[Halo] 2023-10-10 Pyramidale inkl. 23°-parryförmigen Bogen

[Marcel Becker]

Hallo zusammen,

nachdem zuletzt seit dem 7.10. (obere Lichtsäule) keine Halos mehr hier in Kirchhain auftraten, so zeigte sich heute wieder etwas. Allerdings war das wieder so gut wie gar nicht visuell erkennbar, sodass ich abermals Bilderstacks mit USM und/oder RB-Methode einstelle.
Gegen 13:30 Uhr bei einem Sonnenstand von 32° konnte ich fotografisch was nachweisen (Stack aus 35 Bildern mit RB und USM):

Sichtbar: 22°-Ring als Fragmente, beiden Nebensonne und ein Hauch von 9°-Ring.
Die Nebensonnen verschwanden dann innerhalb der nächsten halben Stunde und auch der 22er war kaum noch nachweisbar. Interessanterweise zeigte sich dann oben ein parryförmiger Bogen:

Auch in der USM-Variante ist dieser weißliche Bogen sichtbar (unten rechts an der Sonne ist zu dem ein Kranz):

Ich würde auf den 23°-parryförmigen Bogen tippen, denn Säulenkristalle waren offensichtlich nicht vorhanden (kein OBB oder ähnliches, dafür aber wohl der 9°-Ring). Dieser Verdacht wurde später erhärtet als dann der 9°-Ring und Teile des 18°-Ringes sichtbar wurden (Sonnenstand etwa 30°):

Auch in der USM-Variante gut erkennbar:

Interessant finde ich, dass der 18°-Ring nur links und rechts von der Sonne zusehen ist und sonst wohl gar nicht. Ob da aber die 18°-Lateralbögen im Spiel sind, möchte ich erst einmal nicht festlegen, wobei es diese nicht ausschließt, zumal diese wie der 23°-parryförmige Bogen an pyramidalen Eiskristallen mit vertikal ausgerichteter Hauptachse entstehen

[Carl Herzog]

So langsam könnte bei uns mal was anderes kommen, als nur Pyramidale

Die 18°-Lateralbögen waren ein Zeit lang auch nachweisbar. Insofern ist es wahrscheinlich, dass es oben der 23°-parryförmiger Bogen ist. Ob mit oder ohne Parry ist wie immer die Frage. Ob man das anhand nicht-vorhandener Halos ausschließen kann?

Pyramidale und Horizontalkreis:

Nachweis der 18°-Lateralbögen:

Nachweis 46°-Ring, Berührungsbogen, Zirkumzenitalbogen:

Im letzten Bild ist so etwas wie der von Nicolas angesprochene 13°(12°)-Ring zu erahnen. Ist freilich ein sehr stark mit USM beabeitetes Bild, um den 46°-Ring klar darzustellen.

Viele Grüße, Carl

[Marcel Becker]

Hallo Carl,

interessant, dass die 18°-Lateralbögen wohl tatsächlich vorhanden waren. Zumindest sieht es bei mir besonders rechts am 18°-Ring verdächtig danach aus. Gut, dass es bei dir eindeutiger ist.
Zum Parrybogen: kann der auch ohne Berührungsbögen/umschriebenen Halo auftreten? Zumindest hatte ich vorher noch nie einen Parry ohne OBB/umschriebenen Halo gesehen. Beide entstehen ja an Säulenkristallen, wo die Hauptachse horizontal ausgerichtet ist (beim Parry sind ja noch die Prismenflächen parallel zum Horizont ausgerichtet).

[Nicolas Rossetto]

Hello there, we had similar halos that day too in France, eastern part, with a nice 23° sundog like yours.

N.R.

[Carl Herzog]

@Marcel: Das ist ein sehr guter Hinweis! Der obere Berührungsbogen war bei vielen der anderen Pyramidalhalos auch nicht dabei. Dort hat es sich dann wahrscheinlich immer um den 23°-parryförmigen Bogen gehandelt. Ich sehe ich muss noch ein paar Beiträge vom September korrigeren Und ich muss die Eiskristallvarianten mit in meine Statistik aufnehmen.

@Nicolas: Do you mean the 23° upper plate arc on top of the 22°-ring? It looks just fantastic. Also, I noticed in my third image that there is a slightly brightened band between 9° and 18° that could be a hint of the 12°/13° ring. What do you think?

