Ground frost

[1] Rime (both soft and hard) is technically not a type of ground frost.

Ground frost may also refer to the condition when the temperature of the upper layer of the soil falls below the freezing point of water.

[1] From 1906 to 1960 the Met Office practice was to base the number of days of ground frost on this criterion: a day with a minimum temperature reaching 30 °F (−1 °C), probably because 32 °F (0 °C) was not considered enough cold to cause damage to growing plants.

Since 1961 the statistics have referred to the number of days with grass minimum temperature below 0°C.

Occasionally, the term ground frost can still be seen, but it means simply a minimum temperature below 0 °C.

Ground frost in the highest town in Venezuela , Apartaderos ( Mérida state ). Because its location in an alpine tundra ecosystem called páramo , they often undergo a sudden and drastic change in a daily freeze-and-thaw cycle, sometimes described as "summer every day and winter every night."
Typical ground frost damage in asphalt