halo search engine

Google has created a new service, "Custom Search Engine". I used this service to create a "Halo search" - search on all good sites dedicated to halo phenomena. This service can be used on any webpage (simple script), or on the home search page.

For example, when I try to search Minnaert's cigar in Halo Seach - I get 3 links, then try to search in a google "Minnaert's cigar" - 4 link, then in google, but Minnaert's cigar (without "") - 341.

You are welcome to use and improve it.

Crystal Swarm Effects

Divergent light halos can exhibit peculiar effects that are attributable to a homogenous or nonhomogenous crystal swarm. Here we present two such effects, where different parts of the "Minnaert cigar" are present in halos.

Image 1 displays a strong upper tangent arc (the whole frame and a crop is provided). It consists of two distinct parts: the upper part formed in bright separate glints and the lower more diffuse part. The diffuse part of the arc is formed in crystals further away from the camera, narrowing along the Minnaert cigar towards the lamp. The upper part is formed in crystals closer to the camera.

It is perhaps worth pointing out that the Moilanen arc is visible only in separate glints. This suggests that in this display it only formed in crystals closer to the camera, hit by relatively non-divergent rays.

The crystal swarm was homogenous as it had already travelled few kilometres from the snow guns. Total exposure time for the image 1 is 630 seconds.

Image 2 presents two photos of different stages of a display. During stage 1 the halos look familiar: 22° halo, upper tangent arc and Parry arc among others are present. During stage 2, however, some curious changes have occurred. It looks like the tangent arc has shifted towards the lamp. Also, less clearly, there is a section of an additional circular halo on the left, apparently having the same radius as the shifted tangent arc.

The effects observed during stage 2 must be caused by inhomogeneity of the crystal cloud between the observer and the lamp (the snow guns were right next to the point of observation). The crystal swarm was more concentrated close to the lamp causing the shift of the tangent arc and 22° halo along the Minnaert cigar. This is supported also by the weakening of these halos at their normal radii, formed in close by separate crystals (compare to stage 1). An animated gif is provided for an easy comparison.

These shifted halos represent a vertical cross section of the Minnaert cigar close to the lamp. Horizontal cross section of 22° halo has been documented on snow surface, as shown by these photographs: surface halo 1, surface halo 2.

Marko Riikonen & Jari Luomanen

Diamond dust shocks in Hyvinkää, Finland

On the evening of 13th December the temperature was dropping fast and moisture level was above 95%. It was time to go. And what an evening it turned out to be! Very good crystal material created amazing halos in the beam of a portable light or car headlight. A crystal swarm lasted typically less than 15-30 minutes at a given location and then the search for another good spot started. Later in the night I was able to enjoy a display for maybe an hour at a completely dark field. During that time I had time to lay on my back (while the camera exposure was ongoing) and absorb the amazing sight.

There are several interesting features in the photos (blue spot, the "dark loop" on top of diffuse arcs etc.). On the attached photo there is a rough draft simulation illustrating the different intensity effects. Obviously fine tuning has to be done. More photos and some text can be found here. A more detailed description will follow after I have had time to concentrate on the photos and simulations.

Home Made Halo

During the past year and a half I have tried to figure out how to build a Snowgun. Or, rather, an ice crystal gun since snow is not needed for creating halos. Hence, the objective has been to construct a "halo gun".

After some unsuccesful experimenting I came up with an idea of mixing small amounts of kaoline with water and spraying the solution into air. Kaoline is low cost material mainly used in ceramic industry. The halo gun itself is a simple device: all is needed is an air compressor and a paint spray gun.

On 28 November the weather finally allowed for testing the device. When sprayed into air the solution immediately transformed into ice crystals. I followed the crystal swarm to a nearby road to see whether it created any halos. It certainly did. After the second spraying the halos got even better. I observed both 22 and 46 degree halo, CZA, UTA, M-arc, parhelia, and parhelic circle. The above photograph was captured during the peak of one halo gun generated display.

The halo gun even worked with hot water which prevented the nozzle from freezing. Without Kaoline I was not able to produce ice crystals, regardless of the temperature of the water. Clearly, kaoline plays a huge part in the nucleation process.

Thus far the highest temperature where I have successfully created haloes using this method has been as high as -2 degrees celsius. This ice nucleation temperature is significantly higher than what is cited for Kaolin in various sources in literature. Similar high-temperature ice nucleation characteristic is known for Pseudomonas syringae bacterial protein, which is commonly used to intensify snow production in snow guns.

In January we will go with a small group of people to Kilpisjarvi biological station in the northhernmost Finland to experiment more thoroughly with halo making.

Divergent light effect around power cables

This divergent light effect was observed around power cables that reflected light from a bright lamp. The lamp was positioned behind and above the cables. The bulb of the floodlight can be seen through the dark filter.

The photographs were shot between 1 and 2 am, 29 November 2007 in Tampere, Finland. At the time of the observation the ambient temperature was -4 - -3 degrees Celsius.

