Digging up old odd radius display for 28d spotting

Hello everyone,

after several talks with Alec, I decided to make some digging into my old odd radius halos displays to search for rare halos and find out some more 28d halo (and 13d halos too).

Here are some examples of what I found so far that might be interesting to submit here to your assessment. I hope you will find those cases interesting.

For some of them, I still have all the raw files of the sequence, for others, I kept few raw images, but for all of them (exposed here at least) I made various time-lapses to keep sequence in B-R rendering, colour rendering, stacked with 4 or 8 images each, like the one I presented earlier in this blog.

I will start with a sharp display of odd radius circular halos I got last year, in April, at the morning.
I'm not usually an early bird so I can miss some nice displays each year. For this one I got the chance to have the display still available to start a capture from my roof window. The center of my house is a stair tower which offer a nice blocking roof for the spot I am from. Therefore, with the shaprness of the display, the 9° ring was particularly well visible on B-R rendering before the sun comes out of the roof (because the diffusion of the light on the lens add noise up to the 9° ring area). There is a first image, B-R rendered from a sole raw image, to give a view of the sharpness of the event:

2022-04-20-SSE-[08h45à19h09]-bw-v4-crop-half-(1)
where we can see clearly 35°, 22°, 23°, 20° and 18° halos

Stacking with the above one as first image, with the 25 following images makes those odd radius halos more clear:

2022-04-20-SSE-[08h45à19h09]-bw-v4-crop-half-(1)-26s27-m
''-m'' stands for ''align manually'' in Registax 5, software I use to make my second processing of stacking if any.

Well, in the light of recent search for 28+° ring, this was one of my first tries even if I was expecting, like for the 13° halo, to find it when the rings are not sharp. But if you don't try, you won't find anything.
So there is a processing the the previous stack to enhance sharp halo first then eventually larger borders ones if any.

2022-04-20-SSE-[08h45à19h09]-bw-v4-crop-half-(1)-26s27-m-UsMl^n&m
''-UsM^n'' stands for Unsharp mask applied several times with various settings (m & n)
Do you see 28° ring ? Or could this be artefact due to unsharp masking ?

There is a folder on my drive, so you can take a look at the time-lapses of the day. As usual, better download it rather than viewing it as a Youtube video, to have a better video compression (as is the original one) Many years ago, I got a nice odd radius display at sunset, during a day of November 2014. The view is not ideal, as I placed my camera on the edge of a window, look south, with a wide angle rectangular lens, hence the distortion. (EoS 1200D + Sigma 8-16mm, set at 8mm). I was so amazed by the display I sent it to Nicolas Lefaudeux to have his expertise on the matter. And then he told me I caught the 28° halo, again (but I don't recall why this 'again') ;-) There is the display, B-R rendered, and unsharp masked.

1st of the odd radius sequence, after altostratus clouds went east, with unsharp mask done

And later in the sequence, after it vanished a first time, 28° ring was there again at the end, without unsharp mask applied [Stack]

Unfortunatly, I did not keep any raw file of this event.
There is a folder where are all the remainings.



And any old how, here are some I cannot say it is, but looks like there might be something there.... or not:

2015-03-07-[]-bw-[8-8]-UsM-[6-5]-UsM (16), Dole, Jura, France (and for the scary look of it!)

2017-03-11-[14h30à18h42]-bw-[8-8]-UsM-[8-4]-UsM (26)-7s7, Dole, Jura, France

2017-04-24-[13h57à20h36]-bw-[8-8]-UsM-[6-4]-UsM (18), Dole, Jura, France

2018-04-04-[18h39à19h19]-bw-[8-8]-UsM-14s14-USM, Pontarlier, Doubs, France

2018-04-09-[14h09à16h42]-bw-[8-8]-UsM-(21)_UsM-9s9-m, Jouhe, Jura, France

2019-05-23-[08h35à17h36]-bw-[8-8]-UsM-(20)_UsM-4s4, Jouhe, Jura, France

2020-04-17-[09h11à14h12]-bw-[8-4]-UsM-(153)-6s6-UsM, Jouhe, Jura, France

2021-02-16-[09h43à14h33]-bw-[8-4]-UsM-24fps(61)-6s6-UsM-histo-UsM, Jouhe, Jura, France

2022-04-11-[08h20à19h48]-bw-[4-2]-UsM-[2-2]-UsM(233)-9s9-UsM, Jouhe, Jura, France

2022-08-02-[09h32à18h09]-SSE-bw-[8-4]-UsM (305)-6s6-h9-h13-h18-h22-P23, Jouhe, Jura, France

2022-11-12-[14h09à16h09]-bw-[8-4]-UsM²-(40)-5s5-UsM-h35, Jouhe, Jura, France

And while browsing at all of those, I realized I got at least a dozen of 13° halos, with at least one with the Moon. Which could make a post after this one, for the record.

