Mist was a kind of weather resembling fog. It could set in at night, making it more difficult to see. (COMIC: Unearthly Things [+]Loading...["Unearthly Things (comic story)"])
The Tenth Doctor was once heard to curse "for the mists of Clom." (PROSE: The Krillitane Storm [+]Loading...["The Krillitane Storm (novel)"])
The War Lords separated the various human armies on their test planet via barriers of mist. (TV: The War Games [+]Loading...["The War Games (TV story)"])