anomalous Wegener/Hastings. From the golf course parking lot, where we took those photos, we walked into the golf course, and were able to place the lamp even lower down.
On the left anomalous Wegstings, on the right normal
In an earlier post we showed a photo of a weird downward curving patch of Wegener/Hastings. Here is another case that occurred 9 days later on December 2, 2015. This time we also got a nice comparison to normal “Wegstings” by superposing photos taken from the same camera position.