Cryosphere Glossary

albedo

a measure of the reflectivity of a surface ranging from 0 to 1; albedo is calculated by taking the ratio of reflected radiation to incoming radiation, such that a surface that reflects 100% of light hitting it has an albedo of 1, and a surface that absorbs 100% of the light hitting it has an albedo of 0.

anomaly

irregularity or deviation from normal.

anthropogenic

of, relating to, or resulting from the influence of human beings on nature.

brine

water with a high salt content.

cryosphere

the set of all locations on or beneath Earth's surface where frozen water exists.

fast ice

ice that is anchored to the shore or ocean bottom, typically over shallow ocean shelves at continental margins; fast ice is defined by the fact that it does not move with the winds or currents.

feedback

exchange between the input and the output of a system.

first-year ice

floating ice of no more than one year's growth developing from young ice; thickness ranges from 0.3 to 2 meters (1 to 6.6 feet); first-year ice is characteristically level (flat) where it is undisturbed by pressure, but can be rough and angular where ridges occur.

glacier

a mass of ice that originates on land, usually having an area larger than one tenth of a square kilometer; many believe that a glacier must show some type of movement; others believe that a glacier can show evidence of past or present movement.

greenhouse gas

any gas, including carbon dioxide, water vapor, ozone and methane, that traps heat in the Earth's atmosphere.

iceberg

a piece of ice that has broken off from the end of a glacier that ends in water.

ice sheet

a dome-shaped mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometers (12 million acres) (e.g., the Greenland and Antarctic ice sheets).

ice shelf

portion of an ice sheet that spreads out over water.

land ice

any part of Earth's ice cover that formed over land primarily from freezing precipitation, as opposed to sea ice formed by the freezing of seawater.

multiyear ice

ice that has survived at least one melt season; it is typically 2 to 4 meters (6.6 to 13.1 feet) thick and thickens as more ice grows on its underside.

new ice

a general category of ice representing the earliest stages of sea ice growth.

permafrost

layer of soil or rock, at some depth beneath the surface, in which the temperature has been continuously below 0°C for at least several years; it exists where summer heating fails to reach the base of the layer of frozen ground.

salinity

measurement of salt content.

sea ice

any form of ice found at sea which formed from the freezing of sea water.

sea ice concentration

the fraction of an area that is covered by sea ice.

sea ice extent

the total area covered by some amount of ice, including open water between ice floes; sea ice extent is typically measured in square kilometers.

thermodynamic equilibrium

the state of a system in which its energy distribution is such that all parts of the system have the same temperature and no heat flows.

thermodynamics

the study of conversions between heat and other forms of energy.

thermohaline circulation

deep-ocean currents driven by differences in the water's density, which is controlled by temperature (thermo) and salinity (haline).

young ice

a general category of ice that is less than one year old and about 10 to 30 centimeters (4 to 12 inches) thick.