A thick subsurface layer of soil that remains frozen throughout the year, occurring chiefly in polar regions.
More example sentences
- The permafrost below the topsoil is frozen all year around, and this prevents roots from penetrating deeply into the ground.
- In regions influenced by permafrost, water migrates along the thermal gradient from warm to cold, thereby feeding ice in the frozen core.
- In many high mountains regions, permafrost may be present.