(1) There is a folk proverb in China: "It is cold before frost and cold after snow." It explained that the frost was caused by _ _ _ _ _ _ _ _ _ _ _ _ _.

(1) When the weather is particularly col

(1) There is a folk proverb in China: "It is cold before frost and cold after snow." It explained that the frost was caused by _ _ _ _ _ _ _ _ _ _ _ _ _.

(1) When the weather is particularly cold, the water vapor in the air will directly turn into solid small ice crystals and attach to the ground to form frost, which belongs to sublimation; When the temperature rises, snow will change from solid to liquid, and the melting process will occur. It needs to absorb heat when it melts, so it will feel cold.

(2) In winter, the temperature in the classroom is high and the temperature outside the classroom is low. When the water vapor in the classroom is cold (low temperature glass), it liquefies into small water droplets and adheres to the inner surface of the glass.

So the answer is: (1) low; Ninghua; Suck; (2) internal; liquefy