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.

Time Machine: High Cloud Hastings Arc in China, 2012.02.22

The Hastings arc is among the rarest of all halos, even more so in high clouds. On Feb 22, 2012, XU Guodong was blessed with an outstanding display in Mohe, and became possibly the world's very first person to photograph a high cloud Hastings arc.

The display started in the morning and lasted for at least two hours till noon. XU happened to be on a road trip thus unable to document the event continuously from a fixed location. Most of his photos were taken at two stages of the display, when the sun was at around 15° and 22° respectively.

During the first stage, the typical sun-side Parry elements such as the Helic arc and Tape arcs were not particularly strong. However, the Hastings arc was fairly prominent and very easy to distinguish in unprocessed images. Had XU been equipped with the necessary halo knowledge, he would've recognize the arc at the scene with naked eyes.

Early stage of the display when the sun was at around 15°. 4-frame mosaic. Slightly enhanced. See if you can spot the Hastings arc.

Background subtracted version of the mosaic. The Hastings arc stands out nicely.

The original image to illustrate how prominent the Hastings was.

The display remained strong as the sun rose to 22° elevation, when XU made the second stop of his road trip. At this stage the Tape arcs improved a bit while the Helic arc disappeared. The Hastings arc, together with the Wegner arc, somewhat weakened but was still easily discernible in unprocessed images.

2-image mosaic. Slightly enhanced. Sun at around 22°.

Background subtracted version. Though weaker than during the first stage, the Hastings extends further towards the sun.

While the sky around the sun was jam-packed with great stuff, the opposite side was also very busy. The highlight absolutely goes to the loop-shaped Tricker arc. XU was very impressed by how the loop gradually shrinks in size as the sun rises.

Tricker arc (probably some Greenler and Trankle too) during XU's first stop. Sun at 15°.

Tricker arc during XU's second stop. 3-image mosaic. Sun at 22°. Note how the faint Subhelic arc goes above the 120° parhelia and then touches the upper end of the Tricker loop. The blue spot is quite strong too.

This display bears great significance in China's modern halo history. 10 years have passed and it still is unchallenged, and will likely remain so for a very long time.

Jia Hao

Odd radius display on sunset time, 2022-10-16 (Jouhe, France)

Often, when I see the clouds coming from west, I try to do a high cloud sunset to see if there is something to see (like sun pillar and sunvex halos).

this day, we had mosly contrails making here and there some ice halos from my position, but nothing unusual to catch the eye (furtive sundogs, 22° halos, upper tangent and maybe Lowitz buddies but too short in time to be exploitable) (Time-Lapse of part of the day in here, South-South-East Field of View). To find other halos at sunset, the exercice can be tricky, as the global backgroud turn progressivly to yellow then orange so the b-r rendering is more complicated, with adaptation to make in the last 30-45 mins before the end of sunset.
As I don't have automatized this, I find myself resigned to make one setting for the whole sequence to save time in my processings.
And sometimes, something catch my eye, as it did this last 16th of october, last year.
The three next images show 3 differents times of the event, with slightly different processings:

2022-10-16-[17h14à18h58]-NNW-bw-v1-[4-2]-UsM-(49)-5s5-histo-UsM-h20-h28?-h35

2022-10-16-[17h14à18h58]-NNW-bw-v2-[4-2]-UsM-(47)-7s7-UsM-histo

2022-10-16-[17h14à18h58]-NNW-bw-v2-[4-2]-UsM(56)-6s6-UsM-h28?-histo


If needed, I can provide the bw sequence, so you can see (as I do with VirtuaDub) the evolution of the display and distinguish the 28° halo with dynamic (back and forth) play on the sequence.

A sequence you will be able to see there (Version1 & Version2), but with the compression due to GoogleVideo. Again, all raw images are still in my possession, as I guess I might not be done with this display yet.

Sharp Lowitz & Parry display, in short time [2023-04-04]

Here are some nice ice halos at the passage of a particular layer of clouds, during a clear sky day (2023-04-04, from near Dole, Jura, France). This clouds layers gave an extraodinary sharp looking display of ice halos, as I rarely saw in 15 years of watching. I was then in the good spot at the right time, for this one. While I was taking care of my lawn, during a clear sky day, I saw some high altitude clouds coming from the north, and decided to take the bet I will have some ice halos, but I did not epected that kind of sharp halos. In all the below images, clouds are coming from the left (North-East).

On this first stack image, you can see the Wegener arc, with almost the part crossing the parhelic circle. There is also the 120° parhelion with reddish edge as well as on the circle.
Process is (as an example of how I do usually, for the image shown above,
named 2023-04-04-[14h57to15h37]-bw-[4-2]-UsM(11)-5s5-notrack-UsM.bmp):
→ B-R ( -bw ) rendering of all the images of the sequence ( -[14h57to15h37] ),
→ 11th stack ( (11) ) of the sequence with 4 images ( -[4 ),
→ then Unsharp mask on this stack ( -UsM ),
→ then a new stack (with Registax, without the track on the sun ( -notrack ))
→ of 5 ( -5s5 ) of last stacks (those ones taken every 2 images ( -2] ))
→ then one more Unsharp filter ( -UsM ) to end it.

Later, like 5-6 minutes later, the layer of clouds enter the 46° FoV from the sun, which gave the most impressive part of the display to me.

Here is one single image, with just B-R rendering (no UsM or what so ever).

Then 2 stack versions witht this image along with some before and after, to see more clearly the Lowitz & Parry display, (on the above one, we can see parts of 46° halo, but not in whiole, because of the hole in the clouds crossing the view... I guess)

and with the images when the clouds are on the side of the sun from my point of view. I even manage to watch clearly the circumscribed halo while i was cutting my lawn.
You can also see the left part of lower Parry arc tangent with the circumscribed halo.

