Gary,
I think the confusion here comes from the use of yellow tinted sunglasses to
cut glare in hazy conditions. These sunglasses increase contrast by
filtering out blue light; haze is very small (about 1 micron) water droplets
and dust particles, which preferentially scatter short wave length (violet &
blue) light. The scattering intensity of the much larger (greater than 10
microns) Fog droplets is practically the same for all wavelengths, so yellow
light scatters just as much as white. Incidentially haze causes mostly
forward scattering (same direction as illumination source), while fog and
clouds cause mostly back scattering. This explains why the sky is so bright
on a hazy day and why the under side of cloud are so dark. For more info
look up Rayleigh and Mie scattering
http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html
Todd Osborn
B.S. Meteorology (class of '81)
----- Original Message -----
From: "Gary McCormick" <svgkm@halley.ca.essd.northgrum.com>
To: "Datsun Roadster List" <datsun-roadsters@autox.team.net>
Sent: Wednesday, February 28, 2001 7:29 AM
Subject: Fog Lights
> This may not be the last word on the issue, but FWIW, here's what I heard
back from the
> technical folks at Road & Track magazine on the subject of yellow vs.
white fog lamps:
>
> RTLetters wrote:
>
> > Gary,
> >
> > I talked to Dennis Simanaitis, our engineering editor, and he agrees
with
> > you that there has not been proven any advantage to using yellow lights
in
> > foggy conditions. Like you said, the only reason they seem like they
give
> > off less glare is because they are usually of a lower intensity, so the
> > reflection is less.
> >
> > Hope this helps,
> >
> > R&T
> >
>
> Gary McCormick
> San Jose, CA
> '70 2000 (doesn't have fog lamps, doesn't need 'em - doesn't run... )
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