The cables’ surface appears to reflect light very well. The effect was visible from a rather narrow sector only. As the observer moved sideways, the effect disappeared. At the peak of its intensity, when the telephoto shot was taken, it was very bright. The effect was clearly defined as is shown in the photographs.

Divergent light parhelia as well as upper and lower tangent arcs were also observed. The divergent light upper tangent arc can be distinguished as the diffuse glow above the lamp. In the telephoto shot it manifests itself in the individual crystal trails between the camera and the cables. In this sense, the image shows two halos on top of each other. Strong pillars and UTAs were observed above light sources further away (see image 2).

The effect around the cables had a 3D appearance, like a vortex or a funnel, but it did not extend towards the observer. Rather, it seemed to encapsule the cable. The other halos that formed in the light of this lamp had a strong 3D character. Both tangent arcs as well as the parhelia arched along the Minnaert’s cigar from the eye of the observer towards the lamp. Unfortunately, this 3D effect cannot be satisfactorily captured in a still photograph.

Earlier that night it had proved difficult to photograph crystal samples due to high temperature. Towards the end of the display the temperature had risen to -3 degrees Celsius. Hence, no crystals were photographed during the observation. However, the known halos observed suggest that singly oriented columns and plates were prominent in the crystal population.

At the time of the writing (10 December 2007), the cause of the effect remains unknown. Hypothesises concerning the nature of the effect are most welcome as are previous observations in case there are any.

For larger images, see here.

New home for Halo Reports

Because users are increasingly unhappy about the terms of use for the Blogger, we have decided to move the Halo Reports to another server. The new home is at the Ursa Astronomical Association server. Veikko Mäkelä made all the ground work. No more postings can be done to Halo Reports here, at the Blogger. With time, we try to move the old postings to new home so that the Halo Reports here at Blogger could be permanently removed.

The panorama is from Rovaniemi in the end of November.

Sky Haloes in Southern Germany

this year only few haloes appeared over Germany, I could observe the second complex halo display on Mt. Wendelstein. In the morning I saw my first subsun in this year, which appeared in freezing fog. Later a veil of cirrostratus from a low pressure area over the Mediterranean Sea crossed the Alps from the south. Under those weather conditions, large halo displays can be seen very often. In my own statistics, 80% of all larger halo displays appeared when there was a southerly stream of air over the Alps, or under foehn conditions. And also this time there was a large choice of haloes in the southern part of the sky, which lasted for about two hours and a half. Between 10.10 and 12.45 CET the 22°-halo, a bright upper tangent arc and a faint Parry arc, both sundogs with Lowitz arcs, the parhelic circle, an almost complete supralateral arc, a faint infralateral arc on the right side, and a complete sun pillar were visible. Unfortunately, the haloes appeared only over a small area on the northern rim of the Alps. So except of me, only my husband who was down in the valley at that time, could enjoy similar haloes.

Text: Claudia Hinz

Sky Haloes in Southern Germany

Although this year only few haloes appeared over Germany, I could observe the second complex halo display on Mt. Wendelstein. In the morning I saw my first subsun in this year, which appeared in freezing fog. Later a veil of cirrostratus from a low pressure area over the Mediterranean Sea crossed the Alps from the south. Under those weather conditions, large halo displays can be seen very often. In my own statistics, 80% of all larger halo displays appeared when there was a southerly stream of air over the Alps, or under foehn conditions. And also this time there was a large choice of haloes in the southern part of the sky, which lasted for about two hours and a half. Between 10.10 and 12.45 CET the 22°-halo, a bright upper tangent arc and a faint Parry arc, both sundogs with Lowitz arcs, the parhelic circle, an almost complete supralateral arc, a faint infralateral arc on the right side, and a complete sun pillar were visible. Unfortunately, the haloes appeared only over a small area on the northern rim of the Alps. So except of me, only my husband who was down in the valley at that time, could enjoy similar haloes.

More photos from three weeks ago in Rovaniemi

It seems putting the photos of the recent displays to my web page will delay. So, in a meanwhile here are two more photos of the display three weeks back.

When light source is at 0° elevation, some difficulties arises in identifying certain halos. Tricker arc and subanthelic arc merge together, as do helic and subhelic arcs. However, the subanthelic arc is formed by Parry-oriented crystals, while Tricker arc is from singly oriented columns. Because in this display the 46° supralateral arc is rather strong, and there are only weak indications of 46° Parry or Tape arcs, probably singly oriented columns were in command. The even brightness of the Tricker/subanthelic loop is also typical for Tricker arc. Subanthelic arc has strong brightenings on the sides - at least in the simulations - and that is actually what seems to be present in the the display of last weekend.

The reason why halos are seen so strongly in the halogen light is probably the relatively dark background sky as compared to sun or moon situation. Yet all the halogen lamp displays that I have photographed so far have been hampered by city lights. Once the crystal cloud drifts to the dark outskirts of the city, more intense appearances should be expected.

