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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
--
Juhana Hakumaki
NMR Research Group, A.I.Virtanen Institute
University of Kuopio, Finland
jhakumak_at_messi.uku.fi
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