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> > > Speaking of antisolar iridescence: I haven't
> > > seen this term, or photos, in
> > > any optics book yet. Why is that? Antisolar
>
>The standard term is "glory"; look for that and you will see piles of
>examples in texts.
I am aware of the glory -- if you read my post again you'll notice that I
was actually mentioning "spurious glory rings" being the antisolar
iridescence. I'm sure that that is the cause of the effect. The point I
am trying to resolve is, since regular iridescence relates to the common
corona, and iridescence is separately discussed in the various literature,
why is antisolar iridescence not recognized. I think it is because not
many people observe it.
Anyway, the pictures are at:
http://www.weather-photography.com/tmp/w-422-00.jpg
http://www.weather-photography.com/tmp/w-422-01.jpg
http://www.weather-photography.com/tmp/w-422-02.jpg
http://www.weather-photography.com/tmp/w-422-03.jpg
The antisolar iridescence in the pictures is well away from the antisolar
point, about 20 to 30 degrees.
It's a bit challenging to detect the cloud irisation in the photos, but
it's there. Since antisolar iridescence can only be seen from the ground
when the sun is near the horizon, the spectrum of sunlight is limited to
the longer wavelengths, which is probably the reason why the colors are
not
so vividly pastel as the regular cloud iridescence near the sun during the
day. But if you are in an airplane, the antisolar iridescence can
sometimes be seen clearly, well away from the antisolar point - up to 20
or
even 30 degrees. However, as Les pointed out, the contrast and intensity
is rather low.
Harald
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