A listener mentioned that she earlier this winter she had ice on her driveway after storm. In the morning, the pavement was dry, but the temperature never got above freezing and she hadn’t used any chemicals to melt the ice. She wanted to know “Where did the ice go?” A possible answer is sublimation. That is when a substance goes directly from a solid state to a vapor state – by passing the liquid form. The ice turned to water vapor, without melting. In physical and chemical literature, it is common to consider only the transition from solid to vapor, but not in the meteorological world. You sometimes see frost formation directly from water vapor, rather than condensation that freezes. This is known as deposition, and is commonly referred to as hoarfrost, which we have discussed in earlier stories.
Mary Knapp, Weather Data Library