Ice fog

Ice fog is a type of fog consisting of fine ice crystals suspended in the air. It occurs only in cold areas of the world, as water droplets suspended in the air can remain liquid down to −40 °C (−40 °F). It should be distinguished from diamond dust, a precipitation of sparse ice crystals falling from a clear sky.

Ice fog is not the same thing as freezing fog, a phenomenon where the liquid water droplets making up the fog freezes to surfaces forming a rime.