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Hi all,
> I for one of us ...I still don´t believe the standard interference is
> anywhere near the solution. Why so? Follows four reasons.
I must agree with Marko. The "twinned bow" really does not look
like a supernumerary bow. It is more like a reflection rainbow,
but then again the source of reflected light would have to be
very close to sun to this small separation. It also seems like
the two bows do not merge at horizon, as it would be if the
reflection came from a horizontal surface.
I don't know if you could get a reflection like that from a
tower of a catethral that just happens to be very close to
sun (this would explain the small separation and also the
merging above horizon), but it seems to me that for this to
be realistic explanation with sun that much above the horizon
the tower would have to be pretty close to the observer.
That would then mean that the raindrops close to the observer
and far away from the observer would see the reflection geometry
differently and thus the location of the reflected bow would
depend on the distance from the observer. This does not seem
to be the case.
Of course, the rainfall could be limited to a very small area, but
this just seems too far off to pass as a valid explanation. At least,
that's my feelings at the moment. That pretty much leaves the
nonspherical drops. It is well known that most raindrops are not
spherical. The problem is, different raindrops have different shapes
(varying amount of flattening depending on the size, varying
orientations depending on wind shear, oscillations depending on lots
of things), and thus the rainbows they produce are all different. This
averages out as white diffuse lighting.
So, in order to see an effect from nonspherical drops, we would have
to have a predominant shape and orientation for the nonspherical
drops. I have been under the impression that this would be very
unlikely. I cannot remember any studies about this, though, it
might just be that this has been overlooked in the absence of
observations. Interesting...
Timo Nousiainen
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