It was super foggy this morning, some of the thickest I've ever seen. I just happened to come across a cyclist (extremely rare around here) while driving my car, just after a 4-way stop sign intersection on a 55-MPH highway crossing a 45-MPH rural road. Since I was still relatively slow from turning at the intersection, I had plenty of time to react to him. He had a light on the rear, but it was very dim and not flashing. I couldn't make out the light at all until I was very close.

A combination of BRIGHT steady and flashing lights are really important in fog as thick as it was today.