Cryosphere glossary
tributary glacier
a small glacier that flows into a larger glacier.
Tropic of Cancer
the northern parallel of maximum solar declination, approximately 23° 27′ N latitude; the farthest northern latitude at which the sun can appear directly overhead, which occurs on the day of the summer solstice.
Tropic of Capricorn
the southern parallel of maximum solar declination, approximately 23° 27′ S latitude; the farthest southern latitude at which the sun can appear directly overhead, which occurs on the day of the summer solstice.
tropopause
the boundary layer between the troposphere and stratosphere, where an abrupt change in temperature lapse rate usually occurs; it is defined as the lowest level at which the lapse rate decreases to 2 degrees Celsius per kilometer or less, provided that the average lapse rate between this level and all higher levels within 2 kilometers does not exceed 2 degrees Celsius per kilometer; occasionally, a second tropopause may be found if the lapse rate above the first tropopause exceeds 3 degrees Celsius per kilometer.
troposphere
lower part of the atmosphere, extending from the surface up to a height varying from about 7 to 9 kilometers (4.3 to 5.6 miles) at polar regions to approximately 17 kilometers (10.6 miles) in tropics; characterized by decreasing temperature with height, appreciable vertical wind motion, appreciable water vapor content, and weather.
trough
in meteorology, an elongated area of relatively low atmospheric pressure; the opposite of a ridge.
tundra
treeless terrain, with a continuous cover of vegetation, found at both high latitudes and high altitudes.
turbic cryosol
a mineral soil showing marked evidence of cryoturbation, as indicated by broken horizons and displaced material.
turf hummock
a hummock consisting of vegetation and organic matter with or without a core of mineral soil or stones.
turf-banked (solifluction) lobe
a solifluction lobe with its front covered by a vegetation mat.
turf-banked (solifluction) terrace
a solifluction terrace with its front covered by a vegetation mat.
two-layer permafrost
ground in which two layers of permafrost are separated by a layer of unfrozen ground.
two-phase thermosyphon
a passive heat transfer device, filled with a temperature-dependent liquid/vapour combination, installed to remove heat from the ground.