We've seen the signs, but we've never actually seen it happen from above.

A video from high above Flint shows the phenomenon that we've all heard of but never seen - it's the Lapeer St. bridge over I-69, frozen over while the roads surrounding it are not. We even made the news in my hometown of Milwaukee for it.

The signs are all over the highway, but seeing it from the sky really puts it in perspective. Why does it happen, you might ask? It's just science.

Bill Nye GIF

Bridges basically exist in mid-air, so the cold air hits them from all sides. The roads are heated by the soil underneath them, so their surfaces warm faster. Bridges have no way of trapping heat, so they freeze faster.

A friendly reminder to heed those signs when you see them, because bridges really DO freeze before the road.

More From Cars 108