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Marko Riikonen: "Debate on Ellipticals/Bottlinger's" (Oct 19, 19:25):
> >Are you referring to the observation by Hakumaki and Nousiainen?
> >If so, i would like to point out that the vinicity of industrial
> >smoke doesn't prove anything about the origin of ice crystals (?)
> >causing the elliptical halo.
>
> You missed the point Timo. It is partly the same as yours:
> elliptical halos have been seen in various conditions. To
> point out only Altocumulus Virga and assume that that forms
> a some kind of proof for gyration is hardly a valid argument.
>
I had no intention to point out that altocumulus virga is the only valid
source for hydrometeros causing the elliptical haloes. I merely tried to
warn you not to draw any conclusions too hastily.
Are there any other observations of elliptical haloes in the vinicity of
industrial smoke plumes except that of Hakumaki and Nousiainen? Have you
considered the fact that Mr Nousiainen observed the phenomenom half a
kilometer from the pipe, whereas Hakumaki made his observation about
half a kilometer further away. The phenomenom itself (the halo) was
quite similar.
I wave no intention of crashing your argument against AC virga as the
only source, neither do I try to prove industrial smoke is not
responsible for the elliptical halo observed (and photographed) in this
peculiar case. I merely want to point out that IF the argument for
industrial smoke is based on this one observation alone, then it should
be noted there is really no hard evidence for it.
> The observed nucleations in nature have been essentially faster
> than in the laboratory experiments. Timo, have you seen in URSA
> headquarters for example the copy of the National Science
> Foundation halo study proposal by Tape (et al)? One of the points
> expressed there is the amazingly fast nucleation and growing of
> halo producing ice crystals in nature.
Can't argue against this, not my special field in atmospheric sciences.
However, I would like to point out that if the ice crystals causing the
elliptical halo originated from the plume, following three things must
have happened in a minute or so:
1) The water vapour must have cooled to the freezing point.
2) The nucleation must have taken place.
3) The ice crystals must have grown to a size where they are sedimented
from the plume.
also, considering the fact that there was some wind present, the plume
was clearly moving towards the observers, the ice crystals must have
fallen out from the plume even nearer the pipe. This is due to the fact
that small ice crystals fall rather slowly, thus an air flow of almost
any velocity can move them significantly.
>
> The whole issue will not last long if two things keep repeating
> themselves: such counter-gyration polarisation as observed by
> Sillanpaa and such colors as in photographs by Ruoskanen (1993),
> by Piikki (1996) and by Sillanp{{ (1996). Particularly Piikki's
> photographs are quite Devastating to reflection-based theories.
>
You got the point here. Forgot to say, I would like to see the photos...
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