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.

Friday, 26 January 2018

Elliptical Halo January 25th 2018

Following my recent observation of subparhelia and sub-PHC on the car windshield earlier in the week, yesterday I had another great catch. Whenever I see altocumulus clouds the first thing that comes to mind are elliptical halos. A large patch of blue sky appeared and looking up, sure enough there was an elliptical halo! I brought the camera and I took a bunch of shots of the halo some of which I present here. I have a feeling the 2018 halo and sky optics season is going to be a good one.

Thursday, 25 January 2018

Testing the spotlight

This year's winter in the Czech Republic is very mild. Only three situations occured with enough moisture and deep enough temperatures for halos to form. January will be most probably somewhere around 3°C above normal. NAO (North Atlantic Oscillation) is most likely responsible - with it being well in the positive values, constant flow of low pressure systems from the west hinders any chance for very cold continental air to move in from the east. While this mode brings fairly moist oceanic air, temperatures oscillate around zero degrees Celsius, which does not correlate with halos.

On December 29th, 2017 it was different. Rather cold and moist air settled in the Czech Republic, influenced by a low centered in Scandinavia and high pressure ridge from the SW. As the temperatures were dropping well below zero degrees Celsius, I decided to keep an eye on the cameras in case something was happening.

And it sure was. A few hours after the sunset, they started the snow guns at Kyčerka ski centre. Only a few moments later, bright and glistening upper tangent arc could be seen extending from a strong lamp situated at the ground level of the ski slope.

I decided not to waste any time and quickly packed my gear along with a new spotlight and headed for the ski centre. I "packed" a friend with me, too.

An interesting addition - the route for the ski centre begins rather tediously, leaving the town of Ostrava and heading for the glorious mountain ridges and crests of the Beskydy mountains. As you're approaching, beautiful scenery opens up. The brighter the Moon and the larger the snow cover the better.

This is a picture of one of the many ridges, lit by an almost full Moon. It was taken at a different time, while also heading for halo hunt.

To arrive at Kyčerka, you have to drive over some of these ridges. And as we were at the highest point of our journey, we eventually drove through cloud cover. Only waiting for some nucleating agent, as the temperatures were somewhere around -6°C.

We were only 2 kilometers away from our destination and at Jezerné (a much smaller ski slope in Velké Karlovice) the halos already started.

At our destination Kyčerka, the snow guns were on full blast. And even though the cloud cover we drove through previously only hovered above the highest peaks, well far away from Kyčerka, soon the crystals developed and began to swallow the whole valley of Velké Karlovice in a thick ice fog. For the first time ever I've experienced the marvelous glints in a bright spotlight.

Unfortunately though, the temperature didn't drop much below -10°C, so plates were almost non existant. There were glints where parhelions are supposed to be, and in the photos some brightening at the left and right sides of the 22° halo are visible, but it wasn't enough to produce major light pillars, CZAs or others.

I am a little bit scared that there may be only one situation ahead - the temperatures are forecasted to drop at the end of January, but I don't think it will be any different. So it doesn't seem like I will be the first one in the Czech Republic to hunt the Kern arc. Or at least.. not yet!