And a last one, not for the 28d spotting, but only because I like it a lot:

2021-05-23au24-[22h52à02h56]-bw-(152)-6s6-UsM-2s2-blr-UsM
Sharp odd radius halos with the Moon!, Jouhe, Jura, France

Now, a couple hours after starting this post, I think I may go get some rest ;-).

Greetings from France.
Nicolas R.

A clear 28° halo on snow surface

Sunshine has been a rare phenomenon in Finland this winter. On 16th January, the sky was finally clear and temperature had dropped to -25°C, so I headed to a nearby lakeshore to observe possible surface halos. There were indeed 22° and 46° halos visible on the snow, so I took a set of 335 photos by moving back and forth of a 50 m stretch of a road along the lake. The mirrored stack revealed that this was an odd radius display with 18°, 20°, 23° and 24° halos present. An interesting feature was that 22° and 23° halos were equally strong and well defined in the stack.

Two days later I got another chance to photograph surface halos in the same place. The temperature was -8°C. Only a modest 22° halo with some bright glints outside it were visible to naked eye, so I did not expect much from the stack. Nevertheless, I took 147 photos. This time the mirrored stack looked even better than two days ago: a strong 22° halo accompanied by several odd radius halos, including a clear 28° ring.

A comparison with the previous display (limited by blue frame in the photograph below) provided another surprise: the prominent ”22° halo” was in fact a 23° halo and 22° halo was missing. So this was an odd radius display with 18°, 20°, 23°, 24°, 28°, 35° and 46° halos. Although there are not many observations of 28° halo on surface yet, it seems probable that it is not as rare as has been thought. This gives some hope that a crystal sample can be obtained one day.

The strong 23° halo and the absence of 22° halo in this surface display is interesting. It means that the usual ”22° halo” on snow may in some rare instances be something else than it looks, but it is not easy to detect such cases from the abundance of common 22° halos. For example, the first observation of surface 28° halo on 7 April 2012 by Jari Luomanen and Marko Riikonen looks rather similar as the current one, and it may perhaps contain 23° halo instead of 22° halo (yellow frame below, photo Jari Luomanen). Although all photos in this collage were taken with Samyang 8 mm fisheye lens, the result should be viewed with caution due to the robust alignment.

Odd radius display at low sun in Berkshire, UK

11-frame stack at sun elevation 2°: unsharp mask and colour enhancement (top), and background subtraction + blue-minus-red colour subtraction (bottom; the latter by Nicolas Lefaudeux).

In the evening of 24th May 2020, a notable display of odd-radius halos and their associated plate arcs occurred in Berkshire, UK. I first noticed faint traces of circular halos - 20° and 23° as I could later confirm from photos - at around 19:20 BST, when the sun was at 13° elevation. Less than 30 minutes later the sun had come down to 9° and first signs of the upper 20° plate arc appeared, making obvious the need to find a view down to the horizon. The display got weaker after some time but regained some intensity less than 30 minutes before the sunset. Unfortunately there were some lower-level cloud interfering with my view for most of the observing time.

Stacked and further processed images from the first stages of the display (below) reveal 18°, 20°, 23°, and 35° circular halos in addition to the aforementioned 20° plate arc. At the end of the display (above), the circular halos are less clear, but plate arcs at 20° and 35° show up better. Most interestingly, perhaps, there are suggestions of 28° circular halo and the associated plate arc at the upper left-hand side at solar elevations 7° and 2°. Previously 28° arcs have been reported in the Lascar display of 1997 and in a few more recent occasions in China, but possibly never before in Europe.

50-frame stacks at sun elevation 9° (top) and 7° (bottom): Background subtraction (left) and background subtraction + blue-minus-red colour subtraction (right).

