Hoar frost (or hoarfrost, sometimes simply frost) is the solid deposition of ice on the ground and on objects. It forms by direct deposition of water vapour into ice crystals. It should not be confounded with white dew which forms through condensation of vapour on cold objects and then freezing. Hoar frost forms directly when the dew point is below 0 °C. In this case, the water vapour pass immediately into hoar frost.