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

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.