Tuesday, 18 September 2018

28° plate arc captured in Haikou, China

On the evening of Sep 5, 2018, an odd-radius plate display of great significance was captured in Haikou, China, by photographer Zhan Guorong. The photos, when enhanced, reveal an elusive coloured arc between 24° and 35° plate arcs, which doesn't fit into any ordinary odd-radius halo families.

© Zhan Guorong, shown with permission
The arc was later confirmed by Dr. Nicolas Lefaudeux to be the exceedingly rare 28° plate arcs, which previously had only two known records world-wide. They were first observed in the 1997 Lascar display in Chile (http://www.thehalovault.org/2008/12/lascar-display.html), and spotted for the second time in Chengdu, China by photographer Jin Hui on July 20, 2016. We've got permission from Jin Hui to share his great capture to the world.

© Jin Hui, shown with permission

Unlike the Lascar display which lasted for almost a full day with many new arcs/halos discovered, displays in Chengdu and Haikou were short-lived with no other new arcs/halos apart from the 28° plate arcs. The lack of associated arcs and restricted solar elevation make it difficult to fully understand what really happened up in the clouds. Isolated 28° plate arcs can be reproduced in simulations by either triangular pyramidal crystals with 30-32 pyramidal faces [1] or octahedral cubic ice crystals with an octahedral face horizontal [2]. Both models require rather restricted shape/orientation conditions.

photo enhancements by Nicolas Lefaudeux, simulations with home-made program by Zhang Jiajie

Dr. Lefaudeux brought up another interesting point. The 9° and 24° plate arcs were totally missing in Lascar, implicating the absence of middle column sections in the pyramidal crystals. In Haikou and Chengdu though, they were present and quite strong.

Are these displays simply variants of the Lascar display with different crystal combinations? Or are we looking at a totally new breed? We'll need more photos at different solar elevations to unravel the mystery. Good news is that now we know such displays can probably occur anywhere. Before the Haikou case, we thought that the responsible crystal clouds are high mountain related since Lascar and Chengdu sit beside the Andes and the Himalayas respectively. The clouds responsible for what happened in Haikou, however, had their origin in the middle of South China sea.

We encourage skywatchers world-wide to keep an eye out for these elusive arcs. They might just pop up in the next odd-radius display over your backyard.

Jia Hao

[1] Nicolas A. Lefaudeux, "Crystals of hexagonal ice with (2 0 -2 3) Miller index faces explain exotic arcs in the Lascar halo display," Appl. Opt. 50, F121-F128 (2011)

[2] M. Riikonen, M. Sillanpää, L. Virta, D. Sullivan, J. Moilanen, and I. Luukkonen, “Halo observations provide evidence of airborne cubic ice in the Earth’s atmosphere,” Appl. Opt. 39, 6080–6085 (2000)

Thursday, 31 May 2018

Odd radii halos outbreak in the Czech Republic

There was an odd radii halos outbreak in the Czech Republic and Hungary in the past few days.
Multiple rare halo forms were captured.
Let me show you some of the photos:

These were taken by Jiří Kaňovský from Černotín, Czech Republic:

He managed to capture 9° contact arcs, 9° parhelion and 24° parhelion among others. Uppercave Parry was captured, too.

These were taken by me:

I am very confused about the halo forms captured here. First I thought I captured 18° parhelions, but now it turns out those are probabaly 20° and also 35° column arcs. There is also a faint lower 23° parhelion. 9° contact arcs are possibly captured, too.
The sun was 62° high at the point of the photoshoot.
I managed to stack multiple photos and edit those in Photoshop to bring out the halo forms.
Can anyone confirm that those are indeed column arcs?

Here are some .NEFs (Nikon's RAWs) if you're interested:

Saturday, 14 April 2018

Odd Radius Display, Bolton, United Kingdom

On the 5th April 2018, there was a short lived but rather nice odd radius display in Bolton, a town situated in the north west of the United Kingdom. As I was preparing to go to work, I noticed the top of what I initially took to be a 22d halo. However, it rapidly developed and became more complex and very soon an 18d became easily visible to the eye. The display lasted about thirty minutes in total and I was only able to take a few single shots and a couple of stacks before it began to fade and I had to leave. Upon processing the images, 9, 18, 23, 24 and 35d halos with attendant plate arcs were identified as being present.

Processing courtesy Nicolas Lefaudeux.

