The great 24 February 2017 halo display in Pskov region of Russia

In the evening, I looked at meteoblue's meteogram (like I do everyday), and saw on it plenty of high-level clouds, but at the same time together with middle-level clouds. At 09-30 I woke up that to check whether middle clouds would not allow observing halos.

I came out and saw that the sky indeed was pretty dirty and contained not only cirrus but also low and middle clouds. But above the sun were the central part of UTA and diffuse pillar. I could leisurely to prepare my camera before halos became brighter.

After a few minutes, UTA became seen pretty well. Viewing the sky I was very surprised to detect the supralateral arc to the left of the sun. The arc was not bright but it was clearly visible. It was weird to see such good halos in such dense clouds. Clouds from different levels merged with each other. So at first, I did not understand that it was a big display that penetrated through the gaps of the lower clouds.

After 10-15 minutes came a big gap in those clouds and I saw the full Supralateral arc which was noticeably brighter than previously. I already was very glad because the arc in this form I saw only on my screen when I processed stacks. And at the moment I saw it in the sky with my own eyes. However, this was only a prelude of what was to come.

Wegener arc, subhelic arc, and blue spot on parhelic circle

Around 11-00 the sky started to clear and above the supralateral arc and a nice circumzenithal arc appeared. In that moment I noticed to the west a bright fragment of the parhelic circle which was low over trees. Cirrus arrived from this direction. While I changed the direction of my camera's field of view, I noticed also the anthelion. High clouds arrived quickly, and they were very uniform and smooth. The brightness of halos quick started to accrue. I ran in my home in order to show the current display to my father, and during this couple of minutes the brightness of halos increased even more. I ran back to my camera, and in this moment halos became extremely bright! The upper tangent arc was very perfect and sharp. The supralateral arc was brighter than a common primary rainbow! Probably it reached such extreme brightness not only because crystals were perfect, but also because the sun elevation was almost optimal. The parhelic circle was also incredible and looked like jets of light. Wegener arc was visually visible as well. Its oblique wide lines pointed out on far and weak anthelion. Around anthelion from time to time X-shaped arc was visible.

Near sun there are 9° halo together 9° column arcs

All sky view. Near anthelion there is Tricker arc

Anthelion and some of diffuse anthelic arcs

Upper tangent arc with diffuse upper 23° plate arc and sharp 24° column arcs. Thanks to M.Riikonen for the confirmation

Halos lasted in this bright form around 45 minutes. After the brightness of complex a few decreased, but all details continued were visually visible. I remember that I saw well crossing of Supra/Infra-lateral arcs on the parhelic circle. Also from time to time appeared 120° parhelia.

On the left there is 120° parhelion

At 13-10 was the end of this great display, only halos near the sun remained. Parhelia were most bright in this moment and seemed to me that near them were Lowitz arcs. But stacks showed that is not true.

Diamond dust season opened in Finland

On October 26 the pupils of the Särkijärvi school near the small northern Finland town of Muonio stopped suddenly their indoor activities and rushed out - somebody had noticed a halo wonder in the sky.

At the school were also excursionists from University of Lapland. Among them, Päivi Linnansaari happened to have a camera handy and took several photos of which a selection is presented here.

The display had all the basic flavourings of a great diamond dust display, including the helic arc, circular Lowitz arc and diffuse anthelic arc - the latter of which is seen faintly in the lower left image. But then there is also a new halo: the 46° contact arcs. Theoretically it has been known for quite a while, but no convincing photographs have come up untill now. The halo shows up in the upper right image as three arcs below the circumzenith arc. Probably a comparison with simulation is needed to get a proper grip of it.

The halo display made it also to local newspaper. Couple of kilometres from the location there is a ski center, so the halos may likely have originated from snow guns.

Subhorizon diffuse arcs with Liljequist subparhelia

Francesco De Comité took this great photo from an airplane between Brussels and Madrid in 7 August 2006 at 19h31. Unfortunately no more additional photos are available from this display.

There is really well developed diffuse anthelic arcs crossing subparhelic circle. Subanthelion point is illuminated by these arcs. In this case it is clear that there is no subanthelion, since bright spot on subanthelion point has clearly square shape caused by diffuse arcs. Column ice crystals have to have good orientation.

Other very rare halo shown in this photo is broader segments on parhelic circle on both sides on subanthelion point. Unfortunately these broader segments are not very clear and they are cutted by edges of the photo. These broader brightenings are so called Liljequist subparhelia caused by plate ice crystals. Liljequist subparhelia have been photographed earlier at least by Walter Tape (see Tape's book Atmospheric Halos in page 71). Tape's display is very similar than this Francesco's display.

Since Francesco's display has rare halo made by plate ice crystals, it would be a really good case to look for still undocumented 120° subparhelia. Hunt for 120° subparhelia is still going on...

Odd radius halos and diffuse arcs in Fairbanks

Alaskan town Fairbanks is renowned for it's odd radius halos during the winter. On 10. March 2006 there was odd radius halos but also diffuse anthelic arcs - a treat much less commonly seen in Fairbanks. According to Walt Tape the display lasted for several hours and was different in different parts of town. Outside the town no halos were visible, which indicates anthropogenic origin of the display.

In addition to diffuse arcs, another curiosity was also seen: odd radius column arcs. While they are regularly observed in high clouds, in diamond dust they have occurred only once before, at South Pole. The photo above, taken by Tape, shows poorly developed 9° odd radius column arcs as enhancements on the sides of the 9° halo.

Trickers and diffuse Anthelic Arcs in Germany

Alexander Wuensche from Görlitz (southeast Germany) observed and photographed these wonderful Anthelic arcs.

He writes: "In the morning of February 23, 2006, snow stars fell from the cloudless sky. The temperature was 2 deg below zero and there was a slight breeze from northeast. In the northern and northwestern direction the were remains of a Stratus and Stratocumulus cloud layer. In these clouds, the Anthelion with Trickers and diffuse Anthelic Arcs appeared.

The phenomenon was restricted to the direction opposite of the sun. In the direction of the sun I only spotted two small non-spectacular sun pillars."

By Claudia Hinz

 

Original post in Halo reports