Monday, 17 December 2018

Complex Halo Display, Borlänge, Sweden


On the 14th December 2018 at 12.30 UTC, Magnus Edbäck photographed an amazingly complex display in his home village of Utendal near Borlänge, Sweden comprising many extremely rare halos with at least one completely new halo form, a multiple scattering halo. Highlights include 46° contact arc, Hastings arc, extremely long Schulthess arcs and the rarely seen in daylight Ounasvaara arc. Like Marko Riikonen's 6th March 2017 Rovaniemi display, this one will go down in the annals of halo history and no doubt will be discussed and analysed for a long time to come. The two faint patches of light on either side of the 22° tangent arc are the new multiple scattering halo which at the time of writing has not been given a name. It is quite possible that the display was caused by snow guns in operation at the Romme Alpin ski centre situated about 12km away from Utendal.

Magnus has very kindly agreed to give an account of how he photographed the display.

"This is the story about my halo picture.

I was having lunch at my parents home when my mother asked me to look out to see how nice the sun was shining. At once I saw that this was not like any halo I had ever seen before. The sight of the sky was amazing. I then went to my home and grabbed the camera. My parents and I live next door to one another in Utendal, a small village outside Borlänge. I quickly checked that I had the appropriate lens, it was Samyang 14mm F2.8 that was on. The camera I used is a Canon 6D which I have modified with a Baader filter, mainly for use when I shoot the starry sky. From what I understand, the filter has no significance when shooting halo.

I went to a place on my parents courtyard where I could see as much of the display as possible. I quickly checked the settings on the camera, adjusted it to ISO200 and set the aperture to F8 to get a good depth of field. The day was quite cold (about 7 degrees below zero) and I was not wearing a jacket so I only took a few quick pictures (4pcs).

I then went back home to look at the pictures. On my way home, I also saw arcs to the north and I'm very sad that I did not take any photos of them. I quickly examined the images in Adobe Lightroom and picked an image that I uploaded to the Swedish astroforum www.astronet.se. I then went back to my parents to finish lunch.

Quite soon afterwards, I received comments on www.astronet.se by both Hans Bengtsson and Timo Karhula, who thought the display appeared to be something out of the ordinary. Hans thought I should send the image to Les Cowley and Timo thought I should publish it on www.taivaanvahti.fi. I received answers fairly quickly from both Les and www.taivaanvahti.fi. At 15:35 UTC 2018-12-14 I received mail from Marko Pekkola where he wrote:

"Congratulations Magnus of finding a new halo form in the sky in solar display! Several experts analysed this photo and Marko Riikonen identified one of the forms as the first multiple scattering halo of its kind.”  - Magnus Edbäck

Image processed by Nicolas Lefaudeux.
Image processed by Nicolas Lefaudeux.
Nicolas Lefaudeux has analysed and stacked the four raw files with background subtraction and produced these breathtakingly complex and beautiful processed images. The new halo is a multiple scattering [MS] halo, ie a "halo of a halo". These are extremely rare and can only appear in the brightest displays with very bright halos to forms.

This new halo is the uta of parhelion / parhelion of uta and it is the 5th MS halo form (after par of par, uta of uta, uta of pc/pc of uta, and cza of pillar). It requires both a very bright parhelion and a very bright uta to form. 

This uta of par/par of uta was the most likely MS halo form expected to be caught, because of its relative ease to appear in simulation and because it is not overlapped with other bright regular halos.

All images copyright Magnus Edbäck

16 comments:

  1. This is an incredible display. I love the sharp arcs from parry orientations and I love the sharply well-defined 46 lowitz arcs. I wished we had a ski resort in my area

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  2. Very nice! Hastings is "from" Parry sunvex! First observation?

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    1. There have been other observations of Hastings arc from convex parry including spot light displays near ski resorts

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  3. Is there a theoretical limit to the length of Schulthess arcs? These examples seem extremely long.

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  4. This is definitely a display to be remembered and studied for a long time. In Nicolas's processed version, there're even some hints of the MS tangent arcs taking their theoretical V-shape. Simply stunning.

