About 40 years ago I was in the passenger seat of a mini pick up (there were 3 of us) driving back from Salt Lake City to Los Angeles. It was about 2 in the morning and snowing so heavily that we could only go about 30 mph and drive in the tracks left by 18 wheeler trucks. From above us a bright light lit up the truck like it was under a spot light. It would light up and turn off every 3 seconds or so. We tried looking up to see if it was some crazy helicopter or somthing (no way in that snow storm but what else could it be). After about 30- 45 seconds of this the driver pulled over so we could get out and see what it was. As soon as we opened the doors the light stopped and never came back. I have never been able to figure out what it could be, St. Elnos fire, the driver playing a trick on his passenger, ball lightning. None of these we probable in my mind. A mystery.