Two diamond dust displays in Finland

Miika Karppinen photographed this display in the town of Kajaani on 8 March this year. Upper sunvex Parry arc and 46° Parry arc are weakly present ( 1 ).

The other display occurred on 26 October 2006 in Salla ( 2 ). Photos were taken by Jani Päiväniemi. Under the circumzenith arc there is a patch of 46° halo, which could be indication of 46° contact arc. First convincing photos 46° contact arcs were taken three days later in Muonio ( 3 ).

Both Kajaani and Salla displays were captured with cell phone cameras.

Wegener Arcs in Finland

Long absence of rare high cloud halos in Tampere skies was brought to a sudden end by a complex display on 2 May 2008. Singly and Parry oriented columns played the key roles: among the more common halo forms the display featured an upper suncave Parry arc and Wegener arcs.

Sun elevation was ca. 27 degrees. Both photos are stacked images (no longer than 5 minutes' time period for each). Below them contrast enhanced versions are provided. Also, larger images are available online ( 1 ).

Complex displays in Eastern Europe

A series of complex halo displays occured in Eastern Europe between 27 March and 6 April. The first display was seen in Vecsés, Hungary (observer: Ágnes Kiricsi). On 27 March, after the appearance of a bright circumscribed halo, a growing stretch of the parhelic circle came to sight ( 1 ) and 120° parhelion showed up on the left ( 2 ). The parhelic circle was complete for about 5 minutes.

Close by in Budapest, a Tape arc was observed in the evening. 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 of them and only 3 minutes earlier, Márk Laczkó had photographed an upper suncave Parry arc ( 5 - 6 ).

The next Hungarian observations of complex displays with complete or almost complete parhelic circles were on 1 April (Ágnes Kiricsi in Vecsés) and on 5 April (Alexandra Farkas, Tibor Hollósy in "Remete" Gorge).

On 2 April, Marko Krusel had an opportunity to observe a complex halo display in Estonia, nearby Keila (see image on top). Besides all the common halos, he got an upper suncave Parry arc, a full parhelic circle and 120° parhelia. A fragment of the infralateral arc was seen on left. The show ended with the parhelic circle and 120° parhelion as 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 ). In southern Poland Jakub Marchewka observed a display with full parhelic circle in Chrzanów ( 10 - 11 ). From the photos 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. The latter was described by Johannes Hevelius on 20th February 1661 in Gdańsk, but it is likely that supralateral and infralateral arcs were the main contributors to the phenomenon.

Text: Marko Krusel, Jakub Marchewka and Ágnes Kiricsi

Subsuns from space

The publication of the Mars halo on this site stimulates me to dig in history. On 27 April 1975, I saw by change a picture of a subsun taken from space ( 1 ). It is here on the frontal system on the right of Greenland. It was taken by the satellite ESSA 8, which was the last weather satellite that took real pictures of the Earth rather than being a scanning platform. Only a few months later, ESSA 8 was lost, so I had been very lucky. The discovery of the subsun on a satellite picture gave me the same sensation as the discovery of the subsun on Mars, 31 years later.

In 1985, I got another subsun taken from space (see photo on top), taken by the Dutch astronaut Ockels from the Challenger space shuttle during its last flight before the crash. The subsun is visible over the Netherlands, viewed upside down. Interestingly, the astronaut had overlooked the subsun despite the fact that I had prepared him for this possibility. He only saw the thing when he gave a slide show and I put his attention to it. Note its white colour compared to the sun’s reflection in the sea. Contrary to the ESSA 8 subsun on which I wrote a short paper in Weather, I did not publish this one.

Text: Günther Können

An unknown halo and other displays by Jukka Ruoskanen

Jukka Ruoskanen has scanned his best halo slides ( 1 ). The material spans from year 1988 to 2005 and includes several displays of interest. Some cases are rather puzzling, like the one shown above, photographed on 23 December 2001. It contains strange pillars next to sun pillar. Explanation for these arcs is not known.

