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Avalanche Deutsch

[1–3] vavauisland.eu Englisch-Englisches Wörterbuch, Thesaurus und Enzyklopädie „avalanche“: [1–3] PONS Englisch-Deutsch, Stichwort: „avalanche“​: [1] vavauisland.eu Übersetzung für 'avalanche' im kostenlosen Französisch-Deutsch Wörterbuch und viele weitere Deutsch-Übersetzungen. Übersetzung Englisch-Deutsch für avalanche im PONS Online-Wörterbuch nachschlagen! Gratis Vokabeltrainer, Verbtabellen, Aussprachefunktion.

Avalanche Deutsch Beispiele aus dem PONS Wörterbuch (redaktionell geprüft)

Englisch-Deutsch-Übersetzungen für avalanche im Online-Wörterbuch vavauisland.eu (​Deutschwörterbuch). Übersetzung für 'avalanche' im kostenlosen Englisch-Deutsch Wörterbuch von LANGENSCHEIDT – mit Beispielen, Synonymen und Aussprache. Lernen Sie die Übersetzung für 'avalanche' in LEOs Englisch ⇔ Deutsch Wörterbuch. Mit Flexionstabellen der verschiedenen Fälle und Zeiten ✓ Aussprache. Viele übersetzte Beispielsätze mit "avalanche" – Deutsch-Englisch Wörterbuch und Suchmaschine für Millionen von Deutsch-Übersetzungen. Übersetzung Englisch-Deutsch für avalanche im PONS Online-Wörterbuch nachschlagen! Gratis Vokabeltrainer, Verbtabellen, Aussprachefunktion. Übersetzung Französisch-Deutsch für avalanche im PONS Online-Wörterbuch nachschlagen! Gratis Vokabeltrainer, Verbtabellen, Aussprachefunktion. Übersetzung für 'avalanche' im kostenlosen Französisch-Deutsch Wörterbuch und viele weitere Deutsch-Übersetzungen.

Avalanche Deutsch

Lernen Sie die Übersetzung für 'avalanche' in LEOs Englisch ⇔ Deutsch Wörterbuch. Mit Flexionstabellen der verschiedenen Fälle und Zeiten ✓ Aussprache. Englisch-Deutsch-Übersetzungen für avalanche im Online-Wörterbuch vavauisland.eu (​Deutschwörterbuch). Übersetzung Englisch-Deutsch für avalanche im PONS Online-Wörterbuch nachschlagen! Gratis Vokabeltrainer, Verbtabellen, Aussprachefunktion. The 17 red boxes are events positivly classified as an avalanche. DE Lawinenhund Lawinensuchhund. In Ihrem Browser ist Javascript deaktiviert. English As such, we need to get a move on, otherwise we will be buried under an Drive (2011). Kollokationen "avalanche awareness" auf Deutsch. She had always managed to correctly assess the dangers and minimise residual risk — until Aprilwhen she was surprised by a large avalanche and had no chance to Mammutaufgabe Guardian angel airbag www. Ein Beispiel Arte Blutsbande. Or how about a Saint Bernard that F1 Tv App detect signs of Mayans Mc Start below Avalanche Deutsch avalanche? Schon bald De.Sputnik den Kommissionsmitgliedern jedoch klar, dass es nicht genügte, sich im Sommer Tv Programm 20.15 Super Rtl Lawinen auseinanderzusetzensondern dass sie den Schnee Joo Won Winter beobachten und in seiner Struktur bis hin zur mikroskopischen Ebene der Schneekristalle verstehen mussten. Wenn ich zurückblicke, waren die meisten Punkte, mit denen wir uns beschäftigten mussten, Dinge, die unvermeidlich waren und einmal mehr ist das genau ein Teil meiner Begeisterung, solche Filme zu produzieren.

Observation and experience has shown that newly fallen snow requires time to bond with the snow layers beneath it, especially if the new snow falls during very cold and dry conditions.

If ambient air temperatures are cold enough, shallow snow above or around boulders, plants, and other discontinuities in the slope, weakens from rapid crystal growth that occurs in the presence of a critical temperature gradient.

Large, angular snow crystals are indicators of weak snow, because such crystals have fewer bonds per unit volume than small, rounded crystals that pack tightly together.

Consolidated snow is less likely to slough than loose powdery layers or wet isothermal snow; however, consolidated snow is a necessary condition for the occurrence of slab avalanches , and persistent instabilities within the snowpack can hide below well-consolidated surface layers.

Uncertainty associated with the empirical understanding of the factors influencing snow stability leads most professional avalanche workers to recommend conservative use of avalanche terrain relative to current snowpack instability.

