European's used to use a lot of yellow headlights in order to reduce glare in urban settings and for fog. At one time, all the NATO equipment in Germany and France was running yellow lights (1950's-60's). I remember that a lot of the civilain French cars in the '70's ran yellow headlights as well...
Currently I believe that they are relying a lot on the "city light" that is the offcenter small bulb installed in the light housings along with the H4 burners (familliar to those of you who have looked into doing a Hella E-Code H4 conversion who have noticed two different part numbers, one with, one without, the "city light"). You get enough light for folks to see you comming, and to highlight stuff right in front of you, but not to light up the road-they work well if you have a lot of overhead lighting such as that found in an urban environment and the H4 when lit up (in either low or high beam) really lights up in a rural area with the low beams having such a sharp cutoff that the glare situation is reduced considerably compared to the older lens design...
Now, does anyone (maybee David Doyle?) have any of the official paperwork from DOD concerning yellow lights?
I spotted a M35 a few months ago near me that was for sale (truck had been caught in a forest fire and was bassically destroyed except for the headlights and a few body panels) that had yellow lights. First time for that I had seen them personally in CONUS).
Turning the scoop around for reduction of ingested water (frozen or not) makes a lot of sense to me...
I'd hate to have to wait on a convoy stop to get heat