Frostpoint temperature T f is the temperature at which the water vapour contained in a gas starts to form frost when cooled

霜点温度是气体中包含的 水蒸汽开始结霜时的温度 or 或者

Frostpoint is defined as the temperature at which a moist gas is saturated with respect to a plane surface of pure ice

霜点是湿气体达到饱和 状态并在平面表面产生纯冰时的温度