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I screwed up this one. The condidionts were on and I was waiting in Mustavaara for three hours for them to start the snowguns while there was actually diamond dust from Kontiolahti biathlon stadium snow gunning not far from Mustavaara. Eventuallly I saw the Kontiolahti swarm in the distance as I walked up the Mustavaara flank. After three km of driving I entered the diamond dust and got a couple of photos from parhelia against pine forest. The ice fog extended at least 12 km from the source, but I was still deep within. Who knows how far it reached.
2010. december 3., péntek
Spotlight halos from Mustavaara snowguns 23/24 November 2010
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The moon halos disappeared as the cloud got thicker and I headed back to Joensuu. The wind was even stronger now, with snowdrift and snowdevils on the road and snow dropping off the trees. On the way at the quarry, however, there was a swarm and I took there some photos with positive and negative lamp elevation. Nothing special, but the photos show nicely the effect of varying crystal tilts on halos. Eventually the swarm died off and moon was shining again surrounded by 22° halo in high clouds.
The moon halos disappeared as the cloud got thicker and I headed back to Joensuu. The wind was even stronger now, with snowdrift and snowdevils on the road and snow dropping off the trees. On the way at the quarry, however, there was a swarm and I took there some photos with positive and negative lamp elevation. Nothing special, but the photos show nicely the effect of varying crystal tilts on halos. Eventually the swarm died off and moon was shining again surrounded by 22° halo in high clouds.
Moon halos from Mustavaara snowguns 23/24 November 2010
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When it is windy you don't get diamond dust halos in Finland. For some reason (could it be that in still weather radiative cooling is stronger and thus relative humidity can rise to reach ice saturation?) there is not enought moisture in the air for ice crystal growth in windy weather. This night is was windy but I nevertheless drove 25 km to Mustavaara to check the situation. As expected there was no diamond dust and I was thinking of going back to Joensuu. Still it looked like it was on the treshold so I decided to wait. This paid off as eventually the ice fog from the snow guns starting spreading and 22° halo was seen in it. Further away the display was a bit better, with also parhelia visible (there was also high cloud in the background, which may have partly contributed to the display, in the second photo the 22° halo on the left is in high clouds). I tracked the cloud extent to 10 km from the source but at that time it was already receding, so probably it was wider at its best.
So this display broke the "no wind" curse for me in Finland. At polar areas where it is hardly ever calm, diamond dust halo displays seem to occur at any wind speeds.
When it is windy you don't get diamond dust halos in Finland. For some reason (could it be that in still weather radiative cooling is stronger and thus relative humidity can rise to reach ice saturation?) there is not enought moisture in the air for ice crystal growth in windy weather. This night is was windy but I nevertheless drove 25 km to Mustavaara to check the situation. As expected there was no diamond dust and I was thinking of going back to Joensuu. Still it looked like it was on the treshold so I decided to wait. This paid off as eventually the ice fog from the snow guns starting spreading and 22° halo was seen in it. Further away the display was a bit better, with also parhelia visible (there was also high cloud in the background, which may have partly contributed to the display, in the second photo the 22° halo on the left is in high clouds). I tracked the cloud extent to 10 km from the source but at that time it was already receding, so probably it was wider at its best.
So this display broke the "no wind" curse for me in Finland. At polar areas where it is hardly ever calm, diamond dust halo displays seem to occur at any wind speeds.
2010. december 2., csütörtök
Spotlight halos from Mustavaara snowguns 17/18 November 2010
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The moon halo display vanished as it got eventually overcast. It was still low stratus with occasional fog on the ground, but apparently the moisture just became too much for the snow guns' ice dust to nucleate a hole. Diamond dust nevertheless continued under cloudy skies and I turned on the spotlight. It was rather good, plate crystals still in charge and with negative elevation lamp (about 11° below horizon) there appeared several "super"-halos (equal to "sub"-halos when light is above the horizon). All were visible to the naked eye, the superparhelic circle at the superanthelic region was bright. At its best the superparhelic circle extended all the way to the superparhelia but I did not get that stage photographed. At the same time was also normal parhelic circle visible. I though of seeing a ghost of super-120° parhelion, but decided it was just white snow on the far hill. In the photos, however, super-120° parhelia are visible in a similar ghostly manner, so probably that was what I saw.
Getting these photos was mostly waiting. Mainly it was water fog, but then, for maximum few minutes at a time good crystal swarms swept by. In one exposure both water fog and diamond dust stage was captured so that there is also fogbow visible. In reality halos and fogbow were not much visible at the same time. Water fog and diamond dust don't just occur simultaneously. Eventually it got worse and I headed back to Joensuu. But on the way there was diamond dust at the quarry, 7 km as the crow flies from Mustavaara. So I took some photos there as well, climbing up a gravel mountain, leaving the lamp at the bottom and thus obtaining about 35° negative light source elevation.
The moon halo display vanished as it got eventually overcast. It was still low stratus with occasional fog on the ground, but apparently the moisture just became too much for the snow guns' ice dust to nucleate a hole. Diamond dust nevertheless continued under cloudy skies and I turned on the spotlight. It was rather good, plate crystals still in charge and with negative elevation lamp (about 11° below horizon) there appeared several "super"-halos (equal to "sub"-halos when light is above the horizon). All were visible to the naked eye, the superparhelic circle at the superanthelic region was bright. At its best the superparhelic circle extended all the way to the superparhelia but I did not get that stage photographed. At the same time was also normal parhelic circle visible. I though of seeing a ghost of super-120° parhelion, but decided it was just white snow on the far hill. In the photos, however, super-120° parhelia are visible in a similar ghostly manner, so probably that was what I saw.