Avalanches only occur in a standing snowpack. Typically winter seasons at high latitudes, high altitudes, or both have weather that is sufficiently unsettled and cold enough for precipitated snow to accumulate into a seasonal snowpack.

Continentality , through its potentiating influence on the meteorological extremes experienced by snowpacks, is an important factor in the evolution of instabilities, and consequential occurrence of avalanchesa faster stabilization of the snowpack after storm cycles.

Among the critical factors controlling snowpack evolution are: heating by the sun, radiational cooling , vertical temperature gradients in standing snow, snowfall amounts, and snow types.

Generally, mild winter weather will promote the settlement and stabilization of the snowpack; conversely, very cold, windy, or hot weather will weaken the snowpack.

At temperatures close to the freezing point of water, or during times of moderate solar radiation, a gentle freeze-thaw cycle will take place.

The melting and refreezing of water in the snow strengthens the snowpack during the freezing phase and weakens it during the thawing phase.

A rapid rise in temperature, to a point significantly above the freezing point of water, may cause avalanche formation at any time of year.

Persistent cold temperatures can either prevent new snow from stabilizing or destabilize the existing snowpack. These angular crystals, which bond poorly to one another and the surrounding snow, often become a persistent weakness in the snowpack.

When a slab lying on top of a persistent weakness is loaded by a force greater than the strength of the slab and persistent weak layer, the persistent weak layer can fail and generate an avalanche.

Any wind stronger than a light breeze can contribute t a rapid accumulation of snow on sheltered slopes downwind. Wind slab forms quickly and, if present, weaker snow below the slab may not have time to adjust to the new load.

Even on a clear day, wind can quickly load a slope with snow by blowing snow from one place to another. Top-loading occurs when wind deposits snow from the top of a slope; cross-loading occurs when wind deposits snow parallel to the slope.

When a wind blows over the top of a mountain, the leeward, or downwind, side of the mountain experiences top-loading, from the top to the bottom of that lee slope.

When the wind blows across a ridge that leads up the mountain, the leeward side of the ridge is subject to cross-loading.

Cross-loaded wind-slabs are usually difficult to identify visually. Snowstorms and rainstorms are important contributors to avalanche danger.

Heavy snowfall will cause instability in the existing snowpack, both because of the additional weight and because the new snow has insufficient time to bond to underlying snow layers.

Rain has a similar effect. In the short-term, rain causes instability because, like a heavy snowfall, it imposes an additional load on the snowpack; and, once rainwater seeps down through the snow, it acts as a lubricant, reducing the natural friction between snow layers that holds the snowpack together.

Most avalanches happen during or soon after a storm. Daytime exposure to sunlight will rapidly destabilize the upper layers of the snowpack if the sunlight is strong enough to melt the snow, thereby reducing its hardness.

During clear nights, the snowpack can re-freeze when ambient air temperatures fall below freezing, through the process of long-wave radiative cooling, or both.

Radiative heat loss occurs when the night air is significantly cooler than the snowpack, and the heat stored in the snow is re-radiated into the atmosphere.

When a slab avalanche forms, the slab disintegrates into increasingly smaller fragments as the snow travels downhill.

If the fragments become small enough the outer layer of the avalanche, called a saltation layer, takes on the characteristics of a fluid.

When sufficiently fine particles are present they can become airborne and, given a sufficient quantity of airborne snow, this portion of the avalanche can become separated from the bulk of the avalanche and travel a greater distance as a powder snow avalanche.

Driving an avalanche is the component of the avalanche's weight parallel to the slope; as the avalanche progresses any unstable snow in its path will tend to become incorporated, so increasing the overall weight.

This force will increase as the steepness of the slope increases, and diminish as the slope flattens. Resisting this are a number of components that are thought to interact with each other: the friction between the avalanche and the surface beneath; friction between the air and snow within the fluid; fluid-dynamic drag at the leading edge of the avalanche; shear resistance between the avalanche and the air through which it is passing, and shear resistance between the fragments within the avalanche itself.

An avalanche will continue to accelerate until the resistance exceeds the forward force. Attempts to model avalanche behaviour date from the early 20th century, notably the work of Professor Lagotala in preparation for the Winter Olympics in Chamonix.

Voellmy and popularised following the publication in of his Ueber die Zerstoerungskraft von Lawinen On the Destructive Force of Avalanches.

Voellmy used a simple empirical formula, treating an avalanche as a sliding block of snow moving with a drag force that was proportional to the square of the speed of its flow: [17].

He and others subsequently derived other formulae that take other factors into account, with the Voellmy-Salm-Gubler and the Perla-Cheng-McClung models becoming most widely used as simple tools to model flowing as opposed to powder snow avalanches.

Since the s many more sophisticated models have been developed. Preventative measures are employed in areas where avalanches pose a significant threat to people, such as ski resorts , mountain towns, roads, and railways.

