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Sastrugi
Sastrugi, or zastrugi, are features formed by the erosion of snow by wind. They are found in polar regions, and in snowy, wind-swept areas of temperate regions, such as frozen lakes or mountain ridges. Sastrugi are distinguished by upwind-facing points, resembling anvils, which move downwind as the surface erodes. These points usually lie along ridges parallel to the prevailing wind; they are steep on the windward side and sloping to the leeward side. Smaller irregularities of this type are known as ripples (small, ~10 mm high) or wind ridges. Large sastrugi are troublesome to skiers and snowboarders. Traveling on the irregular surface of sastrugi can be very tiring and can risk breaking equipment; ripples and waves are often undercut, and the surface is hard and unforgiving, with constant minor topographic changes between ridge and trough. Etymology The words ''sastrugi'' and ''zastrugi'' are Russian-language plurals; the singular is ''zastruga''. The form ''sastruga'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snow Or Ice Weather Phenomena
Snow consists of individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size, precipitate and accumulate on surfaces, then metamorphose in place, and ultimately melt, slide, or sublimate away. Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets, which freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles, columns, and rime. As snow accumulates into a snowpack, it may blow into drifts. Over time, accumulated snow metamorphoses, by sintering, sublimation, and freeze-thaw. Where the clima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barchan
A barchan or barkhan dune (from Kazakh бархан ) is a crescent-shaped dune. Russian naturalist Alexander von Middendorf introduced the term in 1881, working from the occurrence of barchans in Turkestan and in other inland desert regions. Barchans "face" the wind, appearing convex, and are produced by wind action predominantly from one direction. They are a very common landform in sandy deserts all over the world and are arc-shaped, markedly asymmetrical in cross section, with a gentle slope facing toward the wind sand ridge, comprising well-sorted sand. This type of dune possesses two "horns" that face downwind, with the steeper slope known as the slip face, facing away from the wind, downwind, at the angle of repose of the sand in question, approximately 30–35 degrees for medium-fine dry sand. The upwind side is packed by the wind, and stands at about 15 degrees. Barchans may be high and wide at the base measured perpendicular to the wind. Simple barchan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cornice (snow)
A snow cornice or simply cornice (from the Italian cornice meaning "ledge") is an overhanging edge of snow on a ridge or the crest of a mountain and along the sides of gullies. Formation A snow cornice forms by wind blowing snow over sharp terrain breaks (e.g. the crest of the mountain) where it attaches and builds out horizontally. This build-up is most common on the steeper and leeward sides of mountains. Cornices are extremely dangerous and travelling above or below them should be avoided. When a cornice ''collapses'', it breaks in from the cornice to the top of the peak; even being on the snow on top of rock exposes the alpinist to hazard in this situation. The best practice in mountaineering is to stay far enough back from the edge so as not to be able to see the drop, as an approximate metric of exposure. Interview und Bilder zum Unglück In avalanche safety, cornices are a high avalanche danger as they often break and trigger larger avalanches that permeate several snow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cape Sastrugi
The Deep Freeze Range () is a rugged mountain range, over long and about wide, rising between Priestley and Campbell Glaciers in Victoria Land, Antarctica, and extending from the edge of the polar plateau to Terra Nova Bay. It is southwest of the Southern Cross Mountains, south of the Mesa Range and northeast of the Eisenhower Range of the Prince Albert Mountains. Exploration and name Peaks in the low and mid portions of the range were observed by early British expeditions to the Ross Sea. The range was mapped in detail by the United States Geological Survey (USGS) from surveys and U.S. Navy air photos, 1955-63. It was named by the United States Advisory Committee on Antarctic Names (US-ACAN) in recognition of the support to research provided by the U.S. Navy's Operation Deep Freeze expeditions to Antarctica for many years beginning in 1954. Location The Deep Freeze Range extends from southeast to northwest, between Priestley Glacier and Campbell Glacier. The narrow nort ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Ice
Sea ice arises as seawater freezes. Because ice is less density, dense than water, it floats on the ocean's surface (as does fresh water ice). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the Arctic sea ice ecology and history, ocean's ecosystems. Due to the action of winds, currents and temperature fluctuations, sea ice is very dynamic, leading to a wide variety of ice types and features. Sea ice may be contrasted with icebergs, which are chunks of ice shelf, ice shelves or glaciers that Ice calving, calve into the ocean. Depending on location, sea ice expanses may also incorporate icebergs. General features and dynamics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dune
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes, with little or no vegetation, are called ''Erg (landform), ergs'' or ''sand seas''. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the wiktionary:stoss, stoss (upflow) side, where the sand is pushed up the dune, and have a shorter ''slip face'' in the lee side. The valley or trough between dunes is called a ''dune slack''. Dunes are most common in desert environments, where the lack of moisture hinders the growth of vegetation that would otherwise interfere with the development of dunes. However, sand deposits are not restricted to deserts, and dunes are also found along sea shores, along streams in semiarid climates, in areas of Outwash plain, glacial outwash ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aeolian Landforms