More photos from three weeks ago in Rovaniemi

It seems putting the photos of the recent displays to my web page will delay. So, in a meanwhile here are two more photos of the display three weeks back.

When light source is at 0° elevation, some difficulties arises in identifying certain halos. Tricker arc and subanthelic arc merge together, as do helic and subhelic arcs. However, the subanthelic arc is formed by Parry-oriented crystals, while Tricker arc is from singly oriented columns. Because in this display the 46° supralateral arc is rather strong, and there are only weak indications of 46° Parry or Tape arcs, probably singly oriented columns were in command. The even brightness of the Tricker/subanthelic loop is also typical for Tricker arc. Subanthelic arc has strong brightenings on the sides - at least in the simulations - and that is actually what seems to be present in the the display of last weekend.

The reason why halos are seen so strongly in the halogen light is probably the relatively dark background sky as compared to sun or moon situation. Yet all the halogen lamp displays that I have photographed so far have been hampered by city lights. Once the crystal cloud drifts to the dark outskirts of the city, more intense appearances should be expected.

More results from the latest display in Rovaniemi

Here is some more material from the diamond dust in Rovaniemi three nights ago. After the heaviest Parry-crystal bombarding was over, Moilanen arc appeared, as shown in the photo on the left. Moon gives the beauty spot.

I have crystal photos from this stage, but as usual, they give no clue to Moilanen arc. In the earlier Parry-stage there was no indication of Moilanen arc whatsoever, but I did not manage to get the crystals. This bugs, because comparing the samples might have pushed us forward in solving the mystery.

The upper left image shows parhelia from streetlamp - the stripes that are parallel to the electric lines. Then there are also arcs extending slightly obliquely downwards. While visually parhelia curved towards me, these other arcs curved away and around me. As far as I understand from looking at divergent light simulations by Lars Gislen et. al, this effect is a 120° parhelion. In the photo only the brightest part of 120° parhelia is seen, visually the crystal glitter extented much further. Also a full parhelic circle was seen visually.

The lower left photo shows what was seen around the half moon at its best. For long time there was hardly no moon halo, although in the beam of the halogen torch a great display was present. Some indication of Lowitz arcs is present in the moon photo. The crystal sample may be representative of this stage, but I am not sure.

More results from the latest display in Rovaniemi

Here is some more material from the diamond dust in Rovaniemi three nights ago. After the heaviest Parry-crystal bombarding was over, Moilanen arc appeared, as shown in the photo on the left. Moon gives the beauty spot.

I have crystal photos from this stage, but as usual, they give no clue to Moilanen arc. In the earlier Parry-stage there was no indication of Moilanen arc whatsoever, but I did not manage to get the crystals. This bugs, because comparing the samples might have pushed us forward in solving the mystery.

The upper left image shows parhelia from streetlamp - the stripes that are parallel to the electric lines. Then there are also arcs extending slightly obliquely downwards. While visually parhelia curved towards me, these other arcs curved away and around me. As far as I understand from looking at divergent light simulations by Lars Gislen et. al, this effect is a 120° parhelion. In the photo only the brightest part of 120° parhelia is seen, visually the crystal glitter extented much further. Also a full parhelic circle was seen visually.

The lower left photo shows what was seen around the half moon at its best. For long time there was hardly no moon halo, although in the beam of the halogen torch a great display was present. Some indication of Lowitz arcs is present in the moon photo. The crystal sample may be representative of this stage, but I am not sure.

Another halogen lamp display from Rovaniemi

A bright halogen spotlight and diamond dust is a magic combination. Spot yourself exactly in the middle of the beam and breathtaking halo views may rewards you. An outsider will see just somebody bathing in the light and may wonder what is going on. There might be a Moon in the sky at the same time - like in the case shown here - but it shows hardly no halos at all. The lamp creates its own universe of halos.

The Ounasvaara snow guns created this display last night in Rovaniemi in the beam of a Cyclops Thor Platinum X-15 halogen lamp. Because of the lack of 46° lateral arcs, this display must have been dominated by Parry crystals. Indeed, in the lower right image there are both upper and lower Tape arcs as an indication of Parry orientation.

An interesting feature is seen in the images on left (the lower image is an unsharp masked from the upper). There seems to be a loop inside the helic arc. Much like the loop formed by the subanthelic arc.

On the upper right is a simulation that shows a quite similar loop (arrow). The crystals in simulation are Parry oriented and they are semitriangular, a half way between a triangle and regular hexagon. The thing in the photo looks to me like a halo and it might be the one shown in the simulation. I have not raytraced it, so I don't know what it might be called. There are some differences in the loop sizes between the simulation and the photos, but then again the projections are not exatly the same.

A bit more could be said about the results of the last night, but this must do for now. The simulation was made with a program by Jukka Ruoskanen.

Another halogen lamp display from Rovaniemi

A bright halogen spotlight and diamond dust is a magic combination.

Spot yourself exactly in the middle of the beam and breathtaking halo views may rewards you. An outsider will see just somebody bathing in the light and may wonder what is going on. There might be a Moon in the sky at the same time - like in the case shown here - but it shows hardly no halos at all. The lamp creates its own universe of halos.