Subsun and Bottlinger's ring

Dmitry Savvateev observed a subsun in 2006 in the Khibiny Mountains (Kola Peninsula, part of the Murmansk region). This subsun, however, seems to be accompanied by a much rarer halo: Bottlinger’s ring. Even though this case is a marginal one, the elliptical halo appearing around subsuns is so infrequent that the photo is worth showing here ( 1 ).

Just as elliptical halos formed around the Sun, Bottlinger’s rings can also be of one, two or three ellipses. The 1997 photo taken by Frank Wächter shows multiple rings ( 2 ), in the Khibiny picture, there is only one ellipse.

Display in Yuzhno-Sakhalinsk

Dmitry Kuznetsov saw this complex display in Yuzhno-Sakhalinsk on 1 April 2007.
The vertical arrows in the photo denote the Wegener arc and the horizontal arrows point at faint helic arc. Dimitry described also subanthelic arc, but it is located outside the photo. More photos are also available ( 1 ).

Halo vs glory

The photo above is intended to be food for thought, as it shows a rather controversial phenomenon.

Mónika Bodó took this picture on 27 March 2008 between 16:43 – 16:46 on a flight from Athens to Budapest. As an air hostess, she flies several times a week, and very often photographs subhorizon halos and glories. This was the first time, however, when she saw such a phenomenon. For comparision, the original version of the above photo ( 1 ) and another image are also available ( 2 - 3 ).

The bright spot in the picture is at the antisolar point, the location of both the glory and the "subanthelion". A short time earlier, the shadow of the airplane had been photographed ( 4 ) and it was exactly at this point where the brightening developped. On the other side of the airplane, the bottom of the 22° halo, subsun and subparhelia were visible ( 5 – 6 ).

When the "subanthelion" is photographed, it tends to appear where the diffuse anthelic arcs forming a large X cross the subparhelic circle, and the brightening seems to be caused by the meeting of these halos. On 7 August 2006, Francesco De Comité took a photo of these antisolar halos, and there the shape of the "subanthelion" is clearly a square, thus suggesting that it is not a separate halo form, just a bright spot created by the crossing anthelic arcs ( 7 ). Another image was taken by Susanne Danßmann on 3 June 2006 ( 8 ), and one can be seen in Walt Tape's Atmospheric Halos (page 71).

What makes Mónika Bodó's observation very interesting is that even though the spot looks like a halo, the subparhelic circle does not show up in the images, and there are no other halos visible in the antisolar region. If it is really a halo, her photograph seems to show one not caused by the crossing of these arcs.

There have been other observations of a single bright spot at the antisolar point, often taken as a distant glory. It might be, however, that it is indeed an independent halo form. So far no sufficient explanation exists, suggestions and opinions are welcome.

Two hour long elliptical halo display on 23 March

While working on a wood bowl in my workshop I noticed a lot of Altocumulus clouds that were turning into ice crystals. That meant a chance of elliptical halos. I took my camera, went for a walk, looked up and there actually was an elliptical halo! I ran like mad to get a macro lens and then used a telephone pole to shield the sun while shooting.

After about 10 minutes the halo was gone but I kept a vigil on the sky. Patience was eventually paid off as more dissipating Ac cloud moved in and the display came back.

I later positioned a large wood stick with lens case to block the sun and laid on my back and watched the show. The magic really began when a large Ac fragment passed in front of the sun and turned into ice crystals. It showed three elliptical halos at once, sharp and bright and they were colored like the classical halos ( 1 - 2 - 3 ).

The display lasted for two hours. One thing I noticed while laying on my back and taking photos was that the ellipse would start out large and then gradually shrink.

46° halo on snow surface in Juva

On 22nd March Jari Piikki photographed a 46° halo on snow surface. He took 20 photos and stacked them to come up with a photo above. The sky is from a single frame.

Two halo days in the northern part of the Czech Republic

At the weekend of 15 – 16 March, observers in the northern part of the Czech Republic had some opportunity to see rare halo phenomena. On 15 March, in the afternoon, fine cirrostratus came from the west, and subsequently bright halos appeared.