Odd Radius Display, Bolton, United Kingdom

On the 5th April 2018, there was a short lived but rather nice odd radius display in Bolton, a town situated in the north west of the United Kingdom. As I was preparing to go to work, I noticed the top of what I initially took to be a 22d halo. However, it rapidly developed and became more complex and very soon an 18d became easily visible to the eye. The display lasted about thirty minutes in total and I was only able to take a few single shots and a couple of stacks before it began to fade and I had to leave. Upon processing the images, 9, 18, 23, 24 and 35d halos with attendant plate arcs were identified as being present.

Processing courtesy Nicolas Lefaudeux.

Reign of the Pyramids

Well seems like most of the rare halos I have been getting are pyramidal this year and I like pyramidal stuff. This morning I got up and later on 18 and 23d halos formed along with a nice upper 23d plate arc and 18d plate arcs. Later on faint 9d halo and when looking at the convex mirror faint 35d halo and it shows up in Photoshop.

Recent displays from Northwestern Russia

In this post I want to share some of my observations from last month, which I made in St Petersburg (from 15th April to 5th May) and in Pskov Oblast (from 7th May to present time). In total there were eleven displays, six of them comprising pyramidal halo forms. Many of these pyramidal displays were minor, so I will not present them.

20th April

The photo on left shows a purely odd-radius plate complex. There are only the upper 23 plate arc with its 23 halo and a couple of 18 plate arcs. On the photo on right you can see fragments of weak odd radius circular halos. Together with the broad 22 halo at the 02-00 position there is the 20 halo and also the diffuse 35 halo.

28th April

Together with classic halo forms in stacks pyramidal halos appeared with odd-radius plate arcs. On photos above you can see lower 24 plate arcs with the 24 halo and the 9 halo (with possible the lower 9 plate arc). The weak and diffuse upper 23 plate arc is also available.

30th April


In the morning there was a short display which lasted less than one hour. The display was not predicted by the meteogram, so maybe I missed most of the display, which was earlier that morning. In any case I saw bright parhelia with the colourful circumzenithal arc, and got in the stack the strong parhelic circle and the upper suncave Parry arc together with the nice upper tangent arc. I think it is the Parry arc, and not an upper 23 plate arc, because the display does not contain no other pyramidal halo forms, and the arc looks pretty sharp.

1st May

In the morning I observed the large and bright upper tangent arc for around one hour. Infralateral arcs were easily seen with naked eye. Together with bright parhelia I saw fragments of a parhelic circle. In stacks the rare Wegener arc was found.

5th May

On that day there was a protracted display, that lasted between six and sixteen hours. But my camera had recorded interesting halos only at the start, on the sunrise. It was an odd-radius circular complex which contained pyramid halos with radii 9, 18, 24 and 35 degrees. It seems the 24 halo included rudimentary upper and lower 24 plate arcs.

10th May

No rare halos on that morning but I saw the supralateral arc visually very well, that happens not often. A curious circumzenithal arc appeared a little later. The CZA was diffuse, that is not typical for this halo. 

Halos from oriented pyramids in the spotlight beam

On the night of 20/21 January we photographed oriented pyramid crystal halos in the spotlight beam on two occasions. The first occasion, shown above, got us completely unawares and the odd radii stuff was all gone in the next shot which would have had the exposure right. Colored and solid upper and lower 9° plate arcs were seen, but if they were still present when the camera was placed in the beam, they are nevertheless washed out by the overexposure. In the photo one still sees the 35° halo and lower 20° plate arc. The lower 9° plate arc was of the 23-6 type as the lamp was about 5 degrees below below horizon.

We drove around and switched on the lamp here and there, stubbornly trying to get a rerun, but to no avail. Diamond dust was already on the retreat, the air was drying up even though it was around -33° C. Yet we managed to get something just before it all evaporated, as shown by the image here:

A little simulation study as was necessary to see whether it was column (left) or plate (middle and right) pyramid stuff, but that did not give definitive answer. The plate scenario simulations are identical except that in one is 22° halo and in the other 23°. The 35° and 18/20° stuff above the lamp were initially noticed visually which prompted us take the photo series for this stack.

These last photos were taken at 3:30 am. The two photos below are the first photos of the night at 6 pm. We photographed these lunar and beam displays simultaneously. No odd radii yet at this early hour.

Marko Riikonen / Jarmo Moilanen

originally published in Halo Phenomena

Pyramidal crystal halos

A funny coincidence that a halo-observer may want to experience is travelling to Egypt and seeing some pyramidal crystal halos.