The Ounasvaara snow guns created this display last night in Rovaniemi in the beam of a Cyclops Thor Platinum X-15 halogen lamp. Because of the lack of 46° lateral arcs, this display must have been dominated by Parry crystals. Indeed, in the lower right image there are both upper and lower Tape arcs as an indication of Parry orientation.

An interesting feature is seen in the images on left (the lower image is an unsharp masked from the upper). There seems to be a loop inside the helic arc. Much like the loop formed by the subanthelic arc.

On the upper right is a simulation that shows a quite similar loop (arrow). The crystals in simulation are Parry oriented and they are semitriangular, a half way between a triangle and regular hexagon. The thing in the photo looks to me like a halo and it might be the one shown in the simulation. I have not raytraced it, so I don't know what it might be called. There are some differences in the loop sizes between the simulation and the photos, but then again the projections are not exatly the same.

A bit more could be said about the results of the last night, but this must do for now. The simulation was made with a program by Jukka Ruoskanen.

More results from the latest display in Rovaniemi

Here is some more material from the diamond dust in Rovaniemi three nights ago. After the heaviest Parry-crystal bombarding was over, Moilanen arc appeared, as shown in the photo on the left. Moon is giving the beauty spot.

I have crystal photos from this stage, but as usual, they give no glue to Moilanen arc. In the earlier Parry-stage there was no indication of Moilanen arc whatsoever, but I did not manage to get the crystals. This bugs, because comparing the samples might have pushed us forward in solving the mystery.

The upper left image shows parhelia from the streetlamp - the stripes that are parallel to the electric lines. Then there are also arcs extending slightly obliquely downwards. While visually parhelia curved towards me, these other arcs curved away and around me. As far as I understand from looking at divergent light simulations by Lars Gislen et. al, this effect is a 120° parhelion. In the photo only the brightest part of 120° parhelia is seen, visually the crystal glitter extented much longer. Also a full parhelic circle was seen visually.

The lower left photo shows is what was seen around the half moon at its best. For long time there was hardly no moon halo, although in the beam of the halogen torch a great display was present. Some indication of Lowitz arcs is present in the moon photo. The crystal sample may be representative of this stage, but I am not sure. Crystal photos of Lowitz displays are also very welcome.

Moilanen arc in Rovaniemi

Yesterday it was halos from sunrise to sunset in Rovaniemi. I was biking in the outskirts of the town in hope of getting into the heat of the things, but as afterwards many people told about good halos in and near the center, I think I missed the best action.

Anyway, here is a photo showing Moilanen arc towards the end of the display. The image is stacked from 14 frames taken during one minute. The ice cloud was elevated, only sparse crystals were glittering on the ground. Halos were generated by the snow guns of Ounasvaara ski center. Machines will be running continuously for the next three weeks as soon as it is at least -5°C, so more displays may appear.

Next night pillars were present, but the crystals were not that good.

Text: Marko Riikonen

Moilanen arc in Rovaniemi

Yesterday it was halos from sunrise to sunset in Rovaniemi. I was biking in the outskirts of the town in hope of getting into the heat of the things, but as afterwards many people told about good halos in and near the centre, I think I missed the best action.

Anyway, here is a photo showing Moilanen arc towards the end of the display. The image is stacked from 14 frames taken during one minute. The ice cloud was elevated, only sparse crystals were glittering on the ground. Halos were generated by the snow guns of Ounasvaara ski center. Machines will be running continuously for the next three weeks as soon as it is at least -5°C, so more displays may appear.

Next night pillars were present, but the crystals were not that good.

More diamond dust in Rovaniemi

Last night diamond dust formed again in Rovaniemi with help of Ounasvaara ski resort snow guns. Two photos of what was seen in the light beam of a bright lamp are shown here.

In the upper image are diffuse anthelic arcs. In the lower image a number of common halos are seen together with Moilanen arc. Three white strikes extend from lamp to different directions to the left. Possibly these are parhelic circle (and parhelia), helic arc and superparhelia. Or, some of them may be artefacts formed by the lamp reflector.

Temperature was -6°C and it was overcast sky. The display was limited to the vicinity of the snow guns, these photos were taken at the top of the skiing flank. I was not able to get very far from the lamp, which accounts at least partly for the numerous separate crystals and diffuse looks of the halos. The lamp was on the elevated ground, but I did not make an estimate of the lamp angular elevation.

These are just two randomly chosen photos and may not represent the best output. Much more photos were taken, including crystal photos. I will return to these at some later time.

Text: Marko Riikonen

More diamond dust in Rovaniemi

Last night diamond dust formed again in Rovaniemi with help of Ounasvaara ski resort snow guns. Two photos of what was seen in the light beam of a bright lamp are shown here.

