Some odd radius column displays from China in 2018

Odd radius column arcs have long been deemed as some of the rarest halo forms. Sighting reports in most parts of the world have indeed been sparse. However, during the past few years in China, we came across a good number of odd radius column displays. Spring monsoon seems to bring them to our country every year.

In 2018 we documented at least a dozen such displays country wide, most of which occurred in April and May over Southern China. Here I’d like to share with the world some of the most noteworthy ones. All photos below are single shots with only minor USM applied.

On April 29, photographer Cui Yongjiang witnessed a long lasting display from Shangri-la, Yunnan Province. Complexity of the display peaked in the afternoon when the sun dropped to around 40° altitude. The 9° and 24° column arcs in this display are rather weak, implying short prism faces among the crystals.

© Cui Yongjiang, shown with permission

Later on May 17 in Sanya, Hainan Province, Weibu captured a short-lived display in which the sun sit at 83° altitude. At such high altitude, most odd radius column arcs turn into circles. The 20° and 35° column arcs have their upper half much brighter than the lower half. The way that the 20° column arc completely outshines other arcs in this display is quite interesting. Crystals with long pyramidal caps and very short prisms might have been responsible for such appearance.

© Weibu, shown with permission

Up until August, all documented column displays took place in Southern China. Such displays have been much rarer in Northern China where monsoon from the Indian Ocean hardly reaches. 

The pattern does get busted sometimes. On August 12, the best display of the year swept across Heilongjiang Province in Northern China. Middle school teacher Mao Xiufang from Daqing noticed this complex display during class break and snapped this amazing shot with her phone. The 20° column arcs in the display are sharp while the 35° column arcs are vividly colored. The 9° column arcs are even displaying their theoretical curly-bracket shapes.

© Mao Xiufang, shown with permission

An hour later, the clouds advanced 200km east with crystals reaching their peak diversity and optical quality. Fang Tongbing grabbed this handphone photo manifesting the display at its best. The sharpness of the 9° , 20° and 24° column arcs are very close to simulations. Had the crystal quality been any better, we might even start seeing traces of odd radius Parry arcs! 

Apart from the column arcs, some plate orientated crystals also joined the party contributing to a weak 23° upper plate arc.

© Fang Tongbing, shown with permission

This high quality display turned out to be the last odd radius column display from China in 2018. Overall we had a big year for odd radius halos. Interestingly all these displays occurred close to noon hours when the sun was higher than 40°. The cause of this pattern could be a meteorological subject worth studying.

Hopefully in the year of 2019 we will be blessed with more displays like these. Stay tuned.

Jia Hao

Recent displays from St Petersburg, Russia

In this post, I'm including the most interesting displays observed during the last month.

14th March 2017

On that day, halos appeared in the morning in separate cirrus clouds. Their arrival was not predicted by the meteogram. When I looked out from the window, I saw a bright CZA, but when I came down, it had disappeared. Nevertheless, I could see the weak supralateral arc. Half an hour later, I also saw a nice infralateral arc, when the cirrus cloud reached the horizon.

29th March 2017

In the evening bright parhelion was detected, and then a little while later also the wide circumzenithal arc. The halos were produced by the anvil of a convection cell.

1st April 2017

In the morning, at 10-00, the sky was clear. But in the south-west direction, low over the horizon a lot of cirrus clouds were visible. Their arrival was extended for an hour and a half. When a border of a front of cirrus clouds started to arrive, I noticed that it was weak and almost transparent. When these weak clouds reached the sun, at first I did not notice any halos. But soon, some markers of sub-visual odd radius display appeared.

It was broad and undefined halo in 22° area, with pretty obvious upper 23° plate arc in some moments. In the reflection of my sunglasses these things were visible a lot better. These weak odd radius halos were visible for around a half of hour, or even more while the area of weak cirrus crossed the sun.

Then, on the right-hand side pretty bright 22° halo started to appear. It was the arrival of main part of cirrus. In that area clouds were common and solid. After few minutes both bright tangent arcs appeared. Lower tangent arc was brighter than upper. I also noticed big infralateral arc on the right-hand side. It was pretty weak, but well coloured. I could see the arc better when I used peripheral vision.

This peak of the display was rather lengthy, and during its course I also watched both 120° parhelia, parhelic circle (it was easily seen within 22° ring), and the top part of 46° halo (likely it was the combination of supralateral arc and 46 halo. Although both were weak, together they became visually visible).

The peak was interrupted when middle-level cloud started to arrive. Then I saw a couple times only bright 22° halo

7th April 2017

The display looked quite ordinary, so I was glad I detected pyramidal halos such as upper 23° plate arc and 9° column arc.

9th April 2017

On that day, there was only a weak 22° halo. But the stack discovered also 18° halo/18° plate arc

10th April 2017

It was the weak display, which lasted most of the day. There was no suspicion that there may be pyramidal halos. But still I got upper 23° plate, 18° plate arc and 9° halo in the stacks.

The great 24 February 2017 halo display in Pskov region of Russia

In the evening, I looked at meteoblue's meteogram (like I do everyday), and saw on it plenty of high-level clouds, but at the same time together with middle-level clouds. At 09-30 I woke up that to check whether middle clouds would not allow observing halos.