Patrik Trncak took a series of photos of the display. The most uncommon halos that he observed were the Wegener arc, which crossed the parhelic circle; and the Tricker arc, which was noticed afterwards on the images processed by Registax ( 1 ).

The next day, the situation was similar, but the Wegener arc was brighter and the cirrostratus clouds lasted for a shorter period ( 2 ).

I (Martin Popek) didn’t have such good luck but I could also observe some interesting halos. On the first day, a nice suncave Parry arc was visible, which shows well on the stacked images. By the bright parhelia, Lowitz arcs appeared, and after a long period of time I saw an infralateral arc, as well ( 3 - 4 ).

On the second day, the halos were less numerous. There was only one that is not so frequent: a faint 46° halo ( 5 ). Later I observed an interesting lunar display, too, including a diffuse 9° halo ( 6 - 7 ).

Text: Martin Popek, Lukas Shrbeny

22° halo on snow surface

Sirkka Sario took this photo in Lake Jerisjärvi, Muonio, on 5 March. Another photo is also provided ( 1 ).

Distinction of 22, 23 and 24° halos from snow surface

A broad 22° halo is observed in most odd radius displays. One factor explaining the broadness can be simultaneous occurrence of 22, 23 and 24° halos, or any combination of two of these halos. As we know, separation between 22° and 24° halos is detectable, but 23° halo has not been distinguished from the other two so far.

In the image above all the three halos are separated. This was made possible - in addition to having a suitable display - by stacking an extensive amount of images of a snow surface display. Using Rexistax, total of 379 frames were stacked and the resulting image was further stacked with its mirror image, essientially doubling the frames used. The separation of the three halos is seen also in non-mirrored image ( 1 ).

9, 18, 20, 35 and 46° halos were present as well. The first three are visible in the above image, which is a close up of 8 mm fisheye image. The 9° halo, of which only the lowermost part is seen, is overexposed. An image with only minor digital enhancement is given for comparison ( 2 ).

Three versions of full frame image show the 35 and 46° halos ( 3 ). A single frame ( 4 ) reveals the true nature of the display: it was nothing a passer-by would notice, and to me it might not have been any special unless I had known that day earlier in the same place odd radius halos were observed ( 5 ).

The photography was done on river ice in Rovaniemi in February. The method was to take 3 to 5 photos from different heights by adjusting vertically the tripod central bar and then moving the tripod some 20-30 cm and again taking a set of photos, and so on. This was faster way to obtain large number of photos from different positions than moving the tripod after each shot, as was done day earlier.

Samples of snow surface crystals were photographed in the location as darkness was approaching. Pyramidal faces were abundant ( 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 ).

The issue of pyramid crystal formation temperature was addressed in the discussion of the previous day display. Again the temperatures were not that cold, previous night was around -10 °C and it was cloudy. It cleared up in the morning and minimum temperature in the official measuring point of Rovaniemi center was -12 °C during the photography soon after midday.

It may be that snow surface presents a special situation concerning the pyramid crystal formation (and maintenance) temperatures. There is some evidence in the literature that pyramid crystals can exist on snow surface even at as high temperatures as -2.5 °C.

Whether that is really the case, it is nevertheless good to keep in mind that odd radius halos may exist on snow surface in “unconventional” temperatures and they may be much more common than we have known. However, these displays may not be easily recognized as special and stacking might be needed to visualize them.

Two diamond dust displays near Moscow

On 21 February ice crystals filled the air in Rumyancevo, a suburb of Moscow, and a halo display with relatively strong Moilanen arc was photographed by Alexandr Yakovlev. One of the photos, with unsharp mask enhancement, is shown above. Another photo is also given ( 1 ).

A year earlier, on 1 February 2007 Yakovlev photographed a diamond dust display with subsun and subparhelia from the 7th floor of a building ( 2 - 3 ). In the photos Moilanen arc is also present faintly. An unsharp masked image shows it better ( 4 ).

