Freezing fog If fog is what happens when a cloud touches the ground, then what's freezing fog? You guessed it, freezing fog is fog that occurs when it's freezing or below freezing, and that means moisture on roadways can freeze, too, according to AccuWeather. That's a real hazard in cold-weather climates. You could be looking at icy spots on bridges and overpasses, and even black ice (another cold phenomenon we'll talk about ahead). Be careful out there! Have you ever seen freezing fog?

Frost flower Contrary to the name, a frost flower isn't exactly a flower. It's a cold phenomenon formed in freezing weather as the water in plant stems begins to expand as it freezes. This can cause vertical splits to form. The water leaving these splits freezes on contact with the frigid air, producing the flower-like structure you see here. The length of the split determines if the frost flower will be a narrow or wide ribbon, according to the NWS. Have you seen this beautiful phenomena?

Graupel sounds like something out of Grimms' Fairy Tales, but it's an actual winter-weather term meaning soft hail or pellets of snow. Merriam-Webster says the first mention of graupel comes from a 1889 weather report, and the name itself comes from the Germanic word graupe, which means "pearl barley." Have you seen it?

Black ice Contrary to its name, black ice isn't actually black. It's a sheet of thin, transparent ice found on pavement. It's notoriously difficult to see when driving or even when walking on the street, as the ice appears the same dark color as the roads.