rime Q Rime like hoar and white frost is a term for what is technically known as hoarfrost , a thin but visible, white sheet of ice crystals. Rime forms on a surface that is at a temperature below freezing when water droplets, typically of fog or mist, fall to the surface from air that is cold enough that the droplets, when they land, are frozen or so nearly frozen that they freeze before they can spread out as liquid. Rime is visible because air pockets in the frozen water droplets make the droplets appear white. In contrast with rime, black_ice is ice in a thin, clear and practically invisible sheet. Black ice, which is the technical term, forms on a surface that is at a temperature below freezing when water droplets fall to the surface through air that is warm enough that the droplets are not frozen or nearly frozen before landing and so on contacting the surface form a thin liquid layer before freezing occurs. Rime is about as slippery as ordinary ice, but it is not very hazardousness because it can be seen. In contrast black ice, which is ordinary ice and so as slippery as such, is extremely hazardous on streets, sidewalks, steps, and the like because it cannot be seen. 041219 what's it to you? who go blather from