"It's called 'black ice' because it tends to look like the rest of the pavement on the road, although in reality, it's actually clear," the US Forest Service notes. "Black ice forms without creating bubbles, which allows it to blend in with any surface it forms over. Black ice is dangerous precisely because it's hard to detect."

Black ice is an invisible cold weather danger, but how does it form and how can you protect yourself when walking and driving?

Black ice is a deadly driving hazard defined as patchy ice on roadways or other transportation surfaces that cannot easily be seen.