a general term for floating ice which has been squeezed together and in places forced upwards; includes rafted ice, telescoped ice, hummocked ice and ridge ice.
process that occurs when wind, ocean currents, and other forces push sea ice around into piles that rise and form small mountains above the level sea ice surface; ridges are initially thin and transparent with very sharp edges from blocks of ice piling up; also see keels.
the meridian (line of longitude) defined to be 0 degrees and passing through the Royal Greenwich Observatory in London; also known as the International Meridian or Greenwich Meridian; the Prime Meridian and the opposite 180th meridian (at 180 degrees longitude) separate the Eastern and Western Hemispheres.
pseudomorph
in geology, a mineral compound resulting from a process by which the primary mineral component is replaced by another, although the compound maintains constant appearance and dimensions.
an instrument used for measuring the water vapor content of the atmosphere; a type of hygrometer; it consists of two thermometers, one of which (the dry bulb) is an ordinary glass thermometer, while the other (wet bulb) has its bulb covered with a jacket of clean muslin which is saturated with distilled water prior to an observation; when the bulbs are suitably ventilated, they indicate the thermodynamic wet- and dry-bulb temperatures of the atmosphere; one variety is the assman psychrometer (a special form of aspiration psychrometer for which the ventilation is provided by a suction fan).
an accumulation of melt water on an ice surface, mainly due to melting snow, but in later stages also to the melting of ice; the initial stage consists of patches of slush.
The Columbia Glacier surged (advanced rapidly) earlier this century, part of it flowing into a forest. The push moraine in this photograph from 1914 shows Columbia Glacier literally pushing up trees and dirt as it advanced. (Photo courtesy of D.K. Handy, archived at the World Data Center for Glaciology, Boulder, CO.)
(1) emission or transfer of energy in the form of electromagnetic waves (2) the process by which electromagnetic radiation is propagated through free space by virtue of joint undulatory variations in the electric and magnetic fields in space; this concept is to be distinguished from conduction and convection.
instrument intended to be carried by a balloon up through the atmosphere, equipped with sensors to measure one or several meteorological variables (pressure, temperature, humidity, etc.), and provided with a radio transmitter for sending this information to the observing station.
a glacier that is reconstructed or reconstituted out of other glacier material; usually formed by seracs falling from a hanging glacier then re-adhering; also called reconstituted glacier, regenerated glacier, or glacier remainie.
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regelation
motion of an object through ice by melting and freezing that is caused by pressure differences; this process allows a glacier to slide past small obstacles on its bed.
a glacier that is reconstructed or reconstituted out of other glacier material; usually formed by seracs falling from a hanging glacier then re-adhering; also called reconstituted or reconstructed glacier, or glacier remainie.
The ratio of the absolute error in a measurement to the size of the measurement.
relative humidity
the (dimensionless) ratio of the actual vapor pressure of the air to the saturation vapor pressure; usually expressed as a percent, and can be computed from psychrometric data.
a layer of ground, now perennially frozen, lying immediately below the modern active layer; its thickness indicates the greater annual depth of thaw that occurred during a previous period.