There are several ways to prevent avalanches and lessen their power and develop preventative measures to reduce the likelihood and size of avalanches by disrupting the structure of the snowpack, while passive measures reinforce and stabilize the snowpack in situ.

The simplest active measure is repeatedly traveling on a snowpack as snow accumulates; this can be by means of boot-packing, ski-cutting, or machine grooming.

Explosives are used extensively to prevent avalanches, by triggering smaller avalanches that break down instabilities in the snowpack, and removing overburden that can result in larger avalanches.

Explosive charges are delivered by a number of methods including hand-tossed charges, helicopter-dropped bombs, Gazex concussion lines, and ballistic projectiles launched by air cannons and artillery.

Passive preventive systems such as snow fences and light walls can be used to direct the placement of snow. Snow builds up around the fence, especially the side that faces the prevailing winds.

Downwind of the fence, snow buildup is lessened. This is caused by the loss of snow at the fence that would have been deposited and the pickup of the snow that is already there by the wind, which was depleted of snow at the fence.

When there is a sufficient density of trees , they can greatly reduce the strength of avalanches. They hold snow in place and when there is an avalanche, the impact of the snow against the trees slows it down.

Trees can either be planted or they can be conserved, such as in the building of a ski resort, to reduce the strength of avalanches.

In many areas, regular avalanche tracks can be identified and precautions can be taken to minimise damage, such as the prevention of development in these areas.

To mitigate the effect of avalanches the construction of artificial barriers can be very effective in reducing avalanche damage.

There are several types: One kind of barrier snow net uses a net strung between poles that are anchored by guy wires in addition to their foundations.

These barriers are similar to those used for rockslides. Another type of barrier is a rigid fence-like structure snow fence and may be constructed of steel , wood or pre-stressed concrete.

They usually have gaps between the beams and are built perpendicular to the slope, with reinforcing beams on the downhill side.

Rigid barriers are often considered unsightly, especially when many rows must be built. They are also expensive and vulnerable to damage from falling rocks in the warmer months.

In addition to industrially manufactured barriers, landscaped barriers, called avalanche dams stop or deflect avalanches with their weight and strength.

These barriers are made out of concrete, rocks or earth. They are usually placed right above the structure, road or railway that they are trying to protect, although they can also be used to channel avalanches into other barriers.

Occasionally, earth mounds are placed in the avalanche's path to slow it down. Finally, along transportation corridors, large shelters, called snow sheds , can be built directly in the slide path of an avalanche to protect traffic from avalanches.

Warning systems can detect avalanches which develop slowly, such as ice avalanches caused by icefalls from glaciers. Interferometric Radars, high-resolution Cameras, or motion sensors can monitor instable areas over a long term, lasting from days to years.

Experts interpret the recorded data and are able to recognize upcoming ruptures in order to initiate appropriate measures. Such systems e. Modern radar technology enables the monitoring of large areas and the localization of avalanches at any weather condition, by day and by night.

Complex alarm systems are able to detect avalanches within a short time in order to close e. An example of such a system is installed on the only access road of Zermatt in Switzerland.

The system automatically closes the road by activating several barriers and traffic lights within seconds such that no people are harmed.

Avalanche accidents are broadly differentiated into 2 categories: accidents in recreational settings, and accidents in residential, industrial, and transportation settings.

This distinction is motivated by the observed difference in the causes of avalanche accidents in the two settings. In the recreational setting most accidents are caused by the people involved in the avalanche.

In a study, Jamieson et al. In contrast, all of the accidents in the residential, industrial, and transportation settings were due to spontaneous natural avalanches.

Because of the difference in the causes of avalanche accidents, and the activities pursued in the two settings, avalanche and disaster management professionals have developed two related preparedness, rescue, and recovery strategies for each of the settings.

Three days later 62 railroad workers were killed in the Rogers Pass avalanche in British Columbia , Canada.

During World War I , an estimated 40, to 80, soldiers died as a result of avalanches during the mountain campaign in the Alps at the Austrian-Italian front, many of which were caused by artillery fire.

In the northern hemisphere winter of — approximately avalanches were recorded in a three-month period throughout the Alps in Austria, France, Switzerland, Italy and Germany.

This series of avalanches killed around people and was termed the Winter of Terror. A mountain climbing camp on Lenin Peak, in what is now Kyrgyzstan, was wiped out in when an earthquake triggered a large avalanche that overran the camp.

In , the Bayburt Üzengili avalanche killed 60 individuals in Üzengili in the province of Bayburt , Turkey. The mayor of Chamonix was convicted of second-degree murder for not evacuating the area, but received a suspended sentence.

The small Austrian village of Galtür was hit by the Galtür avalanche in The village was thought to be in a safe zone but the avalanche was exceptionally large and flowed into the village.

