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> Dear fellow observers,
>
> Such interesting discussion on elliptical halos! Thanks, I d
> definitely be willing to see and learn more on this topic. It s years
> since I was last updated on this issue. And to think that these halos
> have still managed to escape a 'definite' explanation!
>
> Being the co- observer and photographer of the 18.2.1988 ellipse in
> Kuopio, I would like to bring out some more detail, though, on the
> conditions on that day. I remember having walked from High School
> that day in a direction very much perpendicular to the heating plant
> plume, towards the more distal end of the vapor plume (Timo
> Nousiainen lived slightly closer to the proximal part. As I recall,
> there seems to have been no difference in ice crystal density along that
> distance (about 800 m), and the temperature might have been around
> -15oC. The crystals afloat were almost as if it was snowing but not
> quite so. It s hard to explain, I ve never since seen anything
> similar. I remember the clouds in the background to have resembled
> cirro(/alto)cumuli. I think they show in the slides.
>
> On the other three occasions that I ve observed an elliptical halo, the
> clouds have most resembled altostratus, and on every occasion there
> was light snowfall. Sadly I have no newer data, and I am no expert on
cloud
> types. Due to my own experience though, I feel inclined towards Dr.
> Traenkle s theory. I would be interested in learning more on the
> latest observations, either through this forum, or personally.
> Especially on the pyramidal crystals. :)
>
> Cheers,
> Juhana
>
>
At this point of the discussion I - Eberhard Tr"ankle - would like to
mention
that originally it was not my idea, that snow crystals are important.
If I remember correctly, Jarmo Moilanen told me in a discussion during my
stay
in Finland that snow crystals were observed by Finish observers during or
shortly after the appearence of elliptical halos.
I was sceptical. But, I build the styrofoam models to check this idea.
Indeed, I was very surprised, when I saw the stable fallmode of gyrating
snowstars for the first time in the staircase of the house I live in
Berlin.
Best regards to all of you. Eberhard Tr"ankle
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