There is no good reason why fog lights are yellow. Here is an
excellent explanation provided by Professor Craig Bohren of Penn State
University:


"First I'll give you the wrong explanation, which you can find here and
there. It goes something like this. As everyone knows, scattering (by
anything!) is always greater at the shortwavelength end of the visible
spectrum than at the longwavelength end. Lord Rayleigh showed this, didn't
he? Thus to obtain the greatest penentration of light through fog, you
should use the longest wavelength possible. Red is obviously unsuitable
because it is used for stop lights. So you compromise and use yellow
instead.


This explanation is flawed for more than one reason. Fog droplets are, on
average, smaller than cloud droplets, but they still are huge compared with
the wavelengths of visible light. Thus scattering of such light by fog is
essentially wavelength independent. Unfortunately, many people learn
(without caveats) Rayleigh's scattering law and then assume that it applies
to everything. They did not learn that this law is limited to scatterers
small compared with the wavelength and at wavelengths far from strong
absorption.


The second flaw is that in order to get yellow light in the first place you
need a filter. Note that yellow fog lights were in use when the only
available headlights were incandescent lamps. If you place a filter over a
white headlight, you get less transmitted light, and there goes your
increased penetration down the drain.


There are two possible explanations for yellow fog lights. One is that the
first designers of such lights were mislead because they did not understand
the limitations of Rayleigh's scattering law and did not know the size
distribution of fog droplets. The other explanation is that someone deemed
it desirable to make fog lights yellow as a way of signalling to other
drivers that visibility is poor and thus caution is in order.


Designers of headlights have known for a long time that there is no magic
color that gives great penetration. I have an article from the Journal of
Scientific Instruments published in October 1938 (Vol. XV, pp. 317-322).
The article is by J. H. Nelson and is entitled "Optics of headlights". The
penultimate section in this paper is on "fog lamps". Nelson notes that
"there is almost complete agreement among designers of fog lamps, and this
agreement is in most cases extended to the colour of the light to be used.
Although there are still many lamps on the road using yellow light, it
seems to be becoming recognized that there is no filter, which, when placed
in front of a lamp, will improve the penetration power of that lamp."


This was written 61 years ago. Its author uses a few words ("seem",
"becoming recognized") indicating that perhaps at one time lamp designers
thought that yellow lights had greater penetrating power. And it may be
that because of this the first fog lamps were yellow. Once the practice of
making such lamps yellow began it just continued because of custom."


Also, take a look at the following web site:
http://www.gi.alaska.edu/ScienceForum/ASF5/593.html

Dr. Lawrence D. Woolf
General Atomics
================================================== =======

 

Are you serious?
Here are some "real" cars that have those "ricey" fog lights on the bottom...

Aston Martin Vanguish


Dodge Viper (venom)


Ferrari 550 Marellano


Mercedes McLaren SLR


Maybe you've heard of some of them?

 

It's the old traditional foglights that are amber in color. Studies done in Europe about 15 to 20 years ago showed that the amber beam created a false depth perception, and most abandoned the amber at that time, instead, focusing on the actual beam pattern. As long as it's not blue, normal white or slightly off white (that many here complain about), allows the best penetration of light through the fog.

Studies have also shown that as long as the center of the light is below 24", it penetrates the less dense lower fog layer quite well, and can be focused with the cut-off slightly downward. The lower you mount the fog lights, the less distance you can effectively focus the light without compromising glare. Also, mounted lower sets up odd shadows that are greatly influenced by dips in the road, etc.

The foglights in our Gs are a very good compromise, even though they don't look as cool.

 

You can penetrate fog as much as you want, but unless the scattering is controller, any light would be useless. Case in point if you were to point a 10,000 candle power spot light right into the fog you still won't see a thing. However if you pull out a 500 candle flash light you might get better luck as you get less scattering and more contrast.

 

Daniel Stern's article about fog lights. Worth reading

http://www.danielsternlighting.com/t...fog_lamps.html

 

This guy can't back up anything he says. Salesman pitch!

 

I beleive that fog lights were originally made- not to penetrate fog but so that other drivers could better see you.

 

What's that at the top of the license plate? A jammer of some sort??

 

thats what fog lights should look like...

 

laser diffuser on the passport or escort system ZR something I think?

 

just get the kenstyle bumper

 

Those aston martin fog lights are a great example fog lights are not ricey. They are on many luxury cars, including the 3 series. I expect infiniti to have them standard on the '07 model.

 

Madchef, Don't even bother with that guy. He likes to run around and rag on people calling everything rice because he's very cool and he knows what all the hip things are and what all the ricey things are. Now we'll all just wait around for his explanation on what he really meant by that to cover up since now everybody is going to give him crap for saying something like that.

Don't even waste your time with him.

 

thats looks like an easy pass....used for tolls in the tri-state area.. no waiting to pay...

 

Reflected yellow light is less of a strain on the eyes than other color light. It does not "cut through" the fog.