Sub-Liljequist and probable 'sub-Liljequist Blue Spot' in high cloud above China

 

The sub-Liljequist 'Parhelion' in high-clouds is rare. On August 14, 2025, a user '太平洋蓝藻'(ID: 516836436) from ' Bilibili.com'(a polular vedio website of China) captured the first record of this event in China during a flight over the Yellow Sea. the sub-Parhelic Circle and sub-120° Parhelion were captured at the same time.

What makes this particularly remarkable is that on left of sub-Liljequist 'Parhelion' in the photograph shows a distinct blue tint, suggesting the possible presence of 'sub-Liljequist Blue Spot'. Pinson HUANG from the Chinese halo watching community was the first to identify this possibility and made the initial simulations. I refined the simulation parameters based on HUANG's work, and the results showed a good alignment with the photograph. SUN Hao Xuan(孙浩轩) and Jing Xiang from the Chinese halo watching community assisted in image authorization and joined in the related research process. KiloNova(千新星), SONG Xi Pei and QIAN Kun from the same community provided crucial information in the analyses of flight data and lens characteristics.

 

The photograph was taken at 16:43:26 (UTC+8). Based on the CZ5855's flight information(N37.96, E122.98) retrieved from https://flightadsb.variflight.com for that specific time, it can be further concluded that the solar altitude was 22.3 degrees.

The unevenness of cloud layer should be considered as the cause of the unevenness of the sub-PC, but some simulation results quite support the existence of the sub-Liljequist.

Halos of Venezuela

South America is pretty much a blank slate what comes to halo enthusiasm, so it is encouraging when we got contacted from Venezuela by Franklin Fernández, who had written an article presenting the best displays captured in his country. Judging by the random big displays that have popped up from different corners of South America over the years, there is reason to think the continent as one of the better areas for halos, and now the Venezuelan displays Fernández has scoured from the internet add credence to this notion.

What is more noteworthy is that the best displays are concentrated in the western part of the country which is where the Andes mountain chain ends. This gives more weight to what some of us may have already thought, that the curse of the equator is cancelled by the Andes. Unlike in the Philippines where I have been observing, or Singapore of which halo scene I have heard from Jia Hao, all-sky displays must be a regular occurrence along the tropical segment of the Andes chain and presumably sun pillars are not such rarities either. And we don't know what kind of odd radius jewels there might be lurking as these shows don't tend attract so easily the attention of the uninitiated.

Franklin's article is available in Academia.edu and Scribd. He will keep adding displays to it as they come and says the document has already created buzz. Could this be the start of Venezuela and eventually the continent's other Spanish speaking countries waking up to halos? All prospects are that a dedicated observer, in particular along the Andes chain, would be in for reaping it big.

(The display above was captured by TikTok user danny3461 on 6 October 2024 in Macoa near the city of Machiques at the west of the country. In my hastily made stitch the parhelic circle is full despite the large gap on the right. The show was documented by a handful of other people as well. See also the impressive high sun display on X of an unknown date in Caracas)

A grand Bottlinger's rings in diamond dust (2025-Jan-12, China.)

 A spectacular event of Bottlinger's Rings occurred on January 12, 2025, in Hemu(禾木), Xinjiang, China. For China, this was the first time the phenomenon was observed in diamond dust (rather than being captured from high-altitude aircraft). 'Javen嘉文儿', a user from the video website 'bilibili.com', directed his photography team to captured extensive footage. We are permitted to share the related files here.

vedio here

 

Footages show a solar elevation angle of 11 to 12 degrees. The lack of ice crystal sampling is regrettable, and it is hoped that valuable ice crystal samples can be obtained the next time such event occurs.

The original web link: https://www.bilibili.com/video/BV1jKKweuEQG/?share_source=copy_web&vd_source=e1764a76e81b36e4cb1d6f24f1f6a9ee

 

(We'd like to thank: Sufflection_, Jingxiang and Danyang(佩佩), for their assistance in related communication.)

High-altitude pyramid column arcs and kaleidoscope sky （6 May，China）

 Every year from March to May seems to be the pyramid column arcs' season for China. In the 2024 season, the most eye-catching display occured on 6 May, ChangSha, HuNan Province. At altitude of about 71.3°, the Pyramid column arcs, PC and Wegener crossed each other, bringing a spectacular picture of the sky.

