Originally Posted by
cyccommute
You can still see it. It's not "invisible". Rime ice (the type that would form from water vapor freezing out of the air at 0°F) traps a lot of air in it and appears white. True "black" ice is appears as a wet surface because the surface is either wet or it is reflective or both.
Saying that you "were just driving along and hit a patch of black ice that I didn't see" is the motorist's equivalent of a JRA in bicycling.
Rime ice is different. You'll set it on chain link fences, trees, etc. I'll see it on my person too from my breath freezing. Black ice on streets from car exhaust doesn't look like that at all. Maybe it would if left to itself but it's getting constantly driven over.
You also have to remember that morning commutes in the winter often occur before sunrise or just after it. Lighting is low and uneven. There are shadows. The roads themselves typically have a grayish hue from salt residue and will be darker in some places and lighter in others. You can see black ice when your eyeballs are 6 inches away, but it's pretty easy not to recognize it as ice when further away.