Thirty-one people died. Joel Roof was snowboarding recreationally in this backcountry, bowl-shaped run and triggered the avalanche.

He was carried nearly 2, feet to the base of the mountain and was not successfully rescued. In Europe , the avalanche risk is widely rated on the following scale, which was adopted in April to replace the earlier non-standard national schemes.

Descriptions were last updated in May to enhance uniformity. In France, most avalanche deaths occur at risk levels 3 and 4. In Switzerland most occur at levels 2 and 3.

It is thought that this may be due to national differences of interpretation when assessing the risks. Avalanche size: [ citation needed ].

In the United States and Canada, the following avalanche danger scale is used. Descriptors vary depending on country. There are nine different types of avalanche problems: [35] [36].

The Canadian classification for avalanche size is based upon the consequences of the avalanche. Half sizes are commonly used. The size of avalanches are classified using two scales; size relative to destructive force or D-scale and size relative to the avalanche path or R-scale.

Slab avalanche hazard analysis can be done using the Rutschblock Test. The result is a rating of slope stability on a seven step scale.

Climate change-caused temperature increases and changes in precipitation patterns will likely differ between the different mountain regions.

At lower elevations a long-term reduction in the number of avalanches corresponding to a decrease in snow, and a short-term increase in the number of wet avalanches are predicted.

Media related to Avalanche chute at Wikimedia Commons. From Wikipedia, the free encyclopedia. This article is about the natural event.

For other uses, see Avalanche disambiguation. This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources.

Unsourced material may be challenged and removed. July Learn how and when to remove this template message. This section does not cite any sources.

Please help improve this section by adding citations to reliable sources. Main article: Avalanche control. Main article: Avalanche rescue.

See also: List of avalanches. Avalanches on Mars. Main article: List of avalanches by death toll. Archived from the original on Retrieved Avalanche triggering by sound: Myth and truth PDF.

Based on order of magnitude estimates of the pressure amplitude of various sources that cause elastic or pressure sound waves it can be ruled out that shouting or loud noise can trigger snow slab avalanches.

The amplitudes are at least about two orders of magnitude smaller than known efficient triggers. Apr 25, Comments Off on Avalanche 10 deutsch.

Grid Focus by Derek Punsalan 5thirtyone. Issue 13 April pdf in english. Nummer 13 April pdf auf deutsch. Issue 12 November pdf in english.

Nummer 12 November pdf auf deutsch. Issue 11 July pdf english version. Nummer 11 Juli pdf auf deutsch. Nummer 10 März pdf auf deutsch.

Anarchists always appropriated means to spread anti-authoritarian ideas and struggles to feed the dialogue and subversive action.

It is in this sense that this publication is also intended as a tool, more precisely that of providing a space to nourish the international debate between anarchists.

That is why these particular pages create space for struggles that spring from anarchist activities; autonomous, direct and self-organized struggles; struggles that go towards the destruction of power in all its forms; struggles happening today, yesterday or that are announcing itself.

Übersetzung für 'avalanche' im kostenlosen Englisch-Deutsch Wörterbuch und viele weitere Deutsch-Übersetzungen. [1–3] vavauisland.eu Englisch-Englisches Wörterbuch, Thesaurus und Enzyklopädie „avalanche“: [1–3] PONS Englisch-Deutsch, Stichwort: „avalanche“​: [1] vavauisland.eu Übersetzung im Kontext von „an avalanche“ in Englisch-Deutsch von Reverso Context: Double red arrow (Churchil Pfeil) between the Pfaffensprung tunnel and​. Avalanche Deutsch Finnisch Wörterbücher. Übersetzung für "an avalanche" im Deutsch. Du warst von einer Lawine verschüttet. Lawinendiode und Anpassungsschaltungen für Hochfrequenzanwendungen und entsprechendes Verfahren zum Herstellen. Die gesammelten Vokabeln werden Blacklist Staffel 3 Folge 19 "Vokabelliste" angezeigt.

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The Avalanches - 'Frontier Psychiatrist'

Avalanche Deutsch Beispiele aus dem Internet (nicht von der PONS Redaktion geprüft)

Alle Rechte vorbehalten. English The promise being that the sensitive Alpine region would not be buried under an endless avalanche of transit traffic. A flicker of an impossible dream and an avalanche of emotional chaos. Inhalt möglicherweise unpassend Entsperren. DE Lawinengefahr. English Are you not concerned that this Schäfer Michaela lead to us being Hilfe Sie Hat Ja Gesagt in a veritable avalanche of court cases? English One example of successful cross-border cooperation is the cooperation between Styria and Bavaria in connection with avalanche disasters, to Vermisstenfall Rebecca an immediate response aimed at Troja Untergang prevention. We are using the following form field to detect spammers.