In the upper image are diffuse anthelic arcs. In the lower image a number of common halos are seen together with Moilanen arc. Three white strikes extend from lamp to different directions to the left. Possibly these are parhelic circle (and parhelia), helic arc and superparhelia. Or, some of them may be artefacts formed by the lamp reflector.

Temperature was -6°C and it was overcast sky. The display was limited to the vicinity of the snow guns, these photos were taken at the top of the skiing flank. I was not able to get very far from the lamp, which accounts at least partly for the numerous separate crystals and diffuse looks of the halos. The lamp was on the elevated ground, but I did not make an estimate of the lamp angular elevation.

These are just two randomly chosen photos and may not represent the best output. Much more photos were taken, including crystal photos. I will return to these at some later time.

First diamond dust in Finland

The winter in Lappland was two weeks late but when it finally arrived last weekend, along came the diamond dust. Decent displays were seen here in Rovaniemi on two nights and one day. In the night time I used a bright lamp to create the halos. The photo here is from the second night showing the anthelic region with diffuse arcs. More photos, including all sky views, will follow some time later when I am done with them.

Text: Marko Riikonen

First diamond dust in Finland

The winter in Lapland was two weeks late but when it finally arrived last weekend, along came the diamond dust. Decent displays were seen here in Rovaniemi on two nights and one day. In the night time I used a bright lamp to create the halos. The photo here is from the second night showing the anthelic region with diffuse arcs. More photos, including all sky views, will follow some time later when I am done with them.

Pyramidal crystal halos

A funny coincidence that a halo-observer may want to experience is travelling to Egypt and seeing some pyramidal crystal halos. This odd-radius display was photographed by Márk Laczkó of Budapest, Hungary somewhere over the southern borders of Romania. He was sitting on an airplane heading towards Egypt on 27th October. When he realised they were flying in cirrus clouds, he deliberately started looking for some halo phenomena. The surprisingly well distinguishable 18°, 20°, 23° and 24° halos were visible for about a minute at 06:21 UTC. Unfortunetally there is no documentation or report of a possible 35° halo. The original photo ( 1 ) and two other pictures are also available ( 2 - 3 ).

Pyramidal crystal halos

A funny coincidence that a halo-observer may want to experience is travelling to Egypt and seeing some pyramidal crystal halos.

This odd-radius display was photographed by Márk Laczkó of Budapest, Hungary somewhere over the southern borders of Romania. He was sitting on an airplane heading towards Egypt on 27th October. When he realised they were flying in cirrus clouds, he deliberately started looking for some halo phenomena. The surprisingly well distinguishable 18°, 20°, 23° and 24° halos were visible for about a minute at 06:21 UTC. Unfortunately, there is no documentation or report of a possible 35° halo. The original photo and two other pictures are also available (#1 and #2).

Elliptical Halo in Vecsés, Hungary

Today on 21st October at 11:27 local time I saw this elliptical halo above Vecsés, Hungary. I was photographing Ac len and iridescent Ac clouds, when I caught sight of the display. The elliptical halo formed on the ice crystal precipitation of one of the Ac. The display lasted less than two minutes, so I really had to hurry to find a good object to shield the Sun with, and not to miss the sight meanwhile. In the first photo - I was still using the neighbouring house's wall, - even the reddish inner side of the halo can be seen. More photos.

Elliptical halo in Vecsés, Hungary

Today on 21st October at 11:27 local time I saw this elliptical halo above Vecsés, Hungary. I was photographing Ac len and iridescent Ac clouds, when I caught sight of the display. The elliptical halo formed on the ice crystal precipitation of one of the Ac. The display lasted less than two minutes, so I really had to hurry to find a good object to shield the Sun with, and not to miss the sight meanwhile. In the first photo - I was still using the neighbouring house's wall, - even the reddish inner side of the halo can be seen. More photos are also available ( 1 )

Austrian halo display with Parry arc

On October 9, 2007, my husband and I made a trip to Austria to visit the highest mountain of that country, Mt. Großglockner, 3798m ( 1 ). The main ridge of the alps gave a warm welcome to us with a bright and diffuse fragment of the infralateral arc ( 2 ). Just a little later, at a sun elevation of 33.4°, a sharply defined Parry arc ( 3 ) formed directly above the upper tangent arc. There were only few occasions that we saw it in such a brightness before. The beautiful halo display was completed by sundogs ( 4 ) and an almost complete parhelic circle ( 5 - 6 ). Even the heliac arc seemed to be present, as we both recognized it. The cirrus clouds, however, showed a very striated structure, so it cannot clearly be identified in our photographs.

In the afternoon, at a sun elevation of 30.9°, a fragment of the parhelic circle appeared in a narrow cirrus fiber together with a bright 120°-sundog. This sundog not only had a greenish and reddish rim ( 7 ), but also showed a striking vertical extension from time to time. Below it there seemed to be kind of cross-formed arcs ( 8 ) like those which normally appear around the anthelion only.