Getting these photos was mostly waiting. Mainly it was water fog, but then, for maximum few minutes at a time good crystal swarms swept by. In one exposure both water fog and diamond dust stage was captured so that there is also fogbow visible. In reality halos and fogbow were not much visible at the same time. Water fog and diamond dust don't just occur simultaneously. Eventually it got worse and I headed back to Joensuu. But on the way there was diamond dust at the quarry, 7 km as the crow flies from Mustavaara. So I took some photos there as well, climbing up a gravel mountain, leaving the lamp at the bottom and thus obtaining about 35° negative light source elevation.
Moon halos from Mustavaara snow guns 17/18 November 2010
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This display was a result of low Stratus turning into ice crystals. It was right on when I arrived with car to the scene, which made me regret my idling in the comfort of indoors. The nucleating agent was the ice dust from Mustavaara snowguns. Essentially this created a punch hole in the cloud layer. All around this few kilometers wide opening it was overcast. Moon was three days short of full and an all sky plate crystal display was seen. The best of the crystal swarm moved back and forth and I tried to follow it with car.
This display was a result of low Stratus turning into ice crystals. It was right on when I arrived with car to the scene, which made me regret my idling in the comfort of indoors. The nucleating agent was the ice dust from Mustavaara snowguns. Essentially this created a punch hole in the cloud layer. All around this few kilometers wide opening it was overcast. Moon was three days short of full and an all sky plate crystal display was seen. The best of the crystal swarm moved back and forth and I tried to follow it with car.
2010. november 10., szerda
Superb Lowitz and helic arcs from the USA
I soon was seeing "sun dogs" on the parhelic circle. I then was clearly seeing the Wegener arc inside the parhelic circle. It was very vivid as with my eyes I could clearly see the rainbow colors. To be honest I never did see the Heliac arc before. I was flipping through pictures inside later and it simply jumped out. I was like, what is that arc..then looked it up.
The top of the 22 degree halo visually looked crazy most of the time. Very clear and colorful and odd arcing. I thought it was just an intense circumscribed arc in there but it didn't look placed right and like more was happening. ( 1 - 2 - 3 - 4 - 5 )
The show only lasted 30-40 minutes I'd guess. Then it was pretty hard to get any optics at all. What was strange was visually nothing much was changed about the sky. I was watching for hours so there were different periods of less contrail garbage blocking out the sun. I had friends in Omaha, 20 miles south, and Lincoln another 45 miles south of that, looking too. They never saw anything good. They watched till sunset too, but they also didn't get out as soon as I was and that was the best part. I wonder what I missed before I got out.
The satellite loop for that day may give the key ( 6 ). I'm located in eastern NE which is at the top center. It was much like the crystals you get right behind a blizzard in air just where it is clearing behind the storm. You can see a more puffy nature to the clouds, they pass and the ice crystals are left in the air. That stuff on satellite is below typical cirrus level/flight level...but still up there. It for sure was different than normal cirrus. A lot of that "cirrus" in the shot is left over form all the contrails. Once the sun got lower you could see the moisture/clouds clearly below the contrails. So anyway, probably worth noting the clouds coming across at the time were more along the lines of mid-level clouds/moisture.
Mike Hollingshead
2010. október 30., szombat
Superb diamond dust display in Austria
On 18 October 2010 a superb diamonddust halodisplay was observed at the meteorological station Sonnblickobservatorium ( 1 ) in the Austrian Alps (3106 m, 12°57’ E, 47°03’ N). Hermann Scheer, member of the meteorological team at the observatorium, took images of 13 different haloforms between 08:30 and 09:00 CEST (06:30 and 07:00 UT): parhelia, 22°-halo, 46°-halo, lower tangent arc, subsun, subparhelia, infralateral arc with Parry-infralateral arc, supralateral arc, parhelic circle, subparhelic circle, subhorizon Wegener arc and helic arc. ( 2 - 3 - 4 - 5 - 6 ) The images were taken at a sun elevation of 8,9° to 10,3° between 08:31 and 08:40 CEST, the file names indicate the exact time.
The brightness of the Wegener arc was incredible. Very interesting is the combination of Parry-infralateral arc with infralateral and faint supralateral arc. This part of the phenomenon is similar to an observation in the Czech Republic (26th of December, at Lysa hora in Krkonose (Giant Mountains)), described at Optické Úkazy v Atmosférè ( 7 - 8 ) Thanks to Tomas Trzicky for the links. And also in Ice Crystal Halos ( 9 ). In this very small area of the display we can see a 46°-halo, Wegener arc, helic arc and the subparhelic circle too.
The display was observed at the upper boundary of the stratiform layer; weather conditions: 06:00 UT - air temperature -6,8°C, air relative humidity 96%.
Credit to Hermann Scheer for giving the permission to show his images at Crystal Halos Blog under this licence: ( 10 ). Homepages of Hermann Scheer: ( 11 - 12 - 13 ). This diamond dust display is described on the page "Atmospheric phaenomenons observed in Austria" too: ( 14 )
Karl Kaiser
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