Temperature, below 0º C (32º F), at which moisture in the air will condense as a layer of frost on any exposed surface. The frost point is analogous to the dew point, the temperature at which the water condenses in liquid form; both the frost point and the dew point depend upon the relative humidity of the air
When the temperature to which air must be cooled to in order to be saturated is below freezing.
Is the unique temperature to which the air (or any gas) must be cooled in order that it shall be saturated with respect to ice. ( 060)
Dew point below freezing.
the highest temperature at which atmospheric moisture will sublimate in the form of hoarfrost on a cooled surface; it is analogous to the dew point.