Last winter, the foggy weather in Hefei was more frequent than in previous years, but the frost was less. From the analysis of the change of material state, the formation of "frost" belongs to _ _ _ _

Last winter, the foggy weather in Hefei was more frequent than in previous years, but the frost was less. From the analysis of the change of material state, the formation of "frost" belongs to _ _ _ _ _ _ phenomenon; Frost is a solid, which is formed by the heat release of water vapor in the air and belongs to sublimation phenomenon; Sprinkling salt in ice and snow can make the ice and snow melt quickly, because the melting point of ice decreases after adding salt, and the ice and snow can melt below 0℃.

So, the answer is: Ninghua; Release; Reduce the melting point of snow.