[Nicolas Rossetto]

Indeed, on your last image (and a very slight hint on the second too), you clearly have the so called 13° halo (even if the angle is not quite 13° indeed, and the the red part of the ring, so the grey part in B-R rendering has at least 1° between it's inner and it's outer borders, if i may say).

And yes, what I call the 23° sundog is the "23°-parryförmigen Bogen". When I first read about this arc back in the 2010's, I found the name 23° sundog, even if it was not on the same height as the sun and I now call it that way (and tag it "P23" in my pictures). On the shown image, the blue part of it was clear and thick so the B-R rendering show a nice white form which make him really different from the upper Parry.

And I think Marcel would not be far from getting one too maybe if he could stack more images from the raws files if he have some.

By the way, do you have any information already there somewhere in the forum about the set up you are using (camera, lens, glass dome, powering, ...) ?

[Carl Herzog]

@Marcel:
Wie Nicolas vorschlägt, könntest Du Deine Bilder mit einem etwas größeren Stack verbessern. Wobei es dabei mehr bringt die Zeitspanne zu vergrößern, anstatt das Aufnahmeintervall zu verkürzen, da die Wolken dann beim Stacken besser gemittelt werden und entsprechend nach B-R besser anuliert werden. So bekommst Du denke ich auch die Beugungsartefakte der Sonnenlichtreflektion an den Objektivlinsen in den Griff. Unabhängig davon kann man die Erkennung in den Bildern erhöhen, indem man nicht cropt bzw. einen stärkeren Weitwinkel einsetzt. Denn je kleiner das Abbildungsmaßstab des Halos in den dargestellten Bildern, desto besser erkennt unser Auge das Halo.

@Nicolas:
Regarding the 23° upper plate arc, when googling I cannot find any use of the word sundog for it (where did you find it?), and because of it's dimness I would not have thought of a sundog. Here in the AKM the short EE69 is used (https://www.meteoros.de/themen/halos/haloarten/ee69), although probably 23arc would be the name I would use if there was no numbering yet, even if the arc is often not at 23°... In this regard it is actually similar to the sundog, only in vertical direction.

I have an automated allsky-camera on the roof of my house, but its images are mainly for monitoring purposes, only used in emergency cases when I missed a halo, as the dome has some reflections (an example is here: download/file.php?id=31353&mode=view). The allsky camera is an uncooled color astro camera with an MFT-sized sensor, with a Laowa 4mm F2.8 circular fisheye lens attached, and protected by a simple polycarbonate dome (the one from the Starlight Xpress Oculus) and a custom made housing. Cabling goes through the roof into the house to an Intel NUC that records the images. Now, most of the images I post here in the forum are shot with a Nikon Z6II and a full frame circular fisheye lens (without any dome), but that is something I have to manually setup when weather allows.

[Nicolas Rossetto]

In this regard it is actually similar to the sundog, only in vertical direction.

Indeed, here was the source of "my" "23° sundog", that was in fact 23° (upper) parhelion, with the fact also that sundogs and parhelion are the same to me. (So the "P23" mentioned earlier, P is for Parhelion). And you are right, the "23°" is not accurate as it varies with the sun elevation but the minimum angle of deviation with sun position is 23° when the sun is about 47° high.

www.atoptics.co.uk/ which is now at old.atoptics.co.uk/ has been my major source of knowledge about atmospheric optics at the beginning of my interest in such matter, along with Hans Häckel books, 15-20 years ago and I kept more or less accurate names for some phenomenon since that time ("fog bridge" instead of "fog bow", etc).

that is something I have to manually setup when weather allows.

I know what you mean, I do this for almost 15 years now, and I wish I could set up a full automated camera for that purpose, but I don't have any suited spot for it at home. Thank you for the set up details anyway. Indeed the reflections "kill" the images sometimes, especially when you are looking for a particular form of halo.

[Carl Herzog]

Hi Nicolas,

15 years is a lot of time I started in 2021, but only this year things got more systematical, when I moved my allsky camera from the balcony to the roof. Since then I have recorded by far more halos than before. The housing for the allsky camera is very light and stable, so that it can be mounted on a pipe (it could even have been a long pipe going from the balcony to the roof). I am currently looking for a multicoated glass dome to minimize reflections. The portable option with the Nikon camera works well too, but that's because I have access to the roof, and because I use a tracker, so that the camera can run for 10 hours or so without intervention (with a small powerbank connected to the camera).