(张晖)ZHANG Hui's stack image through a stack of 112 photos spanning 10 minutes. BGR and USM processes make arcs clearer.

Below are the results of a preliminary simulation using ZHANG Jia Jie 's program.

Well, now we are already looking forward to the second half of the year. Unlike March to May, June to August seems to be the peak time for pyramid plate arcs and 28° arcs for China. Please wish us luck.

JI Yun

Two below-sun Tape arcs in German Alps, 9 January 2024

by Lasse Nurminen:

 

One of the great things in the modern day observing is the possibility to explore the web for observations around the world. It gives just so much more to this hobby.

 

Once again I was browsing a German website´s forum (https://forum.meteoros.de/) about halos. There are several threads with links to halo displays visible in a network of cameras widely spread over the mountainous area in Central Europe (https://www.foto-webcam.eu/). In a post from Ruben Jakob (https://forum.meteoros.de/viewtopic.php?f=2&t=61705#p243845) one of the links at first looked like only a well formed infralateral arc, but something was disturbing me. Just as if there was a faint arc next to it, what could it be?

After a little thinking I thought it must be something related with the lower Tape arc/Parry infralateral. I took a couple of screenshots of the changing view with the available 10 minute steps and run them through a little Photoshop process to make the faint halos better visible. After that I had no other ideas but to let Mr. Riikonen to take a look at the situation in hands.
 

by Marko Riikonen:

 

Nurminen mailed me some photos of this 9 January 2024 display in Balderschwang, Germany. His hunch of something going on there was right. As shown by the title photo, two below-sun Tape arcs – one tangent to 46° infralateral arc and one to supralateral arc – are visible. The former is well established: although still a high rarity for any halo hunter to bag, over the years a representative collection of specimens have accumulated from ice fog displays. The latter is a much more furtive animal. It's been photographed in a couple of spotlight displays, but the only previous celestial light source record is the display that Herman Scheer photographed on 18 October 2010 in Sonnblick Observatory, Austria (https://www.ursa.fi/blogi/ice-crystal-halos/superb_diamond_dust_display_in_austria/). However, the 9.5 degrees sun elevation meant the two arcs were superposed, contributing about equally to the joint arc's intensity. And given in spotlight beam we have photos of only either lower arc, here is what raises the Balderschwang display on pedestal: it is the first record in which both arcs are visible individually at the same time.

 

The webcam took a photo every 10 minutes. The display started at 14:30 (title photo, sun 15.1°) and was seen until 16:10 (sun 4.4°) after which the sun got too low to shine anymore to the ice fog. At the end of the post the full sequence is shown. The most interesting stuff was in the first hour and above are three stages from this interval with (a bit wider angle) simulations using HaloPoint: 14:40 when the two arcs are distinct and nicely separated (arrows); 15:20 when they are already quite merged; and 15:30 when a practically perfect superposition is seen.

 

There are 8 arcs to this family, but normally we regard as Tape arcs only those that are solely made by Parry orientation. This reduces it to four arcs – two obliquely from the sun on 46° infralateral arc, two on supralateral arc – into which number also belong the two arcs in Balderschwang photos. As to the naming, the situation is unclear, at least on the level of individual arcs. Tape himself has used terms Parry infralateral and Parry supralateral (also some usages of 46° Parry by others can be found in the internet). But it appears that Tape only associated two of the four arcs with these names. If we look into the monolithic A General Setting for Halo Theory (1999) by Tape and Können, we see that while the other arc in the Balderschwang display would be called the Parry infralateral, the other one is "unnamed" (page 1581, left column, last paragraph). And given there have been really no serious suggestions stemming from the generic "Tape arc", the task of naming this quartet members appears to be still before us. As the arcs divide into above and below light source pairs, the names could play out like this:

upper Tape/Parry supralateral (arc)
upper Tape/Parry infralateral (arc)
lower Tape/Parry supralateral (arc)
lower Tape/Parry infralateral (arc)

