unwiredadventures wrote:I drive up in the San Bernardino several times per month.
Several times each winter I find myself in complete whiteout and extreme fog conditions.
Which is the best light, color, etc. to use in these conditions?
This is a topic I could discuss for hours, and a complete discussion isn't possible in a post. But here is some basic information that might help:
Fog lights, regardless of the light color, are designed to illuminate the area under the fog (which usually sits a couple of feet off the ground), and does not penetrate the fog as some think. No automotive light will shine through water vapor. The idea is to light the ground under the fog to help make the road more visible to the driver. A fog light distinguishes itself with its light pattern, which is wide and flat, with a sharp upper cut-off to prevent reflection back at the driver. Fog lights, because of their unique pattern, are also used as cornering lights, as the wide pattern helps the driver to anticipate curves on mountain / winding roads, and to better see the road boundaries.
Fog lights are available in both yellow and white - and while the benefits of either can be argued ad nauseum, it generally boils down to personal preference. Some feel the yellow light helps reduce the reflected glare, making the light easier on the driver's eyes, and the light pattern easier to discriminate.
Others find the yellow coloring distracting, and prefer the purer white color to prevent eye fatigue. I feel you should try both, if possible - maybe drive in someone's vehicle that has one or the other, and decide which works best for you. I have used both over long periods of time, and find both work well - with little fog in SoCal, I prefer white for it's use as a slow speed trail light and cornering light.
Another critical issue (and more important, IMO, than light color) is the location of the light itself. Because of their wide, flat pattern, fog lights are more functional when place as low as possible on a vehicle. They should be positioned as far apart as they can be, and be sitting low enough to be focused forward with a slight downward beam - this will provide the largest area of usable illumination, especially in low lying fog banks.
One final note: Fog lights are useless in Tule Fog, which is a phenomenon where the fog clouds literally touch the ground. As fog is water vapor, and light does not penetrate water vapor effectively, even fog lights won't help where there is no open space under the fog cloud. So, while fog lights can dramatically assist the driver in foul weather conditions, cornering / windy roads, and on slow trail driving, no light will do much for you if you get stuck in a Tule Fog situation - time to get out and walk !!!
Hope this helps you out...
