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Glaciology is an interdisciplinary earth science that integrates geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. The impact of glaciers on humans adds the fields of human geography and anthropology. The presence of ice on Mars and Europa brings in an extraterrestrial component to the field.
Zones of glaciers
· Accumulation, where the formation of ice is faster than its removal.
· Wastage or Ablation, where the sum of melting and evaporation (sublimation) is greater than the amount of snow added each year.
Movement
Ablation
wastage of the glacier through sublimation, ice melting and iceberg calving.
Ablation zone
Area of a glacier in which the annual loss of ice through ablation exceeds the annual gain from precipitation.
Arête
an acute ridge of rock where two cirques abut.
Bergshrund
crevasse formed near the head of a glacier, where the mass of ice has rotated, sheared and torn itself apart in the manner of a geological fault.
Cirque, corrie or cwm
bowl shaped depression excavated by the source of a glacier.
Creep
adjustment to stress at a molecular level.
Flow
movement (of ice) in a constant direction.
Fracture
brittle failure (breaking of ice) under the stress raised when movement is too rapid to be accommodated by creep. It happens for example, as the central part of a glacier movinges faster than the edges.
Horn
spire of rock formed by the headward erosion of a ring of cirques around a single mountain. It is an extreme case of an arête.
Plucking/Quarrying
where the adhesion of the ice to the rock is stronger than the cohesion of the rock, part of the rock leaves with the flowing ice.
Tarn
a lake formed in the bottom of a cirque when its glacier has melted.
Tunnel valley
The tunnel is that formed by hydraulic erosion of ice and rock below an ice sheet margin. The tunnel valley is what remains of it in the underlying rock when the ice sheet has melted.
Sunday, May 30, 2010
snow pillow
A snow pillow is a device for measuring snowpack, especially for automated reporting stations such as SNOTEL.
The snow pillow measures the water equivalent of the snow pack based on hydrostatic pressure created by overlying snow. Any discrepancy due to bridging is minimized by the large dimension of the pillow, typically 3 metres (120 in) square.
Another application for snow pillows is to estimate the snow weight on a roof to warn of potential for roof collapse.
Snow pillows were developed in the early 1960s.
tropical cyclone
Storm surge
The main storm surge forecast model in the Atlantic basin is SLOSH, which stands for Sea, Lake, Overland, Surge from Hurricanes.[11] It uses the size of a storm, its intensity, its forward motion, and the topography of the coastal plain to estimate the depth of a storm surge at any individual grid point across the United States. An accurate forecast track is required in order to produce accurate storm surge forecasts. However, if the landfall point is uncertain, a maximum envelope of water (MEOW) map can be generated based on the direction of approach. If the forecast track itself is also uncertain, a maximum of maximums (MoM) map can be generated which will show the worst possible scenario for a hurricane of a specific strength.
Tornado
The location of most tropical cyclone-related tornadoes is their northeast quadrant in the Northern Hemisphere and southeast quadrant in the Southern Hemisphere.[13] Like most of the other forecasts for tropical cyclone effects, an accurate track forecast is required in order to produce an accurate tornado threat forecast.
Seasonal forecast
By looking at annual variations in various climate parameters, forecasters can make predictions about the overall number and intensity of tropical cyclones that will occur in a given season. For example, when constructing its seasonal outlooks, the Climate Prediction Center in the United States considers the effects of the El Niño-Southern Oscillation, 25-40 year tropical cycle, wind shear over the oceans, and ocean surface temperature.
The main storm surge forecast model in the Atlantic basin is SLOSH, which stands for Sea, Lake, Overland, Surge from Hurricanes.[11] It uses the size of a storm, its intensity, its forward motion, and the topography of the coastal plain to estimate the depth of a storm surge at any individual grid point across the United States. An accurate forecast track is required in order to produce accurate storm surge forecasts. However, if the landfall point is uncertain, a maximum envelope of water (MEOW) map can be generated based on the direction of approach. If the forecast track itself is also uncertain, a maximum of maximums (MoM) map can be generated which will show the worst possible scenario for a hurricane of a specific strength.
Tornado
The location of most tropical cyclone-related tornadoes is their northeast quadrant in the Northern Hemisphere and southeast quadrant in the Southern Hemisphere.[13] Like most of the other forecasts for tropical cyclone effects, an accurate track forecast is required in order to produce an accurate tornado threat forecast.
Seasonal forecast
By looking at annual variations in various climate parameters, forecasters can make predictions about the overall number and intensity of tropical cyclones that will occur in a given season. For example, when constructing its seasonal outlooks, the Climate Prediction Center in the United States considers the effects of the El Niño-Southern Oscillation, 25-40 year tropical cycle, wind shear over the oceans, and ocean surface temperature.
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