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Subglacial Channel
A subglacial meltwater channel is a channel beneath an ice mass, such as ice sheets and valley glaciers, roughly parallel to the main ice flow direction. These meltwater channels can have different sizes, ranging from very small channels of a metre deep and wide to big valleys which can be up to a kilometre wide. The dimensions of these channels are regulated by several factors: water temperature, meltwater volume, debris content in the water, ice wall closure rates (governed by the ice thickness) and squeezing of fluidized sediment. In the glaciological literature three forms of subglacial meltwater channels are commonly mentioned. R-channels The first type of channel is the ''R-channel'' after Hans Röthlisberger who initiated work on water pressures in tubes under glaciers. These are semi-circular channels cut upward into the ice. The balance between channel enlargement by viscous heating and closure by ice deformation when the channels are water-filled reflects their size and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Sheet
In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at Last Glacial Maximum, the Laurentide Ice Sheet covered much of North America, the Weichselian ice sheet covered Northern Europe and the Patagonian Ice Sheet covered southern South America. Ice sheets are bigger than ice shelves or alpine glaciers. Masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery. Although the surface is cold, the base of an ice sheet is generally warmer due to geothermal heat. In places, melting occurs and the melt-water lubricates the ice sheet so that it flows more rapidly. This process produces fast-flowing channels in the ice sheet — these are ice streams. The present-day polar ice sheets are relatively young in geol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valley Glacier
A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over a very long period. Some valleys are formed through erosion by glacial ice. These glaciers may remain present in valleys in high mountains or polar areas. At lower latitudes and altitudes, these glacially formed valleys may have been created or enlarged during ice ages but now are ice-free and occupied by streams or rivers. In desert areas, valleys may be entirely dry or carry a watercourse only rarely. In areas of limestone bedrock, dry valleys may also result from drainage now taking place underground rather than at the surface. Rift valleys arise principally from earth movements, rather than erosion. Many different types of valleys are described by geographers, using terms that may be global in use or else applied only locally. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glaciology
Glaciology (; ) is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice. Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. The impact of glaciers on people includes the fields of human geography and anthropology. The discoveries of water ice on the Moon, Mars, Europa and Pluto add an extraterrestrial component to the field, which is referred to as "astroglaciology". Overview A glacier is an extended mass of ice formed from snow falling and accumulating over a long period of time; glaciers move very slowly, either descending from high mountains, as in valley glaciers, or moving outward from centers of accumulation, as in continental glaciers. Areas of study within glaciology include glacial history and the reconstruction of past glaciation. A glaciologist is a person who studies glaciers. A glacial geologist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Röthlisberger
Hans Röthlisberger (1 February 1923 – 10 September 2009) was a Swiss earth scientist and glaciologist best known for his work on glacier hazards and their prevention, glacier geophysics and subglacial hydrology. Hans (his given name) was born on February 1, 1923 in Langnau, Canton Bern, Switzerland. After completing formal education as a teacher training in Bern he began studies in the earth sciences at ETH Zürich (ETHZ) in 1943, where he earned his diploma in 1947. Röthlisberger then embarked on a PhD on the topic of seismic investigations of molasse rocks, under the guidance of Professor Dr. F. Gassmann at the Geophysical Institute of ETH Zürich. His interest in glaciers was fostered by his mountaineering activities, and while working on his PhD, Hans Röthlisberger participated in scientific expeditions in eastern Greenland (1951; EGIG, Expédition Glaciologique Internationale au Groenland) and on Baffin Island (1950 and 1953), where he performed seismic geophysical exper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and even by industry. Further, both spellings are often used ''within'' a particular industry or country. Industries in British English-speaking countries typically use the "gauge" spelling. is the pressure relative to the ambient pressure. Various units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the SI unit of pressure, the pascal (Pa), for example, is one newton per square metre (N/m2); similarly, the pound-force per square inch (psi) is the traditional unit of pressure in the imperial and U.S. customary systems. Pressure may also be expressed in terms of standard atmospheric pressure; the atmosphere (atm) is equal to this pressure, and the torr is defined as of this. Manometric uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Pressure
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 760mm Hg, 29.9212 inchesHg, or 14.696psi.International Civil Aviation Organization. ''Manual of the ICAO Standard Atmosphere'', Doc 7488-CD, Third Edition, 1993. . The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, the Earth's atmospheric pressure at sea level is approximately 1 atm. In most circumstances, atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so atmospheric pressure decreases with increasing elevation. Because the atmosphere is thin relative to the Earth's radius—especially the dense atmospheric layer at low altitudes—the Earth's gravi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Nye (scientist)
John Frederick Nye (26 February 1923 – 8 January 2019) was a British physicist and glaciologist. He was the first to apply plasticity to understand glacier flow.'EC%2F1976%2F26'&dsqDb=Catalog" target="_blank" class="mw-redirect" title="Certificates of Election and Candidature, RefNo EC/1976/26: Nye, John Frederick">Certificates of Election and Candidature, RefNo EC/1976/26: Nye, John Frederick . Accessed 2009-04-26. Career His early work was on the of plasticity, spanning ice |