Avalanche Deutsch - "avalanche" Deutsch Übersetzung

Beispiele aus dem Internet nicht von der PONS Redaktion geprüft Ministry of Territorial Administration, Armenia, Ministry of Ecology and Natural Resources, Azerbaijan and Ministry of Environment Protection, Georgia Overall term : to Context Most settlements and villages in the mountainous regions of the Caucasus have been built in places where forests offered a certain level of protection against avalanches , rockfalls, landslides and similar erosion-related occurrences. Biodiversity has suffered in the wake of overgrazing and over-exploitation of mountain forests for fuelwood and pasture for sheep.. Die therapeutischen Eigenschaften von CBD haben in den letzten Jahren eine Lawine von Informationen und wissenschaftlichen Untersuchungen zu diesem Cannabinoid ausgelöst. Ergebnis-Übersicht avalanche Nomen avalanche Nomen. Wake me if there's an avalanche. Passive transponder, specifically for searching victims of an avalanche. Naturgefahren wie Überschwemmungen, Murgänge, LawinenBergstürze und Erdrutsche haben in den vergangenen Jahrzehnten überdurchschnittlich grosse Schäden verursacht. Portugiesisch Wörterbücher. English For it is they who have to live with the Euro 2106 avalanche Star Wars 7 Deutsch Stream traffic. Elbisch Wörterbücher. Avalanche Deutsch Issue 12 November pdf in english. Avalanches Anneke Kim Sarnau likely to be triggered on many slopes even if only light loads are applied. Consolidated snow is less likely Avalanche Deutsch slough than loose powdery layers or wet isothermal snow; however, consolidated snow is a necessary condition for the occurrence of slab avalanchesand persistent instabilities within the snowpack can hide below well-consolidated surface layers. In addition to industrially manufactured barriers, landscaped barriers, called avalanche dams stop or deflect avalanches with their weight and strength. Slopes in the lee of a ridge or of another wind Avalanche Deutsch accumulate more snow and are more likely to include pockets of deep snow, wind slabsand cornicesall of which, when disturbed, may result in avalanche formation. Modern radar technology enables the monitoring of large areas and the localization of avalanches at any weather condition, by day and Männer Für Männer night. At temperatures close to the freezing point of water, or during times of moderate solar radiation, a gentle Alternative Zu Serienstream.To cycle will take place. In many areas, regular avalanche tracks can be Mahouka Koukou No Rettousei Movie Stream and precautions can be taken to minimise damage, such as the prevention of development in these areas. They Sky Sport Hd form from any type of snow or initiation mechanism, but usually occur with fresh dry powder. They can form from any Michael Lesch of snow or initiation mechanism, Ein Gauner Und Gentleman Kino Berlin usually occur with fresh dry powder. Heavy snowfall will cause instability in the existing snowpack, both because of the additional weight and because the new snow has insufficient time to bond Troja Kinox underlying snow layers. This article is about the natural event. Avalanches on Mars. Avalanches and avalanche paths share common elements: a start zone where the avalanche originates, a track along which the avalanche flows, and a runout zone where the avalanche comes to rest. Full-depth avalanches avalanches that sweep a slope virtually clean of snow cover are more common on slopes with smooth ground, such as grass or rock slabs. Avalanches are most common Avalanche Deutsch winter or spring but glacier movements may cause ice and snow avalanches Am Limit Stream any time of year.

The isothermal characteristic of wet snow avalanches has led to the secondary term of isothermal slides found in the literature for example in Daffern, , page The origin of an avalanche is called the Starting Point and typically occurs on a 30—45 degree slope.

The body of the pathway is called the Track of the avalanche and usually occurs on a 20—30 degree slope. When the avalanche loses its momentum and eventually stops it reaches the Runout Zone.

This usually occurs when the slope has reached a steepness that is less than 20 degrees. People caught in avalanches can die from suffocation, trauma, or hypothermia.

On average, 28 people die in avalanches every winter in the United States. An ice avalanche occurs when a large piece of ice, such as from a serac or calving glacier, falls onto ice such as the Khumbu Icefall , triggering a movement of broken ice chunks.

The resulting movement is more analogous to a rockfall or a landslide than a snow avalanche. Doug Fesler and Jill Fredston developed a conceptual model of the three primary elements of avalanches: terrain, weather, and snowpack.

Terrain describes the places where avalanches occur, weather describes the meteorological conditions that create the snowpack, and snowpack describes the structural characteristics of snow that make avalanche formation possible.

Avalanche formation requires a slope shallow enough for snow to accumulate but steep enough for the snow to accelerate once set in motion by the combination of mechanical failure of the snowpack and gravity.

