Parameter Tree:
EARTH SCIENCE > LAND SURFACE > FROZEN GROUND

Definition:
Soil within which the moisture has predominantly changed to ice, the unfrozen portion being in vapor phase.
Ice within the soil bonds adjacent soil particles and renders frozen ground very hard. Permanently frozen ground is called permafrost. Dry frozen ground is relatively loose and crumbly because of the lack of bonding
ice. Frozen ground is sometimes in-advisedly called frost or ground frost.


Reference:
American Meteorological Society Glossary of Meteorology Online http://amsglossary.allenpress.com/glossary