I came out and saw that the sky indeed was pretty dirty and contained not only cirrus but also low and middle clouds. But above the sun were the central part of UTA and diffuse pillar. I could leisurely to prepare my camera before halos became brighter.

After a few minutes, UTA became seen pretty well. Viewing the sky I was very surprised to detect the supralateral arc to the left of the sun. The arc was not bright but it was clearly visible. It was weird to see such good halos in such dense clouds. Clouds from different levels merged with each other. So at first, I did not understand that it was a big display that penetrated through the gaps of the lower clouds.

After 10-15 minutes came a big gap in those clouds and I saw the full Supralateral arc which was noticeably brighter than previously. I already was very glad because the arc in this form I saw only on my screen when I processed stacks. And at the moment I saw it in the sky with my own eyes. However, this was only a prelude of what was to come.

Wegener arc, subhelic arc, and blue spot on parhelic circle

Around 11-00 the sky started to clear and above the supralateral arc and a nice circumzenithal arc appeared. In that moment I noticed to the west a bright fragment of the parhelic circle which was low over trees. Cirrus arrived from this direction. While I changed the direction of my camera's field of view, I noticed also the anthelion. High clouds arrived quickly, and they were very uniform and smooth. The brightness of halos quick started to accrue. I ran in my home in order to show the current display to my father, and during this couple of minutes the brightness of halos increased even more. I ran back to my camera, and in this moment halos became extremely bright! The upper tangent arc was very perfect and sharp. The supralateral arc was brighter than a common primary rainbow! Probably it reached such extreme brightness not only because crystals were perfect, but also because the sun elevation was almost optimal. The parhelic circle was also incredible and looked like jets of light. Wegener arc was visually visible as well. Its oblique wide lines pointed out on far and weak anthelion. Around anthelion from time to time X-shaped arc was visible.

Near sun there are 9° halo together 9° column arcs

All sky view. Near anthelion there is Tricker arc

Anthelion and some of diffuse anthelic arcs

Upper tangent arc with diffuse upper 23° plate arc and sharp 24° column arcs. Thanks to M.Riikonen for the confirmation

Halos lasted in this bright form around 45 minutes. After the brightness of complex a few decreased, but all details continued were visually visible. I remember that I saw well crossing of Supra/Infra-lateral arcs on the parhelic circle. Also from time to time appeared 120° parhelia.

On the left there is 120° parhelion

At 13-10 was the end of this great display, only halos near the sun remained. Parhelia were most bright in this moment and seemed to me that near them were Lowitz arcs. But stacks showed that is not true.

A spring-starter in Finland

On 25th March a relatively small high-cloud area swept over Southern Finland and produced a fine halo for observers in Helsinki, Espoo, Turku and Riihimaki. In Riihimaki the upper Lowitz arc was continuously in the sky for over three hours. In addition to Lowitz, there were also pyramidal crystal halos (9 halo/column arc?, 24 lower plate arcs, 18 plate arcs), helic arc and Wegener anthelic arc.

The photograph above is taken by Jukka Ruoskanen, and more photographs can be found here. In Helsinki the display was photographed by Marko Riikonen, in Espoo by Panu Lahtinen and Timo Kuhmonen and in Turku by Ismo Luukkonen

By Jukka Ruoskanen

First odd radius halos observed 31st January 2007

While at work on break I saw some cirrus clouds gather in the sky and I later saw a halo appear so I got my camera out of the car and my sunglasses. As the minutes passed I notice that there were three halos: 9 degree halo 18 degree halo and possible 23 degree halo. The left side of the 9 degree halo looks strange because it is brighter on one side and has a somewhat vertical look to it.

When I later downloaded the pictures I went through them with adobe photoshop and I applied the USM and I noticed possible 20 degree halo and even a 35 degree halo! You can see at least 4 halos in the enhanced photo. The possible 9 degree column arc and 35 degree halo have been pointed out with black arrows.

9° column arcs in Prague

Today Ondrej Vlach seen nice Lunar display in Prague, Czech. Halo, upper tangent arc and rare 9 column arcs. Ondrej say: "Left side of 9 halo was very bright and I was took some photos at 22:40 UT. I use Registax for photo stacking."

Circumscribed halo and pyramid halos in Sardinia

This display was captured by Jan Drahokoupil in Sardinia on 6. September. The 22° halo is surrounded by elliptical circumscribed halo. The small halo around the sun is 9° halo or 9° column arc (or both together). Simulations could give better clue. Later on the display changed and there were also 18° plate arcs.

More photos here.

Odd radius halos and diffuse arcs in Fairbanks

Alaskan town Fairbanks is renowned for it's odd radius halos during the winter. On 10. March 2006 there was odd radius halos but also diffuse anthelic arcs - a treat much less commonly seen in Fairbanks. According to Walt Tape the display lasted for several hours and was different in different parts of town. Outside the town no halos were visible, which indicates anthropogenic origin of the display.

In addition to diffuse arcs, another curiosity was also seen: odd radius column arcs. While they are regularly observed in high clouds, in diamond dust they have occurred only once before, at South Pole. The photo above, taken by Tape, shows poorly developed 9° odd radius column arcs as enhancements on the sides of the 9° halo.