Over the past years, the Fichtelberg – Keilberg/Klínovec twin peak region in the German / Czech ore mountains has proven to be an unexpectedly active place for diamond dust halos. As shown in a recent study by Claudia Hinz et al., this high halo activity may have already been present there for decades or even longer, resulting in local myths but sadly few scientific reports in the halo literature up to several years ago.
Another exceptional display was observed on the top of the Fichtelberg (1215 m) on December 18th, 2017, by Gerd Franze, the head of the local meteorological station. He took about 400 photographs from about 12.20 to 13.20 CET (at sun elevations from 16.0° to 14.3°). During the course of the display, the temperature increased from –3.6 °C to its peak value of –1.9 °C at 13:10, followed by a decline down to –5.0 °C over the subsequent hour. Wind was noticed only at very low speeds of about 2-4 m/s coming from between southern and southwestern directions. Fog from the bohemian basin was drifting over the mountain top the whole day. No snow guns were running, as there already was enough natural snow for skiing.
a) view towards the sun, b) view towards the anthelion, c) and d) corresponding simulations using the parameters below
Simulation parameters for HaloPoint 2.0
On March 26, 2017, I could observe this phenomenon for the second time. The first time I observed it in Munich about 20 years ago, when within a few minutes two boundles of “moving ripples” crossed a left-hand sundog. At that time I did not know what I was seeing. I learned it thereafter, also the name of the phenomenon, that it has been observed several times until then and that it may be related to acustic waves. Later, the video of the “extermination” of a sundog by a rocket launch became well known. But I did not see this phenomen again till March 26, 2017.
It is just a “must” for me to photograph with my pocket camera every halo I see mostly only to get the time mark of its beginning and/or end for the record. On that day I was several times on my balcony to check for halos. The sky had only contrail-cirrus (now officially termed Ci-homomutatus), but no halos. But once I discovered a faint sundog it may have been the only halo-active contrail-cirrus group of that day. I observed the sundog coming and going with the respective cirrus couds resp. the standing sundog against the moving clouds. The sundog was faint the whole time and all but remarcable. But then I surprisingly realized that there were some odd dark strokes crossing part of the sundog diagonally. Remembering the moving ripples, I immediately zoomed in. I could record this phenomenon in some pictures. It did last only about 30 seconds, but visually the dark stripes were much more evident than the photographs suggest.
The exceptionality of this observation was that the otherwise “moving” ripples were in fact “standing”: They moved with the cloud through the sundog. This can be seen very nicely on the photographs: the ripples seem to be a fixed structure of the cloud. But they were only visible in the area of the sundog. Outside this area the ripple pattern did not show up: the dark stripes were not there! Clearly recognizable is also the fact that each ripple began weak and increased its intensity towards a maximum in the centre of the ripple area, and to vanish at the other border of the ripple area.
Remarcable was also the fact that the ripples showed up only in a part of the cloud resp. the sundog area. For me it remains a mystery why (only) a small part of the cloud was “trapped” in these “acustic waves”…
Author: Christoph Gerber, Heidelberg (BW), Germany
Link to the topic: Collection of all known observations
6th January, 2017, I observed quite a clear reflection subsun in the southern Finland.
It was morning, local time around 11am. I looked outside and saw a nice sun pillar. And clouds, that were about to block the Sun. So I went to take photos of the pillar before it was too late.
I got the pictures and stayed for a while and saw the clouds running over the Sun. Surprisingly, the pillar didnt disappear. I waited for a little while longer but the halo was stubborn. Then I realized, the source was not the Sun, directly, but its reflection! The sea is a couple of miles away and wasnt yet frozen (map).
More pictures can be found here.
Author: Matti Helin, near Turku, Southwest Finland
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.
After having been hunting diamond dust halos since darkfall, at 1 am we withdrew along with disappearing crystals back to aparment to sleep. But this did not mean calling it quits. The forecast was for the conditions getting better, so every one hour each of us woke up in their turn to check the situation.
In three previous posts we have dealt with different stages of the 23 November display that had some interesting features, like an anomalous Hastings/Wegener arc and a possible 4th Tape arc. Here we show the rest of the material we got that night.
On 23 November 2015, we were watching diamond dust halos develop under overcast skies in Rovaniemi. As we stood on a rectangular field a couple of hundred meters across, we followed halos slowly gather momentum in the spotlight beam, reaching climax when clouds were cleared away for a short while – and revealing at the same time also a lunar display. Here is an excerpt from Marko’s observation log written the next day:
“The display just adds gear. We are looking at beautiful subanthelic stuff, subanthelic arc, diffuse arc… It becomes monstrous when the cloud almost disappears. That is when we get also a moon display with full parhelic circle. No one seems to be in a rush to photograph the moon display. The beam display is sheer grotesquerity. The laser scapel sharp, 100% pure glitter of the tangent arc and uppervex Parry.”
The image above shows what looks like a patch of Wegener or Hastings on top of the 22° halo. But instead of having the usual horizontal curvature, it is bending slightly downwards. Because of the view angle, though, the effect is not as evident as it could be. Anyway, if it were standard Hastings or Wegener, it would curve steeper up in the photo.
We have no idea how it formed, our attempts at simulating have come up empty-handed. The display was seen in Rovaniemi on 23 November, 2015, and the arc appeared at a stage when the display was still progressing to reach its peak.
Nine days later, in the beginning of December, we got another, better sighting, suggesting it is not exceedingly rare. In a similar manner, it did not occur when the display was at its best, but when the display was undergoing a momentary low. We will post about this later.
Jarmo Moilanen, Marko Mikkilä, Marko Riikonen
Crystal samples should be englightening, but all too often they just make you confused. The observation I made on 22 November 2015 in Rovaniemi is a case on point, although an observation recently published by Alexander Haußmann may now provide a solution.