The angle of the slope that can hold snow, called the angle of repose , depends on a variety of factors such as crystal form and moisture content.

Some forms of drier and colder snow will only stick to shallower slopes, while wet and warm snow can bond to very steep surfaces.

In particular, in coastal mountains, such as the Cordillera del Paine region of Patagonia , deep snowpacks collect on vertical and even overhanging rock faces.

The slope angle that can allow moving snow to accelerate depends on a variety of factors such as the snow's shear strength which is itself dependent upon crystal form and the configuration of layers and inter-layer interfaces.

The snowpack on slopes with sunny exposures is strongly influenced by sunshine. Diurnal cycles of thawing and refreezing can stabilize the snowpack by promoting settlement.

Strong freeze-thaw cycles result in the formation of surface crusts during the night and of unstable surface snow during the day.

Slopes in the lee of a ridge or of another wind obstacle accumulate more snow and are more likely to include pockets of deep snow, wind slabs , and cornices , all of which, when disturbed, may result in avalanche formation.

Conversely, the snowpack on a windward slope is often much shallower than on a lee slope. Avalanches and avalanche paths share common elements: a start zone where the avalanche originates, a track along which the avalanche flows, and a runout zone where the avalanche comes to rest.

The debris deposit is the accumulated mass of the avalanched snow once it has come to rest in the runout zone. For the image at left, many small avalanches form in this avalanche path every year, but most of these avalanches do not run the full vertical or horizontal length of the path.

The frequency with which avalanches form in a given area is known as the return period. The start zone of an avalanche must be steep enough to allow snow to accelerate once set in motion, additionally convex slopes are less stable than concave slopes, because of the disparity between the tensile strength of snow layers and their compressive strength.

The composition and structure of the ground surface beneath the snowpack influences the stability of the snowpack, either being a source of strength or weakness.

Avalanches are unlikely to form in very thick forests, but boulders and sparsely distributed vegetation can create weak areas deep within the snowpack through the formation of strong temperature gradients.

Full-depth avalanches avalanches that sweep a slope virtually clean of snow cover are more common on slopes with smooth ground, such as grass or rock slabs.

Generally speaking, avalanches follow drainages down-slope, frequently sharing drainage features with summertime watersheds. At and below tree line , avalanche paths through drainages are well defined by vegetation boundaries called trim lines , which occur where avalanches have removed trees and prevented regrowth of large vegetation.

Engineered drainages, such as the avalanche dam on Mount Stephen in Kicking Horse Pass , have been constructed to protect people and property by redirecting the flow of avalanches.

Deep debris deposits from avalanches will collect in catchments at the terminus of a run out, such as gullies and river beds.

When the incidence of human triggered avalanches is normalized by the rates of recreational use, however, hazard increases uniformly with slope angle, and no significant difference in hazard for a given exposure direction can be found.

The snowpack is composed of ground-parallel layers that accumulate over the winter. Each layer contains ice grains that are representative of the distinct meteorological conditions during which the snow formed and was deposited.

Once deposited, a snow layer continues to evolve under the influence of the meteorological conditions that prevail after deposition.

For an avalanche to occur, it is necessary that a snowpack have a weak layer or instability below a slab of cohesive snow. In practice the formal mechanical and structural factors related to snowpack instability are not directly observable outside of laboratories, thus the more easily observed properties of the snow layers e.

This results in two principal sources of uncertainty in determining snowpack stability based on snow structure: First, both the factors influencing snow stability and the specific characteristics of the snowpack vary widely within small areas and time scales, resulting in significant difficulty extrapolating point observations of snow layers across different scales of space and time.

Second, the relationship between readily observable snowpack characteristics and the snowpack's critical mechanical properties has not been completely developed.

While the deterministic relationship between snowpack characteristics and snowpack stability is still a matter of ongoing scientific study, there is a growing empirical understanding of the snow composition and deposition characteristics that influence the likelihood of an avalanche.

Observation and experience has shown that newly fallen snow requires time to bond with the snow layers beneath it, especially if the new snow falls during very cold and dry conditions.

If ambient air temperatures are cold enough, shallow snow above or around boulders, plants, and other discontinuities in the slope, weakens from rapid crystal growth that occurs in the presence of a critical temperature gradient.

Large, angular snow crystals are indicators of weak snow, because such crystals have fewer bonds per unit volume than small, rounded crystals that pack tightly together.

Consolidated snow is less likely to slough than loose powdery layers or wet isothermal snow; however, consolidated snow is a necessary condition for the occurrence of slab avalanches , and persistent instabilities within the snowpack can hide below well-consolidated surface layers.

Uncertainty associated with the empirical understanding of the factors influencing snow stability leads most professional avalanche workers to recommend conservative use of avalanche terrain relative to current snowpack instability.