A last part of the display, with clouds on the bottom left of the sun, to see the extension of the lower Lowitz and the extension of the left part of the Lower Parry, tangent to the circumscribed halo.
For this stack, a "min" function is applied during the stacking process, in order to keep the minimum value of each pixel while stacking, and try to make the black forms therefore the colored halos more visible.

A crop on the left sundog, to see the Lowitz crossing and the 2 Parry arcs.

I have not presented any colored versions, because of the heterogeneous form of the clouds mask the halos for this display.

Finally, a time-lapse of the display is available here, which a compilation of differents time-lapses (one for each processing type). From those images are extracted the previous posted here :
www.flickr.com/photos/gaukouphoto/52808574767/in/dateposted/

All images are taken with Canon EoS 6D + 8mm Samyang lens from my roof windows, South-South-East side.
Settings: 1/1000s, ISO100, f/9,4, 1 image every 12s.
Sun mean height is 47° at the time of the sequence.

Google Drive folder shared, with all the images presented here, and the time-lapse.
I still have all the raws of the sequence if needed too.

Odd Radius Display Including 13° Halo, Vilnius, Lithuania 18th March 2023

The display occurred on 18 of March and I observed it from Vilnius, Lithuania.

For the whole day, cirrostratus clouds covered the entire sky. The clouds were moving eastward and also sublimating.

I started observing at 10:25 EET. At that time there were already odd radius halos present: with the naked eye, you could definitely notice both the 9° and 18° halos.

At 11:45, only the 9° halo was present, and at 12:00 the odd radius halos disappeared. After that, and until around 17:00, there were a faint 22° halo and tangent arc visible.

I photographed the halos in raw format with a DSLR camera. After enhancing the images, a 35° halo became visible, but I was surprised the most to see a ring between 9° and 18° halos, which appeared to be a 13° halo. After sending the images to The Halo Vault, I got a confirmation about this from Nicolas Lefaudeux and the Halo Vault team.

Here are some pictures from the display, last two of them in the sequence were processed by Nicolas Lefaudeux:

(All images copyright Donatas Gražulis)

(Image processed by Nicolas Lefaudeux)

(Image processed by Nicolas Lefaudeux)

A similar feature appears in an older photograph that I took on 25 of June 2019. This is the only photo from that day that this appears in; it was taken with a phone:

- Donatas Gražulis

Unusual Elliptical Halos May 8th 2022 in Japan

On May 8, strange elliptical halos were captured by Pipibun in Kunimi, Fukushima prefecture, Japan.

At 14:30 that day, there were cirrus and cirrostratus clouds in the sky, and some frequent halo forms appeared. After taking pictures for a while, the observer moved about 20 km to the north. 

At about 16:10, looking at the sky again, altocumulus clouds over the sun and the double elliptical halos appeared above it. The display lasted for 20 minutes. With the sun 23-26° high, major axis of outer ring was about 10° and minor one was 5°. 

The shapes of the elliptical halos are varied and are thought to be affected by apex angle of the flat pyramidal crystals (or possibly dendritic snow-type crystals.) Additionally, they are known to become sometimes multiple and inner rings are basically similar ellipsoid. Therefore, were there at least two different gradient responsible crystal groups in that sky?

Double (possibly triple) CZA in Zhangye, China

Finally, double/triple CZA, a.k.a the Jensen arcs ( https://thehalovault.blogspot.com/2020/04/new-halo-triple-cza-jensen-arcs-in.html ), made a debut in China. On Sep 27, LING Xiaoyun caught them with her iPhone in Zhangye, Gansu province.

Captured at 09:20:14 UT, when the secondary CZA below the main one was most prominent. Sun elevation 20.0°.

Captured at 09:21:16 UT. The secondary CZA had somewhat faded. Sun elevation 19.8°.

The secondary CZA is also visible through the ultra wide lens.

Catpured at 09:19:33 UT. Sun elevation 20.2°.

She even managed to grab a super close-up shot placing her iPhone behind a pair of 10x50 binoculars.

Captured at 09:20:44 UT. Sun elevation 19.9°.

When enhanced, a third CZA pops up above the main CZA in some of the close up shots. There's also the slightest hint of a fourth CZA below the secondary CZA.

The 09:20:14 UT shot processed. USM above, USM + BGR below.

It should be noted though modern smartphone data are prone to artifacts introduced by HDR and other algorithms, so processed results should be taken with a grain of salt.

Assuming the third CZA above the main one is real, it can be explained by some new models proposed after Jensen arcs' discovery.

Diffraction model:

Nicolas Lefaudeux suggests that the Jensen arcs would be caused by diffraction through prism faces of thin plates. For this to happen, the crystals need to be both thin and have homogeneous thickness. It is the same physics as diffraction through a slit and diffraction corona around the sun.

Because of the combined effect of the dependency of the diffraction with wavelength (longer wavelength diffracts farther) and color spread of CZA, it creates clear arcs below the CZA.

Above CZA, depending on the crystal size, it can be quite a white glow or very washed out arcs. About arc distance below CZA, it is directly linked to crystal thickness.

Below is a simulation made by Nicolas with ZEMAX software (applying some diffraction properties to the prism faces of the crystals).

Thick plates with flat pyramidal tops model:

JI Yun proposes that thick plates with flat pyramidal tops could create extra CZAs above and below the main one. Below is his simulation with HaloPoint. An apex angle of 177.2° is adopted for the pyramidal top.

As far as we know there're also other new models in the works. Now that we have four sightings of Jensen arcs within two years, it probably won't take long for us to have enough cases to verify which theory wins out.

Jia Hao