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.

Subparhelia and sub 120° parhelion on ice surface

average stack of 15 frames

In the morning after new year's night, I noticed through a window cirrus clouds, and I went to observe. While I was waiting for the appearance of halos, I noticed weak subparhelia on the ice surface. Out of curiosity, I decided to look for a place where they could be brighter, and I found it (1, 2). It was quite a small area near a coast, almost all sides limited. There I saw not only bright subparhelia, but also clearly visible sub 120° parhelion in pillar form.

maximum stack of 3 frames

It was perfectly visible even when I did not move. The temperature was negative only at night until this morning. In the previous day it was positive (around +4 degrees of Celsius), as during of the observation (0...+1). 

At that time, while I was shooting halos on the ice surface, in the sky appeared parhelion and 22 degree halo (3). Later the upper tangent arc was spotted in cirrus clouds (on the stack also well visible supralateral arc - 4). At the end of the day, I also noticed weak and wide circumzenithal arc (5) from low sun.

Date: 2017-01-01

A distinct Wegener but other reflection halos from column orientation lacking

By Marko Riikonen

Spotlight displays are great in that almost every time you photograph them, you realize you understand halos less and less. This time the puzzle is: Why Wegener in the image above is so strong in comparison to other reflection halos? No subhelic arc is visible and neither there seems to be diffuse arc – I think the spikes at the subanthelic point are lamp artefacts. Of course I can’t not say that for sure, but around the subanthelic point even weak stuff shows up easily to the eye, so had there been diffuse arcs, I should have noticed it. If we accept this, then, in addition to the Wegener, the only suggestion of column reflection halos is what looks like a short patch of Tricker arc cutting across the sub-Kern arc (see the simulation below for comparison).

As for the posed question, I don’t have an answer. In simulations, using plate like column oriented crystals weakens subhelic and diffuse arcs in relation to Wegener, but they are still well visible, as shown by the simulation in the image below, which was done, I think, with h/d 0.3 plates.

Of the other stuff worth a mention in the image – which is a total of 27 min 20 sec exposure – is the sub-120° parhelion. It is quite common in spotlight displays, but to see it one typically has to run alonside the beam. This time it was clearly visible while standing still. There is also a blue spot. At 9 degree elevation it shares exactly the same location with 120° parhelion, which may be there too.

Another photo taken a bit later and at another location, shows a dark circular void at the zenith (or nadir, if you look from the point of view of halos), as shown below. A much more striking instance of this effect was captured by Jari Luomanen in 2013.

This night of halo hunt started on 8 November at 10 pm and lasted until 5 am. The development of the diamond dust quality was a slow and hopeless decline, which happens quite often when temperatures drop towards -15 °C. That is considered by halo hunters the worst temperature, giving crappy displays. Unfortunately the temperature notes were lost as my halo hunting diary got corrupted and shows now page after page ####s instead of letters. But I think it was between -11 and -14 °C through the night.

A plate spotlight display on 5th November 2016

By Marko Riikonen

Showcasing the last winter’s spotlight displays is still under way, but fresh produce is already coming in. Here is the new crop that I harvested on the evening of 5th November in Rovaniemi. In the image above the lamp is around -6 degrees below the horizon and both parhelic and subparhelic circle are visible. Slight intensity enhancements in them on the side of the sky opposite to the lamp are suggestive of Liljequist parhelia. Included are also Sub-Kern and sub-120° parhelion. I did not spot sub-Kern this time, but the latter was quite discernible when running alongside the beam. As usual, it was a pale pillar of light in which no individual crystals were detectable – very different from the intense subparhelic circle patch towards the subanthelic point, which is always made of pure glitter.

The display disappeared immediately when it got cloudy and there was nothing to be had for the rest of the night. What is not visible in any of the photos, but what was there many times during the display was the subanthelic diffraction pillar. Discovered by Marko Mikkilä in 2012, it is a quite basic feature in plate displays, but tends to come and go, never lasting long. So it is not necessarily captured by the camera unless you take it as your target.

The temperature was around -10 and -11 °C at the location. It is in a typical range of good plate stuff, not yet too cold.

The hiding sub-120° parhelion

By Jarmo Moilanen and Marko Riikonen

Nothing out of the ordinary here. Just a plate display and its crystals. Visible are the usual folks: subcza, sub-Kern, sub-120° parhelion. The behaviour of the last one in spotlight displays is a little curious, though: while it comes out well in photos, visually it is cryptic. One has to run along the beam to see that ghostly spot of sub-120°. It is not made of big glitter like the sub-Liljequist parhelia – it does not seem to be made of much glitter at all, just faint diffuse spot of light.

Rovaniemi, in the morning hours of 19th January.

Catching a divergent light halo effect predicted by simulations

Sometimes it is possible to make a deliberate attempt to photograph something predicted by simulations. On the night of 6/7 January we made such an attempt on the diffuse spots of light that in simulations are seen next to the divergent light subparhelion.

The effect is formed by a mixture of subparhelic circle raypaths, including 3157 raypath and sub-120° parhelion raypath. Its exact shape and position depends significantly on the crystal shape, like for the Liljequist parhelia.

To obtain an omnidirectional secondary light source that was bright enough we pointed the lamp directly to the snow surface. We took photos, looked at them more closely the next day, and there it was – those smudges of light predicted by simulations.

The photo above is actually from a slightly better case on the night of 18/19 January. Next to it is a simulation. Below is the one on the 6/7th.

Nicolas Lefaudeux / Marko Riikonen / Jarmo Moilanen / Marko Mikkilä

Subhorizon diffuse arcs with Liljequist subparhelia

Francesco De Comité took this great photo from an airplane between Brussels and Madrid in 7 August 2006 at 19h31. Unfortunately no more additional photos are available from this display.

There is really well developed diffuse anthelic arcs crossing subparhelic circle. Subanthelion point is illuminated by these arcs. In this case it is clear that there is no subanthelion, since bright spot on subanthelion point has clearly square shape caused by diffuse arcs. Column ice crystals have to have good orientation.

Other very rare halo shown in this photo is broader segments on parhelic circle on both sides on subanthelion point. Unfortunately these broader segments are not very clear and they are cutted by edges of the photo. These broader brightenings are so called Liljequist subparhelia caused by plate ice crystals. Liljequist subparhelia have been photographed earlier at least by Walter Tape (see Tape's book Atmospheric Halos in page 71). Tape's display is very similar than this Francesco's display.

Since Francesco's display has rare halo made by plate ice crystals, it would be a really good case to look for still undocumented 120° subparhelia. Hunt for 120° subparhelia is still going on...