Frost Forms Directly From Vapour, Skipping Water
Frost is a coating of ice crystals. It does not come from frozen dew: water vapour turns straight to ice without becoming liquid.
Frost is a thin coating of ice crystals on a cold surface. It is not frozen dew: when a surface is below freezing, water vapour in the air turns straight into ice without passing through the liquid stage, a process called *deposition*. That is why frost forms feathery crystal shapes rather than frozen droplets. A *frosty reception* uses the same coldness figuratively, and *frosting* is the American word for icing on a cake.
- Ice crystals on a surface. *A hard frost.*
- Freezing weather. *Frost is forecast.*
- Frosty — cold, or unfriendly. *A frosty reception.*
- Frostbite — tissue damage from cold. *Frostbite in the fingers.*
- Frosting — cake icing, American. *Chocolate frosting.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | frost | Heavy frost. |
| Verb | frost | The window frosted. |
| Adjective | frosty | A frosty morning. |
| Compound | frostbite | Frostbite. |
| Old English | forst | Frost. |
- There was frost on the grass.Weather.
- He got a frosty reception.Figurative.
- Vapour turns straight to ice.Physics.
Kinds of frost
- Hoar frost — feathery white crystals from deposition
- Ground frost — the surface freezes though the air stays above zero
- Air frost — the air temperature itself drops below freezing
- Rime — ice from freezing fog droplets, not deposition
- Black ice — frozen liquid water, not frost at all
Old English *forst* or *frost*, from a Germanic root related to *freeze*, shared with German *Frost*.
Is frost just frozen dew?
No. Frost forms when vapour turns directly to ice on a surface below freezing, skipping the liquid stage entirely.
What is the difference between ground frost and air frost?
Ground frost means the surface is below freezing; air frost means the air temperature itself is.