Probably a phenomenon you'll never see! Black ice is when water falls as rain but freezes onto the roadway in a way that just looks like the road is wet, not icy. It looks like wet pavement, but is ice, so traction is impossible, and because folks are expecting it, can be deadly when you try to do something like break suddenly. It'll throw you into a spin, and only practiced, experienced drivers can get out of that without crashing.