However, because supra and infra are synonymous for upper and lower, there is a bit of the feel of those "logical monstrosities" that Tape writes about in the Nomenclature Woes chapter of his book Streetlight Halos (second part, page 170). Moreover, naming of any halos from double oriented crystals should be such that it takes into account also the corresponding arcs that arise from raypaths involving a reflection from horizontal crystal face and that's where the above suggestion again performs poorly by extending what are already quite long-winded names. What's the solution? Alphabet letters would seem to be one:

Tape A	81	✔️	+33...-27	27		counter-Tape A'	861		+33...-24	24	20...24
Tape B	71	✔️	-33...+27			counter-Tape B'	731		-33...+24
						counter-Tape A''	831		-20...-27	never
						counter-Tape B''	761		+20...+27
Tape C	15	✔️	+63...-3	3		counter-Tape C'	164		+63...0	0	0
Tape D	14	✔️	-63...+3			counter-Tape D'	135		-63...0
						counter-Tape C''	134		0...-3	0
						counter-Tape D''	165		0...+3
Tape E	31		+32...0	0		counter-Tape E	361		+32...0	0
Tape F	61		-32...0			counter-Tape F	631		-32...0
Tape G	16		+58...+90	never		counter-Tape G	163		+58...+90	never
Tape H	13		-58...-90			counter-Tape H	136		-58...-90

The arcs made exclusively by Parry crystals run from A to D. The two arcs in the Balderschwang display come out as Tape C and Tape B. Arcs E to H are better known as made by plate oriented crystals and include circumzenith arc and circumhorizon arc, but should these occur solely from Parry crystals I agree with Alexander Haussmann that they be recognized also as Tape arcs (Haussmann points this out, as pertaining to circumzenith arc, in the comments section of my post http://thehalovault.blogspot.com/2017/10/halos-on-6th-march-2017-in-rovaniemi.html). Perhaps surprisingly, these specific situations appear still undocumented.

 

The table is just a sample from one of alternative nomenclature suggestions for halos from double oriented crystals that I have been working on. While the lettered versions seem to me the best way to go with Tape arcs, the above sample is not necessarily my favourite. For example, letters could be assigned to each arc differently, such as running from the most common arc to the least common arc. This kind of ordering may not be so clear-cut for all halo families, though. If we would apply it to the Tape arcs in the above table, swapping letters B and C would probably get it right. I hope to get the nomenclature article done with and posted here some day.

 

None of the reflection arcs in the right side of the table corresponding to Tape A-D have been observed – yet. They don't come out well with regular hexagons. Triangular(ish) shape, which is common in ice fogs, is better as demonstrated by the HaloPoint simulations below, arrows marking the reflection arcs. These tentatively named "counter" arcs may get overwhelmed when they occur on infra- and supralateral arcs, but the good thing about snow gun generated ice fogs is that every now and then Parry orientation dominates: there are displays in which Tape arcs are seen without infra- and supralateral arcs (example: https://thehalovault.blogspot.com/2016/11/a-pure-breed-uppervex-hastings.html).

 

 

Of the two upper oblique Tape arcs we are all well familiar with the one that appears on supralateral arc, Tape A in the language of the table above. It is "the" Tape arc that accounts for the great majority of observations of the four arcs. The upper arc that is associated with infralateral arc, Tape D, has been observed only in spotlight displays. There is a reason for this: its light elevation range tops at 3 degrees above the horizon, rendering it improbably hard to see in solar and lunar displays. We have some representative photos of this arc (example: http://thehalovault.blogspot.com/2017/09/halos-on-night-of-1415-december-2016-in_30.html) but no particularly good co-occurrences with arc A. Looks like there are only two such displays. First was the halo complex that Marko Mikkilä, Jarmo Moilanen and I watched in Rovaniemi on the night of 23/24 November 2015 (https://www.haloblog.net/2016/10/25/major-spotlight-display-possible-4th-tape-arc-component/). The second is this winter's crop, a display that I photographed on the night of 10/11 November 2023 in Rovaniemi, shown below as two versions of a 11x15s stack (arrows mark Tape D) and a simulation. The two upper arcs in these displays are the corresponding arcs to the lower arcs in Balderschwang display, but in swapped positions due to light elevation difference. By the standard of Balderschwang, lightsaber wielders still have their work cut out to capture a better defined instance of the upper pair.