Thursday, 5 April 2018

Pyramidal Crystals Attacked Hungary

Photo by: Károly Tuszinger - Budapest, Hungary (single frame)
Despite the government’s efforts to stop “invaders” at the border, a lot of pyramidal ice crystals could penetrate our homeland on the 3rd of April. At least 3 legions of them rushed across the country arriving from West and reaching the Eastern borders late in the afternoon. The attack had left a lot of people with severely high adrenaline levels – and a lot of excellent photographs! 
Photo by: László Dombai - Vép, Hungary (single frame)
The first signs of the display appeared at early dawn when a vivid circumscribed lunar halo formed with some moondogs, faint CZA and easily visible, still faint supralateral arc. In some pics an extremely faint 9d halo was noticed later (I could not see it while being outside). Then after sunrise in the early morning, parts of 18d arcs were visible, probably they were 18d parhelia, but this only lasted a very few minutes and they were also faint. For some hours nothing happened, then at noon another pyramidal crystal containing cirrus arrived and caused a fine display at my place which lasted for about 20 minutes. 9-18d halos were well visible and also the „22d” halo’s arc was too broad to be a simple 22d halo. I took some pics around, but 35d was not present. In the meanwhile the clouds drifted towards East, they were on their way to Budapest and the surrounding area where a lot of people could observe and capture the best of the show in the afternoon. This region had received the elite commando of the pyramidal legions, with an extremely vivid display; the arcs were easily seen even on the worst quality weather webcams’ images! Webcam videos of idokep.hu: Fót and Hajdúszoboszló, Hungary. 

A decent full circle 9d halo with colourful 9d parhelia appeared on most pics, the full circle 18d halo with vivid 18d parhelia was also present, 23d full circles with some cases of 23d upper parhelion (or at least the arc’s colour was much more vivid at the location of the 23d upper parhelion). One wide angle pic shows signs of a very faint 35d arc too. The show lasted about an hour (at least the N parts of the capital). Then the clouds drifted on towards the East and caused a less spectacular but still fine display late afternoon. The northern half of the country was affected by the display or at least parts of it during the day. 

35d halo on the single frame image of Péter Lenkei from Ötschergraben, Austria
Of course this is the case when stacking would lure out more detail, but most people just rushed out from their workplaces to capture the rarity with their cellphone cameras, still the beauty of the show was that even without stacking many details were visible.

I guess it was very lucky that the clouds had done their best in the Budapest area where most of the population concentrates, so many observers could capture the show. I can’t remember any similar case of pyramidal display in Hungary in the past 20 years, it was so vivid, so widespread and so complex!

By: Mónika Landy-Gyebnár

Sunday, 1 April 2018

In Memoriam Tibor Ádám Tátrai

Tibor's photo taken on 14 April 2015.
Tibor Tátrai, one of the most prominent and active figures of the Hungarian halo scene died at the age of 22 this week. He had been watching the sky since his teenage years, and made many excellent observations. He was our diamond dust king who had more diamond dust observations in his short life than most of the senior members.
Tibor's observation two weeks ago
His last post in our forum this Tuesday was about a dream he had on halos: "I was dreaming about diamond dust and a 22 degree lunar halo with paraselenae on both sides. (...) In the morning the diamond dust fall continued, and in the sunshine the lower tangent arc became visible. In the afternoon there were showers and May weather, and in the clear Western sky a rainbow appeared, while the sky was cloudy above me. The rain was falling, and I was walking in the garden. In my dream I was thinking about how the afternoon Sun could be in the Eastern sky, and how there could be a rainbow if clouds were covering the Sun (...). Yet, I continued photographing happily."

Last summer he received an award from his village for his photos which became the part of the village's "treasure trove".

We'll miss him.

Monday, 5 March 2018

Odd radius plate display from the Czech Republic

On 4th March Jitka R. from the Czech republic captured this magnificent odd radius display on the Moon. After stacking multiple images, many halo forms showed up - particulary 9°, 18°, 20°, 24° and 35° halos, along with 9° and 24° plate arcs.

It was a case of sublimating cirrus, which could be easily seen on the satellite images.

And I have a question for the halo experts - is it possible that the 9° column arcs are captured, too? Or could it just be a cirrus of a higher quality?

Monday, 19 February 2018

Halo Complex 2-18-18

Seems like the rare halos keep coming. While visiting my brother and his family I was outside his house watching this halo complex evolve. In terms of rare halos I got parry, 120d parhelia, Wegener arcs, blue on parhelic circle. While enhancing pics and I saw it in pics afterwards an inverted V shaped arc outside the parhelic circle. Could this be hi-sun Tricker arc?

Marko Riikonen what do you think?

Saturday, 17 February 2018

Cult of the Natural?

Occasionally, I get the impression, rightly or wrongly, that some observers consider halos which have been produced by spotlights to be in some way ‘inferior’ or ‘artificial’ when compared to those which have been produced either by the sun or moon. This position is never explicitly stated but is, rather, vaguely hinted at as if there is some unspoken ‘cult of the natural’ operating in the background. The purpose of this post, therefore, is to pose a few questions to our readers and to solicit their thoughts and opinions on the matter. 

