Monday, 31 October 2016

Diamond dust halos in spotlight beam in the evening of December 2, 2015


By Marko Riikonen and Olli Sälevä

Here are shown the rest of the photos from the night that yielded the second capture of the anomalous Wegener/Hastings. From the golf course parking lot, where we took those photos, we walked into the golf course, and were able to place the lamp even lower down.

The display was no more as good, but in the photo above and two below there is nevertheless again visible a short patch of Wegener/Hastings on top of the 22° halo. Whether this one has an anomalous curvature, is hard to say. Judging from the 46° stuff that is seen against the forest, the crystal orientation would rather be column than Parry, because it has the looks of a 46° infralateral arc, not Tape arc, which would be more spotlike.












The swarm shifted and we followed it to a field over the river. There we continued taking photos, as shown below, but that was cut short when the spotlight started flashing at 10 pm. The 60Ah car battery had run out of power and it was game over for the night.


It was painful because the conditions seemed to continue at least for the next five hours and probably even amping up as the temperature rose from -11 to -5 °C. Under clear skies such a warming would have killed the diamond dust, but now it was overcast and the clouds kept hanging low, meaning they were likely nucleated to ice by the snow guns.

From this on the winter’s halo hunt continued with two batteries, but on one cold night in January even that was not enough. That time, however, a helping hand was extended by the Ounasvaara ski center folks, who borrowed one of their batteries.

Sunday, 30 October 2016

Another occurrence of an anomalous Hastings/Wegener


By Aleksi Velhola and Marko Riikonen

In an earlier post we showed a photo of a weird downward curving patch of Wegener/Hastings. Here is another case that occurred 9 days later on December 2, 2015. This time we also got a nice comparison to normal “Wegstings” by superposing photos taken from the same camera position.

The anomalous Wegstings appeared on two occasions and was well visible to the eye. At both times the display was less brilliant than at peak stages, during which normal Wegstings was seen. Same was true of the earlier display on 23 November.

A closeup of normal and anomalous Wegstings appearances superposed to one image.

The crystal sample is interesting. Crystals range between plates and equidimensionals, which one would not expect from the strong column orientation halos in the display. It just adds to the ever increasing file of cases where the samples are not what would be expected. The dish was out long time, something like half an hour, so it represents all different stages of the display put together. However, column orientation halos were all the time present.




Saturday, 29 October 2016

Spotlight display with a strong Molianen arc (and a crystal sample)


After having been hunting diamond dust halos since darkfall, at 1am we withdrew along with disappearing crystals back to the apartment to sleep. But this did not mean calling it quits. The forecast was for the conditions getting better, so every one hour each of us woke up in their turn to check the situation.

At 4 am it was time to go – there were streelight pillars over the city. In 20 minutes we were sitting in car and five minutes later arrived to the golf course parking lot next to the ski center. From there we walked to the golf field and away from ski slope lights and stayed there until 7 am.

The display was not dazzling, but it had a Moilanen arc that was strong in comparison to other halos. Consequently, in the crystal sample we expected an abundance of crossed long plates, which are thought to be responsible for Moilanen arc, but they were very few. Perhaps they were small and did no fall in the dish in representative numbers. In general, not much crystals settled on the dish.

Another thing about the crystal sample was that it contained some pyramids, and indeed a short lived 9° halo was seen in the beam when our cameras were not yet ready. Pyramids are often found in samples, but unless they are numerous, they don’t translate to actual odd radius halos in the sky.

There was some variation in the topography at the location, and so for a change, we had the lamp above the camera for all photos. The date is 23 November 2015.

Marko Mikkilä, Jarmo Moilanen, Marko Riikonen









Spotlight display with a strong Molianen arc (and a crystal sample)


After having been hunting diamond dust halos since darkfall, at 1am we withdrew along with disappearing crystals back to the apartment to sleep. But this did not mean calling it quits. The forecast was for the conditions getting better, so every one hour each of us woke up in their turn to check the situation.