 

 

An attempt at high cloud 44° parhelion

High cloud 44° parhelion is still waiting for its capturer. A chance to try for one came on September 28 this year in Kontiolahti, Finland, when a cirrus floe containing a short-lived blinding parhelion moved out towards the appropriate position.

I had already camera snapping photos at 10s interval, but changed it to 4 seconds when I estimated the leading edge of the floe had reached about 44 degree distance from the sun. The b-r image above is 84 frame stack from the time it took for the floe to pass the 44-46 degree azimuth and shows indeed a dark spot indicative of red color. But it looks to be too far out for 44° parhelion when compared to the 46° halo in the image. Probably we are looking here just at a segment of 46° halo or 46° lateral arcs crossing, or both, but proper measurements using starfield may still be worth doing. 

Even if the result seems negative, it thought to share this to pay attention to situations where high cloud 44° parhelion might be a prospect. Below are other relevant images and some more info.

Bgr and usm versions.

At 13 degree sun elevation 44° parhelion is inside 46° halo, which is not the case with the spot in the observed display. The other half of the simulation has column and Parry population as the display had halos also from these crystals. Made with HaloPoint.

The short stage during which bright parhelion appeared in a cirrus floe. Photo interval is 10s.

Here is shown the first (top) and last (bottom) photo of the 84 frame stack (middle) from the period that it took for the floe (delineated) to pass 44-46 degree mark.

Uncropped versions of the 84 frame stack, br and usm. Notice the lacking of uppervex Parry. With regular hexagons at 13 degree sun it should be of equal brightness with the uppercave. In stacking, when sun is tracked at this solar elevation range, uppervex gets unfocused and uppercave focused relative to each other due to their sun elevation dependent movement which are in the opposite directions. But as the stack has only 0.5 degree sun elevation change (from 13.3 to 12.8 degrees) the effect should be negligible. Thus the absence of uppervex (or almost absence, there seems to be a ghostly suggestion of it in the image) tells of tabular crystals. A simulation with 0.7 1 1 0.7 1 1 shape modified crystal in HaloPoint reproduces the situation and this is what has been used in the simulation above (0.2 uniform deviation for the two faces). If somebody knows other similar Parry displays showing evidence of tabulars, I am happy to hear. I think I knew one, but have forgotten about it.

In Germany they had this display much better:

https://forum.meteoros.de/viewtopic.php?f=2&t=61567&sid=b6b52b267d966f7de49207b4e6863089

https://forum.meteoros.de/viewtopic.php?f=2&t=61570&sid=d1f3268f300beb1ff746ae83a13af46e

Marko Riikonen

Simulation-like 18° plate arcs and puzzling 22° arcs from airplane, China

On May 24, 2023, I witnessed a very high-quality case of 18° plate arcs while onboard a flight over Southwestern China. Due to my busy work schedule, it took me nearly two months to review and analyze the batch of photos I captured. Clearly, there were more surprises contained in them.

The 18° plate arcs are common in China (in the southern region during the summer), but high-quality occurrences are rare worldwide. In recent years, Chinese sky enthusiasts have explored and contributed numerous images of 18° halos. Some were quite bright, but without exception, they were all quite blurry, likely due to wobbly crystals and diffraction. Blurriness of these arcs might be a common feature since, in previous cases, they are almost always accompanied by the 23° plate arc, indicating the presence of thicker ice crystals, which may have difficulty maintaining low tilts in crystal orientations.

Therefore, when I witnessed this pair of remarkably clear V-shaped 18° plate arcs, I was surprised that such small tilts even exist under natural condition. The arcs were amazingly bright, outshining all other halos minus the sun pillar. In fact, I only noticed the 18° plate arcs and the sun pillar with my naked eyes. Other halos in the display were all picked up later photographically.

(The display lasted for less than a minute, during which I managed to capture six photos. In hindsight, I regret not taking more photos by tolerating the glare and adjusting the shooting angle less frequently to avoid reflections from the aircraft window. However, with the limited six photos I have, I was able to align and stack them to obtain a more complete halo phenomenon. Taking more photos might have further enhanced the final result.)

6-frame stack. Solar altitutde 9.8°.