I am currently creating a german-englisch translation list for all halo types, starting with the german names used here at the AKM and the english ones used by Jarmo Moilanen and Maria Gritsevich in their "inventory of atmospheric halos" from 2022. Things are more complicated than anticipated. In english there are different names for the same halo, probably for historical reasons, but also there seem to be no standardized naming. For P23 I found (among others) "23° pyramidal upper parhelion", which seems strange, as pharelion means "beside the sun" in ancient greek (according to wikipedia). On the other side, the AKM naming is also not trouble free. For example with the Lowitz arcs things get very confusing. And the Moilanen/Gritsevich list does not manage to use unique clear names for all the halos, and has plenty of rare halos for which I cannot find a german name. Probably having unique international IDs for the halos would be the solution, to be able to find things when googling.

While creating the halo translation list, I did simulations with HaloSim for each single crystal type and orientation combination. I found it very difficult to simulate P23. The other "odd" angle arcs are perfectly simulated, but P23 is incredibly week, never matching the pyramidal displays I recorded so far. Only adding parry oriented crystals get's me nearer to the displays I recorded, which would mean that in all my images it's not P23 alone, but a lot of parry arc too overlapping P23.

Btw, I also prefer the old atoptics site to the new one. Not sure how the new one was created - if a human being added text or AI was used, but some things in the new wording look strange and repetitive to me.

Regards, Carl

[Nicolas Rossetto]

Hello Carl,

well, this is really a big amount of work you are doing there for the translation list for all the halos, and I understand better why you were surprised by the "23° sundogs" name. Indeed, para means beside, and it is more commonly on the right or on the left but there are all the other direction for beside (so maybe more like "around, without circling" is I may say , as I am not a linguist).
I tried in the past to find a french translation for all these names but I were quickly stopped by the fact that first, those atmospheric effects are quite not known in France (besides the rainbow), even by all the meteorologists and optic-specialists I talked to, and second, because the french community of halo watchers is quite reduced (If we are 5-6 in the country to regularly track and picture them, and expose some of those pictures on the web, it is the maximum)

For HaloSim, I used to make P23 nice with this set-up:
Shape: Pyr_30_30_30_27.98 or the other one (Pyr_20_30_90...)
Orientation: Plate (with less than 1 deg of dispersion)
Ray Filter activated with 2 faces traversed (no internal): #1 as entrance and #20,21,22,23,24,25 as exit.
Still works well when I simulate it.

For your all-sky camera set-up, it reminds me of the one Nicolas Lefaudeux got when he was living in Paris (we even were neighbour at this time). Here is the blog he made at the time (if you do not already know it). I hope you will be able to get rid of the essential of the reflection with your new dome.

For AtOptics from Les Cowley, indeed the new form is strange, as it emerged in september this year, couple years after Les stopped refreshing the original website. Hence it is hard to navigate for this or that information. Hopefully the old one is still there, when you manage to find it.

Salutations atmosphériques.
Nicolas

[Elmar Schmidt]

Well Nicolas,

I might jot down here, that it is not the number, but quality of contributions that counts, especially when I think of your namesake N. Lefaudeux's work. I also might give links to two of your countrymen's nice websites, which I occasionally look up:

http://vjac.free.fr/skyshows/
http://www.pixheaven.net

Of course, we Germans are known to be addicted to form and join clubs for just any pastime, as shown by the AKM, even if that it is not always free of problems

As Carl already has pointed out somewhere, Les Cowley's valuable old website can be found "frozen" here:

https://old.atoptics.co.uk/index.htm

For me, the strange site opened with the former URL looks as if it was hijacked by an AI bot, too.

Kind regards

Elmar

[Nicolas Rossetto]

Hello there Elmar,

For sure it is, I agree with what you are saying about quality of contribution.

For the old website version, I ran into it 2 weeks ago, because I kept looking for specific information and because I was not resigned to let it go, as it has been my main source of understanding of so may atmospheric optics.

In France, we too have one topic open on a meteorological forum, but the main contributors almost stopped to write for some personal reasons I can understand.
I know the two website you mentioned earlier but they are not active anymore and it is really hard to find some fellow countrymen to talk to on this matter nowadays.

