Cryosphere glossary
little ice age
a period of cooling that started around the early 14th century, peaked in the 17th century, and ended in the mid-19th century, and was marked by expanding glaciers in Europe, North America, and Asia
long-term strength
the failure strength of a material after a long period of creep deformation.
longwave radiation
heat radiation with wavelengths greater than 4 millimeters.
low
area of low pressure in the atmosphere.
low-center polygon
an ice-wedge polygon in which thawing of ice-rich permafrost has left the central area in a relatively depressed position.
low-level clouds
clouds in the lower region of the atmosphere, from ground level to 6500 feet (2000 meters); includes stratus, stratocumulus, the bases of cumulus and cumulonimbus, and sometimes nimbostratus clouds.
luminous pillars
white or sometimes reddish vertical streaks of light extending from above and below the sun; they are caused by light reflected off the mirror-like surfaces of ice; most commonly seen at sunrise and sunset.
macro-scale polygons
closed, multi-sided, roughly equidimensional, patterned ground features, typically 15 to 30 meters (16 to 33 yards) across; commonly resulting from thermal contraction cracking of the ground.
magnetic pole
either of the two points on the earth's surface at which magnetic meridians converge; the horizontal component of the magnetic field of the earth becomes zero at this point; also called the dip pole.
marginal crevasse
a crevasse near the side of a glacier formed as the glacier moves past stationary valley walls; usually oriented about 45 degrees up-glacier from the side wall.
marginal ice zone
a part of the seasonal ice zone that varies in width (100 to 200 kilometers, 62 to 124 miles) that extends from the ice edge into the ice pack, where waves and swells affect the ice; often characterized by highly variable ice conditions; in general, it is wider in the Antarctic than the Arctic.
Image
A scenic view within the marginal ice zone.
marine climate
a climate dominated by the ocean; because of the moderating effect of water, sites having this climate are considered relatively mild.
marine cryopeg
a layer or body of unfrozen ground, that is perennially cryotic (T < 0 degrees Celsius), forming part of the coastal or subsea permafrost.
maritime
of, relating to, or adjacent to the sea.
mass balance
the difference between accumulation and ablation on a glacier; usually calculated on an annual basis.
mass wasting
downslope movement of soil or rock on, or near, the earth's surface under the influence of gravity.
massive cryostructure
the cryostructure of frozen sand in which all mineral particles are bonded together with ice.
massive ice
a comprehensive term used to describe large masses of ground ice, including ice wedges, pingo ice, buried ice and large ice lenses.
massive-agglomerate cryostructure
the cryostructure of frozen silt or loam in which ice veins form an irregular three-dimensional network.
massive-porous cryostructure
the cryostructure of frozen sand and gravel in which all mineral particles are bonded together with ice, but larger pore spaces are not completely filled with ice.