Cryosphere glossary
either of the two points of intersection of the sun's apparent annual path and the plane of the earth's equator; in the northern hemisphere the spring (vernal) equinox falls on or about 21 March, and the autumnal equinox on or about 22 September.
the difference between a measured value of a quantity and its true value; different types of errors are inherent to observations.
a sinuous ridge of sedimentary material (typically gravel or sand) deposited by streams that cut channels under or through the glacier ice.
the physical process by which a liquid or solid substance is transformed to the gaseous state; the opposite of condensation; in meteorology, evaporation usually is restricted in use to the change of water from liquid to gas, while sublimation is used to the change from solid to gas as well as from gas to solid.
the volume of ice in the ground which exceeds the total pore volume that the ground would have under natural unfrozen conditions.
(1) (North American usage) permafrost underlying 65 - 90% of the area of exposed land surface (2) (Russian usage) permafrost underlying 70 - 80% of the area of exposed land surface.