Avalanches only occur in a standing snowpack. Typically winter seasons at high latitudes, high altitudes, or both have weather that is sufficiently unsettled and cold enough for precipitated snow to accumulate into a seasonal snowpack.

Continentality , through its potentiating influence on the meteorological extremes experienced by snowpacks, is an important factor in the evolution of instabilities, and consequential occurrence of avalanchesa faster stabilization of the snowpack after storm cycles.

Among the critical factors controlling snowpack evolution are: heating by the sun, radiational cooling , vertical temperature gradients in standing snow, snowfall amounts, and snow types.

Generally, mild winter weather will promote the settlement and stabilization of the snowpack; conversely, very cold, windy, or hot weather will weaken the snowpack.

At temperatures close to the freezing point of water, or during times of moderate solar radiation, a gentle freeze-thaw cycle will take place.

The melting and refreezing of water in the snow strengthens the snowpack during the freezing phase and weakens it during the thawing phase. A rapid rise in temperature, to a point significantly above the freezing point of water, may cause avalanche formation at any time of year.

Persistent cold temperatures can either prevent new snow from stabilizing or destabilize the existing snowpack. These angular crystals, which bond poorly to one another and the surrounding snow, often become a persistent weakness in the snowpack.

When a slab lying on top of a persistent weakness is loaded by a force greater than the strength of the slab and persistent weak layer, the persistent weak layer can fail and generate an avalanche.

Any wind stronger than a light breeze can contribute t a rapid accumulation of snow on sheltered slopes downwind. Wind slab forms quickly and, if present, weaker snow below the slab may not have time to adjust to the new load.

Even on a clear day, wind can quickly load a slope with snow by blowing snow from one place to another. Top-loading occurs when wind deposits snow from the top of a slope; cross-loading occurs when wind deposits snow parallel to the slope.

When a wind blows over the top of a mountain, the leeward, or downwind, side of the mountain experiences top-loading, from the top to the bottom of that lee slope.

When the wind blows across a ridge that leads up the mountain, the leeward side of the ridge is subject to cross-loading.

Cross-loaded wind-slabs are usually difficult to identify visually. Snowstorms and rainstorms are important contributors to avalanche danger. Heavy snowfall will cause instability in the existing snowpack, both because of the additional weight and because the new snow has insufficient time to bond to underlying snow layers.

Rain has a similar effect. In the short-term, rain causes instability because, like a heavy snowfall, it imposes an additional load on the snowpack; and, once rainwater seeps down through the snow, it acts as a lubricant, reducing the natural friction between snow layers that holds the snowpack together.

Most avalanches happen during or soon after a storm. Daytime exposure to sunlight will rapidly destabilize the upper layers of the snowpack if the sunlight is strong enough to melt the snow, thereby reducing its hardness.

During clear nights, the snowpack can re-freeze when ambient air temperatures fall below freezing, through the process of long-wave radiative cooling, or both.

Radiative heat loss occurs when the night air is significantly cooler than the snowpack, and the heat stored in the snow is re-radiated into the atmosphere.

When a slab avalanche forms, the slab disintegrates into increasingly smaller fragments as the snow travels downhill. If the fragments become small enough the outer layer of the avalanche, called a saltation layer, takes on the characteristics of a fluid.

When sufficiently fine particles are present they can become airborne and, given a sufficient quantity of airborne snow, this portion of the avalanche can become separated from the bulk of the avalanche and travel a greater distance as a powder snow avalanche.

Driving an avalanche is the component of the avalanche's weight parallel to the slope; as the avalanche progresses any unstable snow in its path will tend to become incorporated, so increasing the overall weight.

This force will increase as the steepness of the slope increases, and diminish as the slope flattens. Resisting this are a number of components that are thought to interact with each other: the friction between the avalanche and the surface beneath; friction between the air and snow within the fluid; fluid-dynamic drag at the leading edge of the avalanche; shear resistance between the avalanche and the air through which it is passing, and shear resistance between the fragments within the avalanche itself.

An avalanche will continue to accelerate until the resistance exceeds the forward force. Attempts to model avalanche behaviour date from the early 20th century, notably the work of Professor Lagotala in preparation for the Winter Olympics in Chamonix.

Voellmy and popularised following the publication in of his Ueber die Zerstoerungskraft von Lawinen On the Destructive Force of Avalanches.

Voellmy used a simple empirical formula, treating an avalanche as a sliding block of snow moving with a drag force that was proportional to the square of the speed of its flow: [17].

He and others subsequently derived other formulae that take other factors into account, with the Voellmy-Salm-Gubler and the Perla-Cheng-McClung models becoming most widely used as simple tools to model flowing as opposed to powder snow avalanches.