Text: Claudia Hinz

Austrian Halo Display with Parry arc

On October 9, 2007, my husband and I made a trip to Austria to visit the highest mountain of that country, Mt. Großglockner (3798m). The main ridge of the alps gave a warm welcome to us with a bright and diffuse fragment of the infralateral arc. Just a little later, at a sun elevation of 33.4°, a sharply defined Parry arc formed directly above the upper tangent arc. There were only few occasions that we saw it in such a brightness before. The beautiful halo display was completed by sundogs and an almost complete parhelic circle (with unsharp mask). Even the heliac arc seemed to be present, as we both recognized it. The cirrus clouds, however, showed a very striated structure, so it cannot clearly be identified in our photographs.

In the afternoon, at a sun elevation of 30.9°, a fragment of the parhelic circle appeared in a narrow cirrus fiber together with a bright 120°-sundog. This sundog not only had a greenish and reddish rim, but also showed a striking vertical extension from time to time. Below it there seemed to be kind of cross-formed arcs like those which normally appear around the anthelion only.

Halo Complex 15th October 2007

After over 90 days of above 90 degree temps and no halos this half-way decent display shows itsself in high clouds. Upon leaving work, I got quite a few photos. In all I got 22d halo, parhelia, upper tangent arc, bits of parhelic circle, infralateral arcs, 120d parhelia, and an upper suncave parry arc. While on the road I observed a rather bright 120d parhelion on the left side. As the patch of cloud shifted to the north the blue spot appeared and got several photos of it. When enhanced, the bluespot shows green, blue and purple and possible red but can't be sure. The one photo showing the Parry has ugly power lines but could not help that because I was shooting out the car window. If you wondering if I was driving at the time I wasn't because one should not drive and take photos at the same time. During those halo free days the temps were breaking records even in October and it was nice to see halos again.

Complex Halo Display with Wegener´s anthelic arcs in Germany

In the early afternoon of July 8, 2007, Reinhard Nitze could observe the most extensive halo display with 8 different halo types he had ever witnessed.

The most interesting feature of the display was probably the appearing of the anthelion with Wegener´s anthelic arcs attached to it. The left part of Wegener´s anthelic arc was clearly visible to the naked eye, but in the photographs also the right part seems to be faintly visible. One picture, processed by an unsharp mask, even gives the impression of a faint “halo-X” on the parhelic circle. The 120°-sundogs, were clearly visible too.

Also the other side of the sky around the sun looked interesting. The sun was surrounded by a faint 22°-degree halo, and on top of it there was a bright and colourful upper tangent arc respectively circumscribed halo with a Parry arc attached to its upper side. As the circumscribed halo crossed the sundogs exactly, I first thought of the Lowitz Arc (erroneously). Both sundogs were visible, the left one for a short time very bright and colourful. The parhelic circle was faintly visible even inside the 22°-halo on the left side. But this part of it it was not very bright. At its largest extension, two thirds of the parhelic circle were visible. Unfortunately, low clouds often disturbed the observation.

Concave & convex Parry arcs photographed in Georgia

A visitor of my homepage emiled me this photo of a complex display that took place in Rome, Georgia and the year I can't remember but it was in the early 90's and of all the halos the bright upper concave and convex parry arcs are the most interesting. This is probably the best I have seen where both upper parry arcs are visible . Other images show a bright supralateral arc as well. The person who sent the photo is Loren Hall and his email is: bctimebandit@earthlink.com

Blue spot gets more colours

Blue spot is the colour feature of the parhelic circle occurring at the anthelic region of the sky. In addition to the blue, the theory predicts also green, but no red. Yet in several observations also red colour has been reported. However, because the red has never reproduced in photos, the observations have been doubted.

The image here shows two versions of a simulation of plate crystal parhelic circle in the anthelic region of the sky. The upper one has not been processed, the lower one has an overall levels adjustment to enhance colours. It looks like there is red present in addition to blue and green.

So it may be that observations of red may have not been wrong after all and that the theory (and naming) of the blue spot needs to be reconsidered. Lacking of the red in photos may be explained by film and sensor sensitivity issues. Even though the colors are seen with naked eye, they are still weak and some wavelenghts may be more prone than others to be not captured by the photographing equipment.

The simulation was made with a software developed by Jukka Ruoskanen. Sun elevation for the simulation is 25°, the plates have aspect ratio of 0.9 and tilt 3°.

Lowitz Arc in Bochum, Germany

On September 6, 2007, Peter Krämer observed a relatively bright left Lowitz arc in the skies over Bochum in the German Ruhr area. The arc (picture with unsharp mask) stayed visible for about 20 minutes, stretching away upwards and downwards from the left sundog.
Apart from the sundogs and Lowitz arc, there was also a faint 22°-halo visible, together with the upper tangent arc and circumzenital arc.
One hour later, after Lowitz arc and CZA had already faded away, the upper tangent arc became rather bright, and also parts of the supralateral arc showed up.

46° contact arcs

About a year ago in Muonio, Finland, a diamond dust display produced a new halo, the 46° contact arcs. The display was shortly reported in the blog, but no simulation was shown. So here is a simulation, together with a composite of the photos that were taken by Päivi Linnansaari. The 46° contact arcs, which arise from Lowitz-oriented crystals, appear as three arcs below the circumzenith arc.

