Weak odd radius display on 09 March 2017

Yesterday in St Petersburg was an odd radius display with a predominance of plate forms.

The morning was cloudy. Around 11-30 sky started to clear. After half an hour the whole sky was covered high clouds. But I did not see any halos. It seemed it was usual bad clouds, which not produce halos. Nevertheless, in some moments I saw very weak and wide 22° halo with something resembles upper 23° plate arc. Also was an episode when I saw compact CZA, which apeared without parhelia. My suspicions have only become stronger, about that I faced with subvisual odd radius display.

It was brilliantly confirmed when I returned to home and processed stacks. I was able to identify such pyramidal forms as upper 9° plate arc (possible), upper 23° plate arc, lower 24° plate arc. Also were captured 9, 18, 20, 22, 24, 35 (very diffuse, link) and 46 halos. Odd radius halos lasted 50 minutes, until 13-30. Then until the end of display (until 15-30) were captured only weak common halos, such as upper tangent arc, parhelia and 22° halo.

It was fourth display since 15 February, which includes pyramidal halos.

Snow gun generated column display

On the night of 15th November 2016 (the night of the "supermoon") I was out of the city photographing the full Moon. The humidity was extremely high, which was evident by a huge aureola that was surrouding the Moon.

I was keeping an eye on webcams located at nearby ski centres, because the temperature was dropping below zero and snow coverage was scarce, therefore I was hoping for some snow gun action.

Few centres were operating the snow guns, but no diamond dust formation could be seen, so after a while I decided to return back to the city, but still keep an eye in case the conditions change. According to my previous post, Bílá ski centre is supposed to be the holy grail of diamond dust halos around here. But that is not true, there is another ski centre which generates diamond dust very frequently. I stayed up the whole night because I knew something would happen, and I was right, the ski centre I was talking about started generating halos, so I packed up my things and went again.

It is slightly further away than Bílá, so the trip took a while, but it was totally worth it:

This display, to my astonishment, was generated by a single snow gun (in the picture above it is located just behind the trees). No low hanging stratus, just high humidity and one snow gun. And it wasn't even on my previously planned location, it was actually a few kilometers ahead of it.

There are some indications of Parry oriented crystals, uppercave Parry is present and lowercave maybe too. indicated by a brightening on the circumscribed halo. Lowervex Parry was not seen. Wegener was maybe there, but the display itself was changing quite rapidly and I don't think my photos captured it.

Eventually I have decided to finish driving to my location. No halos there, and as I was returning, only faint and diffuse 22° halo was the only one left in the sky.

The crystal swarm was fairly thick, which can be seen in the main photo - the infralateral arcs were hanging in front of the forest. An amazing sight.

Fun addition: I had actually forgotten my gear at the location, and only realized it at home, so I had to return. It was still there!

Halos and fogbow in the same mix

To photograph a fogbow simultaneously with halos one's best bet may be the foggy autumn mornings with high clouds in the sky. (I leave the possibility of an exhalation fogbow unmentioned).

That should be easy enough. However, connoisseurs might demand the criteria to be that both phenomena must appear in the same cloud. That's making the task a good deal harder. Below freezing temps fogs sometimes have a meager few crystals thrown in the mix and there may be a pillar visible together with fogbow, but anything resembling a proper display is highly uncommon in my experience.

Actually I have never seen one - not until the night of 12/13 December 2016. On that night I was photographing halos at Jokkavaara gravel pits east of Rovaniemi at around -27°C. After the display took a worse turn I went for a little ride to see how things looked a kilometer or so in the city direction. It was the same crap and I returned to the gravel pits.

What a surprise it was to see the place now enshrouded in thick fog. Having just reconnoitered the surroundings I believed diamond dust was right behind the corner, and with the wind being towards the gravel pits, I wondered if the fog might soon start freezing.

True enough, crystals started glittering among the matte fog droplets and it didn't take long to have passable parhelia in the spotlight beam together with fogbow. The more halos intensified the fainter the fogbow became as diamond dust ate away on the water droplets.