This is also why I come here for almost 10 years now, and to wake a bit up my old german langage skills, at least for reading/understanding, as writing is still too difficult for now to me to express ideas correctly on such optical matter.

By the way, since you are around for this topic, Elmar, have you read the one where we discussed a bit about 13° halo with Karl und Carl (viewtopic.php?f=2&t=61581) ? I think you might have been in the discussions 10 years ago when the formation of 13° halo was in question. Do you know if this question has been answered since then ?

With my best.
Nicolas, from Jura

[Carl Herzog]

Hi Nicolas,

that's also the way I configured Halosim. But when I have the pyramidals with 1 degree of dispersion, the other lateral arcs are also extremely pronounced, and that does not match my images. When I use 12 degree of dispersion things look more in line with my images, but then P23 is nearly invisible. Using Ray Filters I can get a standalone bright P23, but I am not sure this matches a real life situation.

What Nicolas Lefaudeux describes is exactly what I do with my allsky camera setup. It's great for statistic evaluations and for monitoring in realtime, but it has the "disadvantage" that you don't miss halos anymore, and they happen more often than I previously thought. And when you know a halo is visible, there is no excuse not to additionally setup the DSLR.

Regarding reflections: some of them (typically the ones inside the circular fisheye lens) have advantages, as they are orthogonal to the horizon. This greatly helps manually aligning images without blurring the halos. Without the reflections, it is difficult to find the overexposed sun center and the zenith in the images (to get the shifting and rotation correction when aligning). So, reflections are not all bad.

Cloudy Skies, Carl

[Elmar Schmidt]

Hi Nicolas,

no, I am not in that game about very odd radius halos. I always thought: if the Finns haven't seen them, they are not there.

http://www.haloblog.net/author/submoon/

So, I always held it to be appropriate, that the ruling halo nomenclature should be in Finnish. Go for it, Carl

https://tiedekirja.fi/en/halot
https://urfu.ru/en/news/43164/

In the second link, you can download the PDF of a 2022 paper with an inventory of 119 known halos!

---

"Classical" pyramidal halos I only have seen once 2010 in Virginia (seen in my avatar; the photo blog here has been corrupted due to Dropbox changing its file sharing method later). It was a spectacular display, though, with 9, 18, 20, 23/24 and 35 rings evident on single shots with chemical film, already. There were 9, 18 and 23/24 plate arcs, too.

I admire Carl's work as of recent, which matches that of Nicolas Lefaudeux, the more so, as he is a relative newbie here. Both have shown, that pyramidal halos are hidden in our skies more often than previously thought of.

Kind regards

Elmar

[Nicolas Rossetto]

Thank you a lot for the link to this paper, I did not know it was available online so simply. What an incredible source of information!

For the fact I though that you were in "that game" as you said, indeed your avatar might have lured me into that thought.
My mistake then.
I see the 13° is in the 98's South Pole display. I hope we may find out more about its formation.

For the occurrences of odd radii halos, indeed, they are more often in the sky that seen or catch without stack processing, since most of them are not really sharp (at least not sharp enough or bright enough to see them with unaided eyes). But I had the chance, in the last 4 years, to get at least one sharp odd radius display, well visible before picturing it, and be able to burst with my camera to record/stack/process them, and kept the raw files in case of need after, with better rendering technics.

Furthermore, the 9° halo is the more common of every odd radii halos I see. Most of the time, in regular displays, it is the only odd radius halo in the pack.

I'm looking forward to read you guys in the forum and share some pictures with interesting displays.

Salutations distinguées.
Nicolas R.

[Elmar Schmidt]

Thanks, Nicolas,

I grew up in "Leica Town" Wetzlar with chemical film cameras,* and although converted to digital a good dozen years ago, never did anything like RAW image processing, stacking, R-B etc.

My specialty is in lunar eclipse photometry and a few related fields, but as a scientist I feel obliged to share information, references, and insight for other topics as well.

Kindly, Elmar


*As late as 2007, it once made my day, when a Harley-Davidson motorcycle rider on an epic trip in Hawai'i gave me a thumbs-up at a scenic overlook, after he heard me push the trigger of my OM-2 SLR, by saying: "Wow, mechanical shutter!"