The Lowitz crystals used in the simulation are regular plate-like hexagons, with aspect ratio of 0.4, tilt about the Lowitz axis 28° and Lowitz axis rotation 1°. Sun elevation is 9°. The Lowitz arcs themselves are faintly visible at 10 and 2 o'clock positions, separating from the 22° halo and reaching towards the upper sunvex Parry arc. This is the circular component of the Lowitz arcs, also known as the c-component (after Greenler).

Occasionally, in high cloud displays there is seen a short patch of 46° halo under the circumzenith arc, as shown here in the photo by Stepanka Kosova, taken on 20 August in Prague. It has been sometimes suspected that these might be indications of 46° contact arcs. Whether that's the case, it may be confirmed if a series of photos are taken for stacking.

The simulation is made with HaloSim by Les Cowley and Michael Schroeder.

Concave and convex Parry arc in Germany

When Stefan Danner was driving home in the evening of September 12th, he saw a pair of very beautiful sundogs. After having reached home, he noticed that there were two more halos – a very rare combination of a concave and a convex Parry arc. He could watch the two arcs getting brighter and brighter by the time. The impressive phenomenon lasted about 10 minutes before it ended showing a bright sundog.

Later, when he looked at the “raw pictures” closely, disenchantment followed: there was not a lot to see for the eyes of a layman. Only after having processed the pictures a little more or less, the effect of the halos in the pictures was like he felt it. (He saw them better than visible in the “raw pictures”, but not as intensive as they look after the processing.)

More pictures

Odd radius display

12th August 2007 - This day I can see interesting halo display. I thought that I could see upper tangent arc and inexpressive 22 degree halo. But the upper tangent arc was more and more brighter and lower tangent arc has not been seen. It crossed my mind that this phenomenon what i can see isn’t 22 degree tangent arc but 23 degree plate arc. I searched another pyramidal halos, but didn’t see it. Through that I took some photo. When I stacked and adjusted this photo was seen 9° halo, 18° halo, 23° upper plate arc and 22° or 23° halo. Lukas Kosarek

More photos: Martin Popek, Nydek (2.7.) , Stepanka Kosova, Prague (20.8.) and Jiri Los, Prague (20.8.)

The Beginning of Halo Season in Hungary

The halo-season in Hungary has began in a very promising way. There were two particularly noteworthy displays this week. 

The first one was observed by László Henez "Felhőcske" on 16th September near Eger, Hungary. As a born halo-observer, even though he was quite unaware of what he was seeing, he took a picture of not only the sunward halos, but the anthelic side, as well, where about a quarter of the bright white parhelic circle was visible together with a Wegener arc curving downwards towards the anthelic point. The 22° halo and the upper tangent arc were seen in the sky covered with uniform Ci for about half an hour after 8:25 UTC, while the anthelic arcs for only a few minutes. László did not see any 120° parhelia or anthelion. More of László’s photos can be seen here.

In the afternoon of 18th September, an odd radius display appeared with pyramidal 18° and 9° halos besides the 22° one. The photo was taken by "Controll" in Jobbágyi, northern Hungary, but the 18° halo was seen in Budapest by Alex Farkas, too. The display started with a 22° halo and lasted for roughly 40 minutes, until 14:15 UTC. "Controll" reported that she had seen a possible 46° halo as well, but it was at the edge of visiblity. It’s worth having a look at the faint pyramidal crystal parhelia in the picture provided. The full-size photo is also available, together with a panorama image of the display.

Composite of the Kajaani display photos

With the diamond dust season soon on our doorsteps, here is a tidbit from last winter. The display was seen in Kajaani on 26 February 2006. It was shortly presented in the blog, but now I made a composite which somewhat better shows the grandeur of the display. On a more technical side, the faintness of the 46 infralateral arc is noteworthy. In simulations this can be obtained with non-regular hexagons. The photos were taken by Kalevi Härkönen, who was at the time walking his dog.

Anthelic arcs in Finland

On August 28th anthelic arcs appeared in the northern part of Finland. My coffee break was suddenly halted as watching from the window I noticed several arcs. Once outside my eye was first caught by well developed parhelic circle. Then, looking up I noticed a colourful Wegener arc. Colours were red on the bottom and blue on the upper part. In the later stage of the display I noticed faint X at the anthelion indicative of the diffuse/Tricker arcs. I had no camera but my friend borrowed his camera equipped cellphone. Image quality is quite poor, but halos are still recognizable. Also Parry arc and 120 parhelia were present. Other halos were 22halo, parhelia, 22 upper tangent arc, parhelic circle, circumzenith arc, infralateral arc and supralateral arc. The display was noticed over large areas in Finland. More photos is here. Also see the photos by Arto Oksanen and Panu Lahtinen

Bright 120° parhelion over The Hague

Sunday, September 2nd 2007, The Hague, The Netherlands

After a cloudy morning, the low clouds broke up and both the sun and higher cirrus clouds became visible.

