What condition is necessary for the formation of ice fog?

Ice fog typically forms under specific atmospheric conditions where water vapor can condense and freeze into tiny ice crystals suspended in the air. The necessary condition for this phenomenon to occur is a temperature below freezing. When the air temperature drops significantly, it allows the moisture in the air to freeze, leading to the creation of ice fog.

In many instances, ice fog is observed in polar regions or during extremely cold temperatures, where high humidity combined with low temperatures results in the formation of these ice crystals. While high humidity, low wind speeds, and clear skies can contribute to the presence of ice fog, they are not essential in the same way that sub-zero temperatures are. Thus, the defining factor for ice fog to develop is the presence of temperatures below the freezing point.