Tuesday, December 04, 2007

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.

5 Comments:

Blogger Jukka Ruoskanen said...

Last week also people in Southern Finland got to enjoy freezing temperatures for a few days. After what Marko has been doing up North makes last week's events look very dull although it was nice experience while it lasted. Few photos are in here. Now the temperatures are above 0C, but the equipment are ready for the next time...

04 December, 2007  
Blogger Marko Riikonen said...

Good display and good account Jukka. Yes, the mental stage is always the same. But it sounds you had time to enjoy the sight. I am envious.

04 December, 2007  
Blogger Michael Ellestad said...

Wow Marko I like to see that same display with an elevation of 22 degrees so you can see the parhelic circle and the 120d parhelia arcs. Keep up the good work on them divergent light source halos, its nice there is more attention being focused on them.

04 December, 2007  
Blogger Ágnes Kiricsi said...

It is so exciting to see what a cornucopia this new lamp has opened up. Jukka, you shouldn't underestimate your display, either. It is a very pretty one and I enjoyed reading your account. I'm wishing you for this winter many diamond-dusty days Riihimäki.

To me, Marko's photo of the antisolar arcs at 0° elevation light source still look like forming the outlines of a ruminant skull :)

05 December, 2007  
Blogger Claudia Hinz said...

I can't say something, I'm complete specheless ...

05 December, 2007  

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