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frost




hoarfrost
Frozen atmospheric moisture formed on objects when the temperature is below 0°C, the freezing point. Hoarfrost forms in roughly the same way as dew but, owing to the low temperature, the water vapor sublimes (see sublimation) from gaseous to solid state to form ice crystals on the surface. The delicate patterns often seen on windows is hoarfrost. Glazed frost usually forms when rain falls on an object below freezing: it can be seen, for example, on telegraph wires. Rime occurs when supercooled when water droplets contact a surface that is also below 0°C; it may result from fog or drizzle. The first frost of the season signifies the end of the growing season.


Related category

   • ATMOSPHERIC PHENOMENA AND STRUCTURES