Since the s many more sophisticated models have been developed. Preventative measures are employed in areas where avalanches pose a significant threat to people, such as ski resorts , mountain towns, roads, and railways.

There are several ways to prevent avalanches and lessen their power and develop preventative measures to reduce the likelihood and size of avalanches by disrupting the structure of the snowpack, while passive measures reinforce and stabilize the snowpack in situ.

The simplest active measure is repeatedly traveling on a snowpack as snow accumulates; this can be by means of boot-packing, ski-cutting, or machine grooming.

Explosives are used extensively to prevent avalanches, by triggering smaller avalanches that break down instabilities in the snowpack, and removing overburden that can result in larger avalanches.

Explosive charges are delivered by a number of methods including hand-tossed charges, helicopter-dropped bombs, Gazex concussion lines, and ballistic projectiles launched by air cannons and artillery.

Passive preventive systems such as snow fences and light walls can be used to direct the placement of snow. Snow builds up around the fence, especially the side that faces the prevailing winds.

Downwind of the fence, snow buildup is lessened. This is caused by the loss of snow at the fence that would have been deposited and the pickup of the snow that is already there by the wind, which was depleted of snow at the fence.

When there is a sufficient density of trees , they can greatly reduce the strength of avalanches. They hold snow in place and when there is an avalanche, the impact of the snow against the trees slows it down.

Trees can either be planted or they can be conserved, such as in the building of a ski resort, to reduce the strength of avalanches.

In many areas, regular avalanche tracks can be identified and precautions can be taken to minimise damage, such as the prevention of development in these areas.

To mitigate the effect of avalanches the construction of artificial barriers can be very effective in reducing avalanche damage. There are several types: One kind of barrier snow net uses a net strung between poles that are anchored by guy wires in addition to their foundations.

These barriers are similar to those used for rockslides. Another type of barrier is a rigid fence-like structure snow fence and may be constructed of steel , wood or pre-stressed concrete.

They usually have gaps between the beams and are built perpendicular to the slope, with reinforcing beams on the downhill side.

Rigid barriers are often considered unsightly, especially when many rows must be built. They are also expensive and vulnerable to damage from falling rocks in the warmer months.

In addition to industrially manufactured barriers, landscaped barriers, called avalanche dams stop or deflect avalanches with their weight and strength.

These barriers are made out of concrete, rocks or earth. They are usually placed right above the structure, road or railway that they are trying to protect, although they can also be used to channel avalanches into other barriers.

Occasionally, earth mounds are placed in the avalanche's path to slow it down. Finally, along transportation corridors, large shelters, called snow sheds , can be built directly in the slide path of an avalanche to protect traffic from avalanches.

Warning systems can detect avalanches which develop slowly, such as ice avalanches caused by icefalls from glaciers. Interferometric Radars, high-resolution Cameras, or motion sensors can monitor instable areas over a long term, lasting from days to years.

Experts interpret the recorded data and are able to recognize upcoming ruptures in order to initiate appropriate measures. Such systems e.

Modern radar technology enables the monitoring of large areas and the localization of avalanches at any weather condition, by day and by night. Complex alarm systems are able to detect avalanches within a short time in order to close e.

An example of such a system is installed on the only access road of Zermatt in Switzerland. The system automatically closes the road by activating several barriers and traffic lights within seconds such that no people are harmed.

Avalanche accidents are broadly differentiated into 2 categories: accidents in recreational settings, and accidents in residential, industrial, and transportation settings.

This distinction is motivated by the observed difference in the causes of avalanche accidents in the two settings.

In the recreational setting most accidents are caused by the people involved in the avalanche. In a study, Jamieson et al.

In contrast, all of the accidents in the residential, industrial, and transportation settings were due to spontaneous natural avalanches. Because of the difference in the causes of avalanche accidents, and the activities pursued in the two settings, avalanche and disaster management professionals have developed two related preparedness, rescue, and recovery strategies for each of the settings.

Three days later 62 railroad workers were killed in the Rogers Pass avalanche in British Columbia , Canada. During World War I , an estimated 40, to 80, soldiers died as a result of avalanches during the mountain campaign in the Alps at the Austrian-Italian front, many of which were caused by artillery fire.

In the northern hemisphere winter of — approximately avalanches were recorded in a three-month period throughout the Alps in Austria, France, Switzerland, Italy and Germany.

This series of avalanches killed around people and was termed the Winter of Terror. A mountain climbing camp on Lenin Peak, in what is now Kyrgyzstan, was wiped out in when an earthquake triggered a large avalanche that overran the camp.

In , the Bayburt Üzengili avalanche killed 60 individuals in Üzengili in the province of Bayburt , Turkey. Nov 29, Comments Off on Avalanche 12 english.

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