The original images of both displays are available on my blog ( 5 ).

Diamond dust display in Dolni Morava

On 29 December 2007, Radomir Vondra observed a complex diamond dust display above an inversion cloud layer. He was walking to the ski slope in the village of Dolni Morava, when he saw the halos between 12:30 and 13:00. The elevation of the Sun was about 15 degrees above the horizon, and the dominant phenomena that first appeared were the parhelia and a bright circumzenith arc. Later, after the sky got clearer, a suncave Parry arc appeared above the upper tangent arc. An unsharp masked version of the photo is also available ( 1 ).

On the same day, Matej Lebl observed well-defined parhelia in Rokytnice nad Jizerou ( 2 – 3 ).

Text: Martin Popek, Lukas Shrbeny

Moilanen arc in Zaton, Sumava mountains

On 3 February, Milan Osecky observed a diamond dust display with sharp Moilanen arc by the village of Zaton. The halo was seen during sunrise, when the Sun was about 4° above the horizon. The phenomenon lasted approximately 8-10 minutes, starting at 8:05 and disappearing completely by 8:15. Also a diffuse sunvex Parry arc was observed, which was a bit difficult to distinguish from the upper tangent arc due to the fuzzy border between these two arcs.

On the same day, Martin Nekola saw halos on mount Svorova in the Krkonose mountains. The photos show 22° halo, parhelia, pillars, upper tangent and infralateral arc ( 1 – 2 ).

Similarly, Tomas Trzicky in Jizerske hory observed well-defined pillars and upper tangent arcs in the light of street lamps ( 3 ).

Text: Martin Popek, Lukas Shrbeny

Reflection subsun in California

On 1 February, Steve Sumner in Auburn, California, observed a peculiar phenomenon in the sky. A bright elongated spot, which was apparently not lit directly by sun rays, occurred in front of an Altocumulus cloud. In the photo the Sun's rays projecting downwards from small openings in the cloud layer reveal that the Sun is positioned behind the cloud at the same location as the spot. The other photo of the display should stand here, as well, for comparision ( 1 ).

This phenomenon is the reflection subsun, a rare halo of which only two previous documentations are known. Its formation involves two reflections from horizontal surfaces: the Sun rays are first reflected on a body of water, and then again on plate crystals in the sky, which precipitate from the Ac cloud that blocks the Sun. This way the reflection subsun is seen just where the Sun should be.

Identifying the reflective surface was not obvious in the beginning for Sumner. "I could not figure out for a long time where the body of water might be that would reflect the sun in such a way that the halo could appear," he wrote. Then he remembered a place called Yolo Bypass, a large area to the west of the obsering site that is designed to flood during the winter and spring. "Due to the heavy rains we have experienced over the last several weeks, the bypass has been filled with water, and that must be the source of the required reflective surface," Sumner said.

In the map linked, the green arrow marks the point of observation, the yellow line starting there shows the Sun's direction, and the large blue area that it intersects is the Yolo Bypass ( 2 ).

Knowing that the Sun was at 6.5° elevation during the observation, and assuming that the Yolo Bypass at 56 km from the observing site was the primary source of light for the reflection subsun, Sumner calculated that the ice crystals were at about 3500 meter elevation, which is an agreeable value for Ac clouds.

Sumner’s photograph adds the third documented case of reflection subsun. Earlier, in Finland, Jarkko Korhonen had photographed such a halo in Oulu in October 1998, and then Jenni Elina Holopainen on 18 May 2006 in Pyytivaara ( 3 ).

Stacking an odd radius display on snow surface

For some years I have been waiting to get to employ stacking technique for snow surface halos. Last weekend the chance finally came along, as a moderate display appeared on two consecutive days. Here I present the results from the first day.

The image above is stacked from 118 images which were taken on a frozen river in Rovaniemi. Between each shot the camera, which was on tripod, was moved some 20-30 cm sideways. This serves to decrease noise of the snow surface in a similar manner as cloud movement decreases the noise in stacking of sky halos.