It would certainly have been a splendid display if the process had gone all the way. Water cloud born displays tend to be violent. But the fog got an upper hand and situation was reversed to where it started from: only fogbow in the beam and no crystals, no halos. 

So this was a uniform mix of fog droplets and ice crystals. More common are situations where wafts of pure diamond dust and pure fog are alternating in the slight breeze. If you are taking, say, 30 second exposures, an illusion of fogbow being visible at the same time with halos can be created in the image when they in reality occurred at separate times.

Now what if only a display from photons of sun would satisfy the connoisseur? That's really amping up the challenge. There do exist some reports of simultaneous halos and fogbows from polar explorers more than century back, at least from Henryk Arctowki. The only photographs may be those by Ed Stockard in the Greenland Summit Station. But it is not certain if in this case the stuff occurred as one mix or the crystals and fog droplets were as separate layers.

Map in the sky

January 12th 2016 Mia Heikkilä noticed some peculiar light formations high in the night sky of Eura, Finland. She took some photos of the phenomenon. Camera revealed that formations consisted of spots and lines. She posted the pictures in Taivaanvahti where the phenomenon was recognized as an array of light pillars from street lights mirroring a network of streets. There have been some previous cases where streets and even their side streets have been recognizable from high floating pillars, but this is incomparable what comes to complexity of the "map".

In the second picture, there is a comparison between the "celestial" and "terrestrial" map (latter being mirrored for easier comparison). One can conclude, that zenith is in the uppermost part of the picture. There the pillars are seen directly from below, making them appear as dots. Away from zenith region, pillars are seen ever longer, as viewing angle increases. Also, one can notice, that parts of the farther streets "circling" the observing place are represented by pillars side by side forming a dotted line, whereas streets that are "radiating" from viewing location are represented by overlapping pillars fused together to a continuous line.

Another conclusion from the geometry of the pillars is that the light source isn't streetlights directly, but their light circles on the ground. It's quite amazing, that a divergent reflection from divergent light source can still produce pillars high in the sky.

But how high were the pillars? Several persons did independently calculations to find that out. Conveniently, there is a star field photo integrated in the picture for getting angular references. Measures of "terrestrial" counterparts of halo formations could be taken from topographical map. Results didn't deviate much from each other, averaging in 2,1 kilometers for crystal layer height. One calculation was also made to find out the thickness of the crystal layer and it resulted about 200 meters. Atmospheric sounding data later that night from Jokioinen (about 80 km from Eura) showed a sharp inversion layer just over 2 km. That's well in line with calculations.

One of the most common halo forms but how the display is presented - far from common!

Odd radius halos with Wegener and subhelic arcs in the UK

A short-lived display of relatively high quality occurred in Berkshire, UK, in the morning of 4th March, 2017. A routine check at 9:35 local time suggested the presence of faint 18° and 23° parhelia, in addition to the usual 22° stuff, so I collected my camera, tripod and blocker and set up the system in a nearby park area. After just 25 minutes the display was all over, but there had been enough time to capture three 30-frame series for stacking.

In addition to the 18° and 23° parhelia, both visible to the eye during the display, the processed stacks suggest parts of 20° and 35° (and possibly 24°) circular halos. Unfortunately, the region of 9° halo is over-exposed in my photos. However, as far as my visually-based observations are to be trusted, there simply were no halos 9° from the Sun.


Given that we are dealing with a cirrus display here, I find the presence of both supralateral and infralateral arcs indicative of fairly ideal column crystals. This is confirmed by the side-view stack, as faint Wegener and subhelic arcs can be identified. The latter crosses the parhelic circle near the tall tree at the bottom. Just slightly further away from the Sun, there is a 120° parhelion too.

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.

Psychedelic colors in diamond dust

Occasionally diamond dust glints in pink and and cyan colors. Walt Tape, who saw the effect once in Fairbanks, called it as the psychedelic colors. Here are a couple of photos of one psychedelic case this winter. The image above is a maximum stack of 19 frames with 2.5 and 1 second exposures. Below is a single frame with 2.5 second exposure. And below that a maximum stack of 9 frames with 6 s exposures. Colors have been observed so far only in spotlight displays. How they come about, I don't know. A crystal sample could give some answers.