    The intensity and quality of the Lowitz family in this display is striking as well. I'd like to add to Alec's question regarding the Schulthess arcs. When I try overlaying simulations on real photos, the position of the inner branch always appears closer to the 22 deg halo than in reality. In this Swedish display again I'm seeing the same mismatch. This topic has already been brought up by Marko last year: http://www.thehalovault.org/2017/03/trying-to-simulate-arcs-associated-with.html.

    Now a year has passed, I'm wondering whether there're any new theories/models which may potentially solve these puzzling cases.

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    1. Also the Ounasvarra arc and the sharply defined 46 lowtiz arcs too are amazing

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  5. I am not aware of any breakthroughs. Then there is also this one:
    http://www.thehalovault.org/2017/03/a-rovaniemi-display-and-simulation.html
    The arc does not touch the 22 halo while the simulated arc seems to extend to touch it. I wonder if a simulation could be made that just plots the full theoretical trajectory with no intensity taken into account. That would show whether it really is tangent to 22 halo, as it probably should be.

    The "fourth Lowitz arc" that Luomanen observed in lunar diamond dust display
    http://www.thehalovault.org/2017/04/lunar-display-with-lowitz-arcs-and.html
    maybe the same arc as in the display here.


    Marko Riikonen

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  6. A handphone video covering most of the sky has surfaced on Youtube: https://www.youtube.com/watch?v=ipF4wf6RsWs

    It appears that the Kern arc in this display was quite intense too. Impressive.

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    1. You can even see the slightest hint of Ounasvaara arc, too. Seeing Kern and Ounasvaara arc in sunlight display is just crazy.

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  7. Sweet bejesus! Because of the historical weight that Kern arc carries, this is news easily rivalling the MS halo. Praised be the videographer. It is the ultimate, final proof that Kern arc can be a naked eye object. So, the obvious question: did the guy take any photos?

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  8. https://twitter.com/amkatiwka/status/1075998157526294528?s=19

    Another video, unfortunately not covering much more than what already has been seen, but showing the 44° parhelion on the left.

    I don't know who took the video.

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  9. The rise of the number of good halo displays being captured and shared through social media is increasing rapidly and in my opinion, it is a double edged sword. On the one hand, at least the event has been recorded, but on the other, I wonder what kind of lasting record will remain in six months time, never mind five years, ten years or even longer? The documenting of halo displays is now out of the hands of so called "experts" and well and truly in the domain of the awe-struck "snapper". What will this mean? It will mean by and large, no RAW's, no stacks, and a great deal more "if only's"....if only the photographer would have taken this part of the sky or that part of the sky.... When we started this blog, I wondered whether there was actually any need for it in an age when everyone has access to the internet. I think this display alone underlines how imperative it is for archival sites like Halo Vault to exist and to continue to exist in the age of the 2 second attention span.

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  11. I was going through my mails and came up with simulation table that is related to the issue here:

    https://drive.google.com/open?id=1cf2qGQrasB-MMovGFrmPiliEr2thccs5

    I had send it to Walt in 2017. The mail texts explains the table:

    "Attached are simulations for 10 degree solar elevation. Six columns of different h/d. The three rows are:

    single scattering columns 30 mil rays
    MS columns 30 mil rays
    MS columns 30 mil rays + plates 10 mil rays

    I forgot to give the columns any prism face change, they are strict regular hexagons. Plates are a bit diamondish to give 120 parhelion boost at this low elevation. Aspect ratio variation was 0.1 for columns.

    In addition to the secondary parhelic circles we see parhelion-tangent arc and subsun-tangent arc pathways particularly in the lower right corner simulation."

    The software is Jukka Ruoskanen's HaloPoint.

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  12. I'm intrigued by the Kern in the last two images in the lower right of the frame. What causes the two parhelia like bright patches either side of the Kern? Are they parhelia or is their appearance just a coincidence?

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  13. Standard single scattering Kern from regular hexagons has these brightenings. Here they are less clear because I have probably allowed irregularity in crystal shape. And probably here is also MS Kern significant enough to smooth the SS Kern.

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