The appearance of the cirrus was an indication for me, to keep a keen eye on the sky. That policy was worth-while, because a short time later, at about 11.35 C.E.S.T., a part of the Parhelic circle appeared, together with a remarkably bright 120 deg. Parhelion, in NNE-ly direction. Both the parhelic circle and the Parhelion presented a clear brownish-reddish fringe colouring. Immediately, I fetched my mobile-phone-with-camera, and made the picture, accompanying this message.

Frank Nieuwenhuys

Elliptical halos over Deventer

14 August 2007 - At the edge of a large, smooth-structured Altocumulus bank, elliptical halos appeared at 1100, and from 1113 to 1120 UTC. In the first stage, the halo was complete and quite bright, although hardly coloured. It remained too short to get the camera ready. In the second stage, the halo was quite bright as well, and uncoloured, and sometimes partly covered by the continuously passing-over Altocumulus edge. Several photographs were able to be made (Nikon D80, AF-S Nikkor justed on 45mm). At 1113 UTC there were sections of two different elliptic halos visible. The inner remainded visible and was complete, even shining through the Altocumulus. The Altocumulus became increasingly dense and halos disappeared at 1120 UTC. Solar elevations from 51.7 to 51.9degs.

Peter-Paul Hattinga Verschure, Deventer The Netherlands

Pyramidal halos 8-14-07

After weeks of seeing no nice halo displays I was at work today on breaktime and I saw 22 halo and upper 22 deg tangent arc. I put my sunglasses on and I soon realized I had an odd radius display at hand. In all there was 9 deg. halo 18 deg halo and the outer halo who knows it could be 22 or 23 or a combo of both. The upper arc is convincing it looks sharp and I think it might be 22deg upper column arc but not sure. One photo is an original and the other has USM applied to make the halos stand out better. This is a good odd radius display for me but I know there is a lot better.

Complex displays in Eastern Europe

A series of complex halo displays occured in Eastern Europe between 27 March and 6 April. The first display in this series was seen in Vecsés, Hungary (observer: Ágnes Kiricsi). On 27 March at 13:30, after the appearance of the shining 22° and circumscribed halos, the parhelia started getting brighter and brighter, and together with them, a growing stretch of the parhelic circle came to sight ( 1 ). In about a quarter of an hour, as the clouds were passing towards the east, the 120° parhelion showed up on the left ( 2 ). The phenomena lasted until 14:10 with the complete parhelic circle visible for about 5 minutes.

The display continued until sunset with a 22° halo, parhelia, upper tangent arc, circumzenith arc and supralateral arc. In Vecsés, the clouds started thickening, but in Budapest the conditions got better at this time of the day. In a rather narrow stretch over the capital, a Tape arc was observed between 16:40-16:56. Images were taken by Alexandra Farkas and Tibor Hollósy ( 3 and enhanced 4 ). They did not see other halos formed by Parry oriented crystals, but 7 km to the north and only 3 minutes earlier, Márk Laczkó had photographed an upper suncave Parry arc ( 5 - 6 ).

In Hungary, there were two other observations of complex displays with complete or almost complete parhelic circles. One on 1 April (Ágnes Kiricsi in Vecsés), the other one on 5 April (Alexandra Farkas, Tibor Hollósy in "Remete" Gorge).

On 2 April, after a long time period, Marko Krusel also had an opportunity to observe a complex halo display in Estonia, nearby Keila. The peak time was 14:30, when the sun was 30.9 degree above the horizon and the sky was covered by cirrostratus haze. Besides all the common halos like 22° halo, upper and lower tangent arcs, parhelia, supralateral arc and CZA, he also got a bright upper suncave Parry arc, a nice full parhelic circle and 120 degree parhelia. A fragment of the infralateral arc was also seen on left. The show ended at 16:00.
Suprisingly the right side parhelic circle and 120 degree parhelion were the latest leavers ( 7 ).

6 April was a favourable day for the Czech Republic and Poland. The Czech Matej Grek (Ostrava-Dubina) and Martin Popek (Nydek) both photographed complex displays with parhelic circles and bright circumscribed halos. A 46° halo was also visible ( 8 - 9). On the same day, Jakub Marchewka also observed rare halos in Chrzanów in the south of Poland. He saw well-defined 22° halo with parhelia, circumscribed halo and full parhelic circle on cirrostratus ( 10 - 11 ). When he looked through the photos he had taken, he noticed a faint Wegener arc ( 12 and enhanced 13 ) and 46° halo ( 14 and enhanced 15 ). It was a first observation of Wegener in Poland and one of the first of 46° halos. On 20th February 1661 Johannes Hevelius observed the Gdańsk halo display and he described a 46° halo. If he was right and did not mistake it for supralateral arc and infralateral arc, Jakub Marchewka's observation is the second in Poland.

Text: Marko Krusel, Jakub Marchewka and Agnes Kiricsi