Amber fog lights (was Night Flaming)

[Luis A Marques <marques@ti.com>]

I have recently seen a great deal of posts regarding the validity of
amber fog lights etc. so I thought that I could contribute with some
objective information.  While I was in Georgia Tech, I took a course in
ilumination and, if I remember correctly, having amber fogs makes a lot
of sense.  The reason for this is light reflection and refraction.  Due
to the size of the water particles, some colors of light (with different
wavelenghts are "bent" or "reflected" more than others when they go
through fog.  This is how rainbows are formed BTW.

Amber light seems to be less affected by this due to the particular
wavelenghth and the net effect is that more lumens find their way to the
point they were intended to go.  White light, on the other hand, has
energy in all wavelenghts, kind of many bulbs of different colors all on
at the same time.  The yellow/amber portion should go though fog
relativly unaffected, but all the other components are reflected back to
the driver, or redirected into some random useless direction.

So the net effect is that, although the amber lens blocks 1/3 of the
light, the lumens that do go through the lens iluminate their intended
target, whereas with the white light, only 1/2 of it reaches its
intended target and the other half is reflected back or redirected into
the surrounding scenery.  If you put higher wattage bulbs on clear fogs,
you would simply be blinding yourself more!  So I guess that the answer
is that for really thick fog, amber is the way to go, but if you use
your "fogs" to drive on light fog / fogless nights, clears are more
efficient.

Hope this helps bring some "light" into the subject.

Luis Marques
MSEE
'87 4Kcsq