For example, do you think that ‘natural’ halos produced by the sun or moon are in any way better than those produced by a lamp? In this context, what do we mean by ‘natural’ and ‘better’? Likewise, are we to consider halos produced by a lamp to be in some way 'inauthentic' or unworthy of our attention? If that is the case, on what do we base our conclusion? Then again, is there really an inherent dichotomy between ‘natural’ and ‘artificial’ in this regard or is the light source completely irrelevant? Finally, are lamp generated halos merely tolerated or deemed acceptable only in the absence of a solar or lunar equivalent?

My own position is that I don't really have a problem with spotlight displays. Whilst I am always pleased to see a good quality solar or lunar display, I consider halos produced by spotlights to be equally valid and at times arguably necessary in the pursuit of the highest level of halo research. Indeed, I would suggest that lamp work has the additional advantage of repeatability (given the presence of the right crystals) and also that an observer can adjust the elevation of the lamp to produce specific effects; such flexibility would simply not be afforded to those who opt for a ‘natural’ only light source approach. Historically, many halos would not have been discovered if it were not for the adoption of this technique, rather they would have remained theoretical possibilities. In this way, I think it is reasonable to suggest that lamp generated halos have demonstrably accelerated halo research.

In closing, I offer above and below two images for your consideration. They were both taken by Marko Riikonen, the world's foremost exponent of the spotlight technique. The display was photographed on 5th/6th November 2008 in Rovaniemi, Finland, one set taken during the night using a lamp, the other set taken the following day. Both images were photographed in roughly the same location and the swarm responsible for the display had remained fairly stable during the intervening period to facilitate this comparison. The images are virtually identical, the only difference being the light source in each case. Are we to conclude then that the daytime images are superior to those taken several hours earlier during the night? Is there really a qualitative difference between the two or is the 'cult of the natural' just a psychological construct? Your comments and opinions as always are greatly appreciated.
© Both images Marko Riikonen

Saturday, 10 February 2018

Elliptical Halo, Lapinjärvi, Finland 23rd January 2018

Following hard on the heels of Michael Ellestad's recent elliptical halo sighting, we have this little gem observed by Mirko Lahtinen in Lapinjärvi, Finland on the 23rd January 2018. Mirko says the halo appeared at about 11.31am in a kind of low level haze and lasted for about ten minutes in total. Ambient temperature at the time about -15°C and images taken on a Motorola MotoG3.

All images copyright Mirko Lahtinen.

Saturday, 3 February 2018

Project Kern Update

Just under a year ago, we launched Project Kern, the aim of the project being to “try to photograph as many Kern arcs as possible [in a twelve month period]…. to better understand their frequency and to ascertain whether they really are the rarest of the rare”. I am very pleased to announce that almost at the end of the allotted twelve month period of the project we have received our first Kern.
On 20th January 2018, Pasi Vormisto observed an excellent halo display whilst driving just outside the town of Nokia close to the city of Tampere in Finland. Upon finding a suitable parking spot, he managed to document the whole of the display and in so doing photographed several rare halo forms including Tape arcs and 44° parhelia. However, of great interest to us is the Kern arc which appeared in a couple of the frames. One of the characteristics of this particular example is how bright it appears to be. It is readily visible without any additional processing and one wonders whether it would have been visible to the naked eye or in a mirror. One might also speculate as to what kind of monster this would have become if a sequence of images had been taken on a tripod for later stacking. However, every credit must been given to Pasi for even remembering to photograph the area around the circumzenithal arc. All too often, observers become transfixed by all the ‘action’ occurring in the immediate vicinity of the sun.

So then, can we draw any tentative conclusions? I think the jury is still out, but on recent evidence it seems as though they are appearing once or twice per year. For example, in 2015, we had Eresmaa’s two UK Kerns and in 2016 we had Riikonen’s daylight Rovaniemi Kern. Of course, we don’t know how many actual Kerns there were that went unobserved/un-photographed. Although Project Kern is now drawing to a close, there is still time to add to our grand total of one. If it has taught us anything, it is the need to encourage as many observers as possible to routinely photograph the area around the zenith and better still to stack their images. In this way we may better understand their frequency and distribution.

All images copyright Pasi Vormisto.

Monday, 29 January 2018

Surface Halo Arcs on Icy Puddle

Surface halos were observed on frozen puddles by Hungarian observer Dávid Hérincs. He photographed the halos on the morning of 25 January at about 10° Sun elevation. As he reported, with naked eyes he could only see the glittering of ice, the halos came out only afterwards in the photographs. Besides the subsun and subparhelia, sharp halo arcs were also photographed which look like lower tangent or Parry arcs. Can anyone provide some explanation for what exactly these are? More images.

Photo of a similar phenomenon by Dávid Hérincs from 30 December 2016.