Already on the spot I thought of seeing double structure in 22° halo, indicative of the 24° halo, but was not certain of that until two hours later, when I came back with microscope and saw an abundance of pyramid crystals among normal crystals in samples taken from snow surface ( 1 - 2 - 3 - 4 - 5 - 6 - 7 ). In the above displayd stacked image the 24° halo is conspicious and also a close up image is given ( 8 ). 24° halo is seen also weakly in single unmanipulated images ( 9 ).


9° halo, which should be always occurring with 24° halo, is not visible in single images, but appeared in stacked image, and is seen perhaps best in an image that has only light unsharp masking ( 10 ). Heavily unsharp masked version resulted in 35° halo appearing faintly ( 11 ). At 86 frame stage I could not yet detect it, so additional 32 images made a difference.

In sky displays 35° halo is always associated with 20° halo because they are closely related in formation. As a thumb rule, one can have 35° halo if 20° halo is intense enough.

Here, however, it seems that there is no 20° halo or at most a ghost of it is present. Possibly the alternate pyramid faces, which make the 35° halo, are represented in the special snow surface situation in significantly greater proportion in relation to opposite pyramid faces, which make the 20° halo.

The lowest temperature measured at the official station in the city center was -12°C at 9 in the morning, three hours before I noticed the phenomenon. This is not quite enough for pyramid crystal formation as far as airborne crystals are conserned, which start occuring below -20°C.

However, down on the river ice away from the city center and especially on the few centimeters above the snow surface (clear sky) it can have been cold enough for pyramid crystal formation. Could be also that snow surface presents a special situation where not as low temperatures are required as with airborne crystals.

The crystal photos are all in same scale, the width of each square is approximately 0.6 mm.

The next day the display looked slightly different but pyramid crystals and odd radius halos were still present. I took 350 photos but have not worked on them yet.

Snowgun jewel from two years back

The morning of 16th March 2006 offered a perfect ending for skiing holiday week for Hinkka family, when a magnificent diamond dust halo display interrupted their outdoor activities near Himos ski resort. Markku Hinkka drew camera out and started shooting the sight. According to his story at least a 120° parhelion along with bunch of other halos was in the sky. However, he did not photograph these due to their less appealing appearence compared to the halos in the vicinity of the Sun.

Markku describes the weather being windless and "very foggy". The temperature was around -10°C. The snowguns were in operation and the halo was visible at least from a distance of 150 m up to 1,5 km from them.

The accompanying image is a collage of several individual photos taken by Markku Hinkka. In the process of making the collage the perspectives of some original photos have been twisted in a very violent manner. In this case the purely illustrative purposes justified the manipulative actions, but if any measurements or comparisons with simulations are intended, such twistings are highly inappropriate. The writer takes full responsibility for these twists.

Snow surface display with 9° and 24° halos

Sometimes a surface halo can be more than a couple of colored crystals forming a vague half circle on the snow. Such was the case on 8 January 2006 in Juva, where Jari Piikki photographed the display shown above.

22° halo is the dominating feature, but closer look reveal also halos from pyramid crystals. In darker version of the same image 9° halo is visible and a short patch of 24° halo is seen on the right where the 22° halo meets the forest ( 1 ).


Earlier, an odd radius halo had been observed on snow surface in Germany, where Richard Löwenherz saw 24° halo accompanying the 22° halo on 10 December 1998 ( 1 ). On 3 December 1986 in Kuopio, Finland, Juhana Hakumäki observed 9° and 22° halos on frosty window. The 22° halo was reported to have double spectrum, an indication of the presence of 24° halo.

Crystal photos from surface halo displays are scarce and as far as I know none are available from the displays with odd radius halos. However, pyramid crystals have been sampled from snow surface. At South Pole in December 1998 Jarmo Moilanen decided to have a look at the snow surface composition under a microscope, and to his surprise saw pyramid crystals ( 1 - 2 ). Unfortunately sun was too high to see the possible odd radius halos.