At 4 am it was time to go – there were streelight pillars over the city. In 20 minutes we were sitting in car and five minutes later arrived to the golf course parking lot next to the ski center. From there we walked to the golf field and away from ski slope lights and stayed there until 7 am.

The display was not dazzling, but it had a Moilanen arc that was strong in comparison to other halos. Consequently, in the crystal sample we expected an abundance of crossed long plates, which are thought to be responsible for Moilanen arc, but they were very few. Perhaps they were small and did no fall in the dish in representative numbers. In general, not much crystals settled on the dish.

Another thing about the crystal sample was that it contained some pyramids, and indeed a short lived 9° halo was seen in the beam when our cameras were not yet ready. Pyramids are often found in samples, but unless they are numerous, they don’t translate to actual odd radius halos in the sky.

There was some variation in the topography at the location, and so for a change, we had the lamp above the camera for all photos. The date is 23 November 2015.

Marko Mikkilä, Jarmo Moilanen, Marko Riikonen









Friday, 28 October 2016

The "leftovers" from the 23 November 2015 display in Rovaniemi


In three previous posts we have dealt with different stages of the 23 November display that had some interesting features, like an anomalous Hastings/Wegener arc and a possible 4th Tape arc. Here we show the rest of the material we got that night.


After the lunar display was gone, wind direction changed and we followed the diamond dust to a new location. As usual, there is only one place to choose from when temperatures are not very low and the new field we found ourselves in was less optimal than the earlier one, having a rather confined space and yellow streetlights nearby. But you photograph where you can.

The image above and two below show that it was overcast again, moon glowing weakly through the cloud. In the beam, the display was not nearly as good as it had been before, yet it was by no means poor – it is only because we had been just a bit earlier spoiled by a monstrous halo complex we didn’t feel that inspired anymore. Add to that the ever more demanding calls of the land of slumber (we had been up most of the previous night and not sleeping in the daytime either because halos wouldn’t let us), we packed it all up and headed for the caressing warmth of the indoors even though the display was still kicking on.



Lamp elevation is around 0 degrees in the three photos above.
Who knows what there would have been on the offing after we gave up, there was still plenty of night left. As were about to doze off, the stratus clouds started breaking and moon shining bright again. Any change in conditions means also change in halos, and this one may have been for the better, judging from earlier breaking of clouds which produced a major spectacle.



In the image gallery at the bottom there are also photos from the first action of the night, soon after it was dark. Crystals were collected and there were plenty of plates with internal structures.

Jarmo Moilanen, Marko Mikkilä, Marko Riikonen









The "leftovers" from the 23 November 2015 display in Rovaniemi


In three previous posts we have dealt with different stages of the 23 November display that had some interesting features, like an anomalous Hastings/Wegener arc and a possible 4th Tape arc. Here we show the rest of the material we got that night.


After the lunar display was gone, wind direction changed and we followed the diamond dust to a new location. As usual, there is only one place to choose from when temperatures are not very low and the new field we found ourselves in was less optimal than the earlier one, having a rather confined space and yellow streetlights nearby. But you photograph where you can.

The image above and two below show that it was overcast again, moon glowing weakly through the cloud. In the beam, the display was not nearly as good as it had been before, yet it was by no means poor – it is only because we had been just a bit earlier spoiled by a monstrous halo complex we didn’t feel that inspired anymore. Add to that the ever more demanding calls of the land of slumber (we had been up most of the previous night and not sleeping in the daytime either because halos wouldn’t let us), we packed it all up and headed for the caressing warmth of the indoors even though the display was still kicking on.



Lamp elevation is around 0 degrees in the three photos above.
Who knows what there would have been on the offing after we gave up, there was still plenty of night left. As were about to doze off, the stratus clouds started breaking and moon shining bright again. Any change in conditions means also change in halos, and this one may have been for the better, judging from earlier breaking of clouds which produced a major spectacle.



In the image gallery at the bottom there are also photos from the first action of the night, soon after it was dark. Crystals were collected and there were plenty of plates with internal structures.

Jarmo Moilanen, Marko Mikkilä, Marko Riikonen