How is the frost formed? A change of state.

The physical state of frosting changes as follows:

The state change involved in frost is sublimation. F. When the water vapor rises to high altitude and the temperature drops below 0℃, the water vapor condenses into small ice crystals, and the surrounding water vapor contacts with them, and crystallizes into snow in the falling process.

Frost is a phenomenon that water vapor (gaseous water) condenses when the temperature is very low. When the ground cools below 0℃ at night, the water vapor in the air condenses on the ground or the ice crystals on the ground are called frost. Outdoor in winter, the radiation of plants at night is slow, the ground temperature is particularly low, and the water vapor is not emitted quickly. When it gathers on the surface of plants, it freezes and forms frost.

Frost refers to white ice crystals that condense on the ground or objects when the air near the ground is cooled below the frost point (dew point is below 0) due to the radiation cooling of the ground. Frost is a weather phenomenon, which belongs to ground meteorological observation in China. "Frost" usually appears from autumn to spring. Meteorology generally refers to the early frost in autumn as "first frost" or "first frost", and the final frost in spring as "late frost" or "final frost". The interval from the last frost to the first frost is a frost-free period.

Scientifically speaking, frost is made up of ice crystals, similar to dew. When the relative humidity in the air reaches 100%, water is separated from the air. The only difference between them is that the dew point (the temperature at which water vapor liquefies into dew) is higher than the freezing point, while the frost point (the temperature at which water vapor condenses into frost) is lower than the freezing point, so frost will only appear when the near-surface temperature is lower than 0℃.