fairenough

Setting appearance and cosmetic uses aside, I have heard frequently that yellow foglights (of equal type and wattage of course) provide superior poor-weather visibility. The concepts behind that idea vary depending on who you ask, including such notions as "better fog penetration" to "less reflection" etc. But after searching AudiWorld and the WWW in general, I have found a lot of people that dispute the idea. Some of the pertinent links I've found are below. I recently was just about to pull the trigger on some expensive PIAA H7 yellow halogen foglight bulbs but thought twice once I discovered the debate. Does anyone here know where I might find some more definitive answers to find out if yellow foglights are indeed better than white or other colors?

Please no flames, I've done searches and have some scientific knowledge myself, I'm just looking for additional information to evaluate.

Thanks for your input!

<a href="http://cartalk.cars.com/Columns/Archive/2002/February/08.html">cartalk</a>

<a href="http://www.gi.alaska.edu/ScienceForum/ASF5/593.html">scienceforum</a>

<a href="https://forums.audiworld.com/s4/msgs/422442.phtml">audiworldarchive1</a>

<a href="https://forums.audiworld.com/s4/msgs/303661.phtml">audiworldarchive2</a>

<a href="http://www.vclassics.com/archive/lightprn.htm">vclassic</a>

<a href="http://lighting.mbz.org/tech/lights/fog_lamps/fog_lamps.html">lightingmbz</a>

MichaelTM

first - mount the lights as low as possible, so light goes *under* fog

second - yellow light is better as reflection from tiny droplets of water (what fog consists of) supposedly creates less of a barrier for your eyes

don't ask me - I know nothing about this, I learned it long time ago and go by this rule until proven otherwise

AxelS4

Daniel Stern has a lot of info on his web site. Bluer spectral components generate more backscatter in fog which is a pretty homogenous distribution of water droplets of a pretty homogenous size. Yellow lights do not really help a lot in terms of added visibility, it is more a perception issue. Fog is completely intransparent for UV light, whereas infrared penetrates fog quite well, if you want to frame the extremes.

Steve Trac, Sec 303

PIAA H7 fog bulbs? Do you have a link or more info Brian?

nosey

how does fog have blue in it??even if it was its not like yellow light will shine right through the "blue fog" giving better contrast thus better vision right??
jus cuz water in the ocean in bluish doesnt mean that water molecules are blue...light no matter color is still going to shine and reflect off any surface, even the water particles of the fog...

wat i think fog lights do is that they jus shine at a very low height to shine light at the road below so that they dont reflect that much light from the fog as compared to the high beam and even low beams...

well thats my personal opinion...so i dont think yellow fogs are better...they might be just as good as the white ones or maybe worse...

but i do like them hehe =)

fairenough

<ul><li><a href="https://forums.audiworld.com/s4/msgs/1143627.phtml">https://forums.audiworld.com/s4/msgs/1143627.phtml</a</li></ul>

fairenough

To me, if you say UV light is completely reflected by water droplets while infrared is completely absorbed (big assumption, but let's let it play out), then it's a frequency dependent phenomenon and then it may be worth pursuing different foglights depending on their color/wavelength of light emitted. Guess I better dig out my old physics and optics books...

BTW, who is Daniel Stern? I'll have to do a search.

xr8edS4

.

MichaelTM

however: ALWAYS keep your hose in check. ALWAYS.

fairenough

The conclusion reached by Daniel Stern seems to be about the best so far in my opinion.

<a href="http://newton.dep.anl.gov/askasci/phy99/phy99xx4.htm">askascientist</a>

<a href="http://lighting.mbz.org/tech/lights/light_color/light_color.html">danielstern</a>