Lascar display II

Another phase of the Lascar display. Three photos are stacked from sun elevation range of about 32° to 30°. Familiar halos are 23° and 20° plate arcs. Other halos are not so familiar.

Lascar display

This was seen on 27 November 1997 in Chile, on the foot of Lascar volcano, where Leena Virta and I photographed it. The image - that is stacked from nine slides - presents only one stage of the display. The photos were taken in 10 minutes interval, during which sun elevation change was from 25.5° to 23.5°.

The display contained some exotic halos, such as 28° halo. There seem to be also traditional pyramidal crystal halos, in this image 23° plate arc and pyramidal helic arc. However, what looks as 18° plate arcs are actually below the level of the sun (this was pointed out by Walt Tape years ago).

Halos on 6 November in Rovaniemi

The diamond dust that developed on the night of 5/6 November stayed until next midday. Here are two photos of what was seen in the daytime. The diffuse arcs were at times quite strong, showing up against buildings some 100 meters distant. But I did not manage to get a photo when they were at their best.

One more shot of 5/6 November in Rovaniemi

This view shows several "rare white arcs". On the right the long spectral arc is 46 supra/infralateral arc. Towards the middle of the image from top to bottom are helic, subhelic and Wegener arcs. Diffuse and Tricker anthelic arcs are seen on the left and also weakly a patch of subanthelic arc. On parhelic circle blue spot is in the center of the photo.

Another surface halo from Finland

On a couple of days there have been ground halos in Juva. It was best seen on a sportsfield running track. I stacked 45 images in Photoshop. Photographed with 10-mm and cropsensor.

Text: Jari Piikki

Diamond dust halos in Rovaniemi, Finland

Having kept a keen eye on the weather for quite a while Marko Mikkilä and I finally managed to spent a few days (or, rather, nights) in Rovaniemi shooting halos. We observed several interesting displays the best of which featured subhorizon Lowitz arcs. Similarly, subhorizon parhelic circle was captured by placing the light source to a negative elevation.

We observed superparhelia and several other divergent light halo forms such as CHA and 120 degree parhelia. Both of us got to see several personal firsts so we consider the mini expedition a success.

Amidst all the frenzy, we shot videos (1) inside the crystal swarm. Mikkilä's custom modified HID lamp proved extremely bright and useful in these conditions. We were able to illuminate objects several kilometers away with it.

We also sampled crystals during a Moilanen arc display (2).

The photos displayed (by Mikkilä & Luomanen) were captured between 15 and 17 November 2008.

Snow surface odd radii

Last friday I was on a first aid course in Köngäs and noticed on the snow surface a suspicious looking 22° degree halo. The lack of sharp inner edge reminded me of last winters snow surface odd radius displays.

So on a lunch break I went to a lake ice to photograph. There was only time for 79 shots, but that was enough to make 9° and also faint 24° halo appear. Given is also a mirrored version of the stack.