Cryosphere glossary
gradient wind
the same as geostrophic wind, but blowing parallel to curved isobars or contours; the curved airflow pattern around a pressure center results from a balance among pressure-gradient force, coriolis force, and centrifugal force.
granic cryogenic fabric
a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete loosely packed units.
granoidic cryogenic fabric
a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form more or less discrete loosely packed units.
graupel
snowflakes that become rounded pellets due to riming; typical sizes are 2 to 5 millimeters in diameter (0.1 to 0.2 inch); graupel is sometimes mistaken for hail.
gravimetric (total) water content
the ratio of the mass of the water and ice in a sample to the dry mass of the sample, commonly expressed as a percentage.
gravity wave
a wave disturbance in which buoyancy (or reduced gravity) acts as a restoring force on parcels displaced from hydrostatic equilibrium; there is a direct oscillatory conversion between potential and kinetic energy in the wave motion.
gravity wind
a cold wind blowing down an incline; a kind of katabatic wind.
grease ice
a very thin, soupy layer of frazil crystals clumped together, which makes the ocean surface resemble an oil slick.
Image
Grease ice (thin, light-grey area) with thick ice floes.
Ted Maksym, United States Naval Academy
Greenland high
the anticyclone that appears to overlie Greenland; analogous to the antarctic anticyclone.
grey-white ice
a category of young ice 15 to 30 centimeters (6 to 12 inches) thick, named for its color.
Image
Thin grey-white ice showing the effects of ridging and rafting.
Antarctic Sea-Ice Processes and Climate program (ASPeCt)
grid
a finite collection of points to which the meteorological variables used in a numerical model, or interpolated from observations, apply; a field of such regular values (points) is termed gridded field.
ground ice
a general term referring to all types of ice contained in freezing and frozen ground.
ground moraine
continuous layer of till near the edge or underneath a steadily retreating glacier.
growler
an iceberg less than 2 meters (6.6 feet) across that floats with less than 1 meter (3.3 feet) showing above water; smaller than a bergy bit.
hail
precipitation of small balls or pieces of ice (hailstones) with a diameter ranging from 5 to 50 millimeters (0.2 to 2.0 inches), or sometimes bigger, falling either separately or agglomerated into irregular lumps; when the diameter is less than about 5 millimeters (0.2 inch), the balls are called ice pellets.
halo
group of optical phenomena, in the form of rings, arcs, pillars or bright spots around the sun or moon, produced by the refraction or reflection of light by ice crystals suspended in the atmosphere (cirrus clouds, diamond dust, etc.).
hanging glacier
a glacier that terminates at or near the top of a cliff.
Image
Mt. Kefton, Antarctica
hanging valley
a valley formed by a small glacier that has a valley bottom relatively higher than nearby valleys formed by larger glaciers.
hard frozen ground
frozen ground (soil or rock) which is firmly cemented by ice.
haze
fine dust or salt particles dispersed through a portion of the atmosphere; the particles are so small that they cannot be felt or individually seen with the naked eye, but they diminish horizontal visibility and give the atmosphere a characteristic opalescent appearance that subdues all colors; a type of lithometeor.