This odd-radius display was photographed by Márk Laczkó of Budapest, Hungary somewhere over the southern borders of Romania. He was sitting on an airplane heading towards Egypt on 27th October. When he realised they were flying in cirrus clouds, he deliberately started looking for some halo phenomena. The surprisingly well distinguishable 18°, 20°, 23° and 24° halos were visible for about a minute at 06:21 UTC. Unfortunately, there is no documentation or report of a possible 35° halo. The original photo and two other pictures are also available (#1 and #2).

 

by Ágnes Kiricsi

 

Original post in Halo reports

Pyramidal halos 8-14-07

After weeks of seeing no nice halo displays I was at work today on breaktime and I saw 22 halo and upper 22 deg tangent arc. I put my sunglasses on and I soon realized I had an odd radius display at hand. In all there was 9 deg. halo 18 deg halo and the outer halo who knows it could be 22 or 23 or a combo of both. The upper arc is convincing it looks sharp and I think it might be 22deg upper column arc but not sure. One photo is an original and the other has USM applied to make the halos stand out better. This is a good odd radius display for me but I know there is a lot better.

Odd radius halo 6-19-07

While at work on break time I noticed there were cirrus clouds in the sky and I decided to check for halos and I got three odd radius halos which were 9, 18 and 22 or 23? degree rings. I took a few photos. I unsharp masked one of them the show the halos more clearly. This was probably the only halo highlight of June but nothing super special but it beats nothing.

Moon pyramidal halo complex in Czech Republic

In June when conditions for observing halos aren’t fine because of low full moon elevation, I have had my best observation ever. On cirrostratus veil divided from cumulonimbus cloud firstly appeared 9° halo and later thick halo at 22-24 area. After stacking 20 pictures, it turned out to be 23° and 24° halo. Fragments of 20° halo were not recognizable until stacking photos. Halos were seen at the highest intensity for about half an hour.

Martin Popek

Odd radius halos at Crete

These odd radii were a little bit surprising, I didn’t expect something like this at Asimenia beach in Kavroz. I had been waiting for any halos for five days and the first display was directly pyramidal 18°, 20° and 23° halos. Fortunately I had a piece of welding glass because photos I took without this protective glass was totally unusable because of reflections. The display originated at very thin cirrus clouds.

Martin Popek

Odd radius halos in Czech Republic

On April 5th 2007 there was typical nice, but, dry“ cirrostratus in the sky without presence of halos. I was continuously checking the sky and after 10:00 I noticed very faint halo that had unusually wide upper part. That was very suspicious to me so I started to take photos which were after processed by Registax. You can see the result in the output picture. There are two separated halos which I later identified through the comparison with night sky, as 20° and 23° halos. Maybe there is also 35° halo, but it cant be certainly identified from the picture. The phenomenon could originate at 0,3-0,0-0,0 or 1,0-0,0-0,0 crystals.

I saw very similar displays with nice, "dry" cirrostratus and then with faint odd radius halos on June 22nd 2006 and August 26th 2006 so that is quite interesting.

Martin Popek

First odd radius halos observed 31st January 2007

While at work on break I saw some cirrus clouds gather in the sky and I later saw a halo appear so I got my camera out of the car and my sunglasses. As the minutes passed I notice that there were three halos: 9 degree halo 18 degree halo and possible 23 degree halo. The left side of the 9 degree halo looks strange because it is brighter on one side and has a somewhat vertical look to it.

When I later downloaded the pictures I went through them with adobe photoshop and I applied the USM and I noticed possible 20 degree halo and even a 35 degree halo! You can see at least 4 halos in the enhanced photo. The possible 9 degree column arc and 35 degree halo have been pointed out with black arrows.

Odd radii in Czech Republic

During the Czech halo observers meeting in Kuncice, high clouds created some good displays. This odd radius halo complex was seen on 14. August. It shows 9,° 18°, 20°, 22-24° and 35° halos. Judging from the non-uniform intensity distribution of some of the halos (9° and 20° halos being brightest on the sides), this display was caused by poorly oriented columnar pyramid crystals. It's also interesting that 20° halo is brighter than 18° halo. This type of occurrence is uncommon.

This is stacked image processed by Roman Manak and Patrik Trncak. Original photos were taken by Martin Popek.

By Marko Riikonen