Now let's move on to the other halos in the display. The lower 20° plate arc and the lower right 24° plate arc are clearly present in some of the photos. The 9° plate arc appears to be absent. In simulations, one can invoke nearly triangular ice crystals to weaken the arc till it gets overwhelmed by the bright sun pillar. However, it's also possible that the absence of the 9° plate arc is due to uneven distribution of ice crystals since the lower left 24° plate arc never showed up. The 35° plate arcs appear strong in simulations, but they were unfortunately obstructed by the wing and engines during the display.

What caught my attention even more are the arcs at the 22° positions. Initially, I thought the pair of tilted arcs outside the 18° plate arcs were 22° parhelia, distorted due to wide-angle lens effects. However, simulations show that the 22° parhelia should be closer to the sun and shouldn't tilt to such an extent.

So, what are these tilted arcs in the photos? They are neither regular crystal halos nor something generated by (3 0 -3 2) exotic crystals or cubic ice crystals. Their presence perplexes me.

B-R, BGR and other post processing work indicate these tilted arcs are actually the brightest spots on a pair of much longer, vertical, slightly sunvex arcs, resembling the appearance of the Lower Schulthess Arcs, also known as Lower Reflected Lowitz Arcs or Subparhelic Arcs.

BGR(background removed) version. 

B-R processed version. The vertical extent of the arcs becomes clear. Segments of 18°, 20° and 24° halos can also be seen.

The behaviour of Subparhelic Arcs/Reflected Lowitz Arcs/Schulthess Arcs has been a long-standing issue. It seems challenging to explain why they mostly appear as single or double arcs, rarely as triple arcs as shown in simulations. But in this case, there is an additional puzzle: why do these arcs have significantly enhanced bright spots near the 22° parhelia position?

I don't want to explain all the discrepancies with simulations as "uneven clouds" or other coincidental factors. During the one-minute long display, it remained remarkably stable - the Lower Schulthess Arcs/Lower Reflected Lowitz Arcs/Subparhelic Arcs were always present, and the aforementioned 22° bright spots were also consistently there, even though the clouds had undergone some changes.

I wish to hear the opinions of fellow researchers worldwide on this matter. I am hesitant to claim it as a puzzle, but I am not exactly sure what mechanisms created these arcs. After initial attempts at simulation, I found that Lowitz raypaths 8-2-1-6 and its multi-reflection derivatives such as 8-2-1-2-1-6 etc. produce a pair of arcs that resembles what I saw. If we artificially disallow conventional Lowitz raypaths and allow only the above mentioned multi-reflection paths, then Lowitz-oriented plates with moderate tilt such as 15° produce a relatively ok match. (Compared to the odd radii in the photos, the match is much poorer. Lowitz arcs' mismatch with simulations has been a long-standing issue and it seems this case is no exception).

Simulation showing only the Lowitz raypaths 8-2-1-6 and its multi-reflection derivatives such as 8-2-1-2-1-6 etc.

Comparison between the simulation and the real scene. Not the best match, but close.

To explain why only multi-reflection raypaths are present, it might be speculated that the ice crystals are extremely thin. Nicolas Lefaudeux's '100 hit' theory inspired me. Perhaps certain extremely thin plates allow for multiple internal reflections between basal faces, creating the observed halo while excluding the usual Lowitz arcs.

However, explaining why only Lower Schulthess Arcs/Lower Reflected Lowitz Arcs are present, and not the upper and middle ones, is much more difficult. Perhaps a specific mechanism exists that gets the Lowitz oriented crystals azimuthally locked so that its face 6 faces the observer, while still allowing the main axis to azimuthally rotate within a limited range of angles, thus selectively producing these two arcs? (Fully locking the main axis cannot produce satisfactory arcs. I have tested this). If such a thing is possible, this pair of arcs might deserve a specific name to distinguish them from Schulthess Arcs/Reflected Lowitz Arcs/Subparhelic Arcs. However, I still feel this is a far fetched explanation since there is no available literature indicating the existence of such a 'alternative' Lowitz orientation.

As I haven't obtained the posting access to HaloVault, my colleague JIA Hao has kindly helped me translate and post these observations (originally in Chinese). Also special thanks to ZHANG Jiajie for having multiple fruitful discussions with me on this topic. We look forward to more excellent explanations from the global community. 

JI Yun