Aeolian commonly refers to things related to either of two Greek mythological figures: * Aeolus (son of Hippotes), ruler of the winds * Aeolus (son of Hellen), son of Hellen and eponym of the Aeolians * Aeolians, an ancient Greek tribe thought to be descended from Aeolus, son of Hellen Aeolian or Eolian may also refer to: Music * ''Aeolian'' (album), an album by German post-metal band The Ocean Collective * Aeolian Company (1887–1985), a maker of organs, pianos, sheet music, and phonographs * Aeolian Hall (other), any one of a number of concert halls of that name * Aeolian harp, a harp that is played by the wind * Aeolian mode, a musical mode, the natural minor key * Aeolian Quartet (1952–1981), a string quartet based in London * Aeolian-Skinner (1932–1972), pipe organ builder Other uses * Aeolian dialect, a dialect of Ancient Greek * Aeolian Islands, islands in the Tyrrhenian Sea, named after Aeolus the ruler of the winds * Aeolian or Aeolic order, an ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowdrift
A snowdrift is a deposit of snow sculpted by wind into a mound during a snowstorm. Snowdrifts resemble sand dunes and are formed in a similar manner, namely, by wind moving light snow and depositing it when the wind has virtually stopped, usually against a stationary object. Snow normally crests and slopes off toward the surface on the windward side of a large object. On the leeward side, areas near the object are a bit lower than surrounding areas but are generally flatter. The impact of snowdrifts on transportation can be more significant than the snowfall itself, such as in the US during the Great Blizzard of 1978. Snowdrifts are usually found at or on roads, as the crest of the roadbed or the Furrow (other), furrows along the road create the disruption to the wind needed to shed its carried snow. Snow fences may be employed on the windward side of the road to intentionally create a drift before the snow-laden wind reaches the road. Photo gallery File:Long Mynd s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Föhn Wind
A Foehn, or Föhn (, , , ), is a type of dry, relatively warm katabatic wind, downslope wind in the leeward, lee of a mountain range. It is a rain shadow wind that results from the subsequent adiabatic warming of air that has dropped most of its moisture on windward and leeward, windward slopes (see orographic lift). As a consequence of the different adiabatic lapse rates of moist and dry air, the air on the leeward slopes becomes warmer than equivalent elevations on the windward slopes. Foehn winds can raise atmospheric temperature, temperatures by as much as in just a matter of hours. Switzerland, southern Germany, and Austria have a warmer climate due to the Foehn, as moist winds off the Mediterranean Sea blow over the Alps. Etymology The name ''Foehn'' (, ) arose in the Alps, Alpine region. Originating from Latin , a mild west wind of which Zephyrus, Favonius was the Roman personification and probably transmitted by or just , the term was adopted as . In the Southern A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melt Ponds
Melt ponds are pools of open water that form on sea ice in the warmer months of spring and summer. The ponds are also found on glacial ice and ice shelves. Ponds of melted water can also develop under the ice, which may lead to the formation of thin underwater ice layers called false bottoms. Melt ponds are usually darker than the surrounding ice, and their distribution and size is highly variable. They absorb solar radiation rather than reflecting it as ice does and, thereby, have a significant influence on Earth's radiation balance. This differential, which had not been scientifically investigated until recently, has a large effect on the rate of ice melting and the extent of ice cover. Melt ponds can melt through to the ocean's surface. Seawater entering the pond increases the melt rate because the salty water of the ocean is warmer than the fresh water of the pond. The increase in salinity also depresses the water's freezing point. Water from melt ponds over land surfac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recrystallization (geology)
In geology, solid-state recrystallization is a metamorphic process that occurs under high temperatures and pressures where atoms of minerals are reorganized by diffusion and/or dislocation glide. During this process, the physical structure of the minerals is altered while the composition remains unchanged. This is in contrast to metasomatism, which is the chemical alteration of a rock by hydrothermal and other fluids. Solid-state recrystallization can be illustrated by observing how snow recrystallizes to ice. When snow is subjected to varying temperatures and pressures, individual snowflakes undergo a physical transformation but their composition remains the same. Limestone is a sedimentary rock that undergoes metamorphic recrystallization to form marble, and clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sublimation (phase Transition)
Sublimation is the Phase transition, transition of a substance directly from the solid to the gas state, without passing through the liquid state. The verb form of sublimation is ''sublime'', or less preferably, ''sublimate''. ''Sublimate'' also refers to the product obtained by sublimation. The point at which sublimation occurs rapidly (for further details, see #False correspondence with vaporization, below) is called critical sublimation point, or simply sublimation point. Notable examples include sublimation of dry ice at room temperature and atmospheric pressure, and that of solid iodine with heating. The reverse process of sublimation is deposition (phase transition), ''deposition'' (also called ''desublimation''), in which a substance passes directly from a gas to a solid phase, without passing through the liquid state. Technically, all solids may sublime, though most sublime at extremely low rates that are hardly detectable under usual conditions. At standard condi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
