Avalanche is what? The causes and consequences of avalanches

Tiger in the skin of a lamb called innocent, at first glance, white snow Mathias Zdarsky - an Austrian researcher who was studying the question of what is an avalanche. Softly falling snow fascinates even those who do not like winter - too beautiful picture, like a fairy tale. And the crystal stars, smoothly flying to the ground, create a deceptive impression of fragility, defenseless tenderness. However, overly active snowfalls are fraught with danger, and not serious. In fact from small snowflakes can grow not only drifts, but also avalanches. So, what is an avalanche? The definition of this concept is given below. And now a little history.

A short excursion into the history

In all likelihood, the avalanche is a phenomenon that exists as much as the steep slopes of the mountains, and the first large snow convergence that caused the death of hundreds of people, also mentions Polybius in the context of the history of the Carthaginian army's trek through the Alps. And in general, this mountain massif, chosen by tourists and climbers, "behind the shoulders" is the longest chronicle of catastrophes. Not for nothing that in the twentieth century in certain regions mass in memory of those killed under snowy debris served, because in this case the avalanche is a pain and sorrow for the relatives and friends of those who suffered from its collapse. It is also remarkable that in one of the last winters of the First World War, this natural phenomenon killed more soldiers on the Austro-Italian front than it did directly during the hostilities. And on December 16, 1916 went down in history as "black Thursday", when six thousand people failed to count for one day. Hemingway, who was in the Alps in the same time interval and described his definition of what an avalanche means, noted that the winter landslides are terrible, sudden and carry instant death.

Suffered from the "white death" and the inhabitants of Norway, Iceland, Bulgaria, the United States, the Russian Federation, Canada, as well as Asian countries: Turkey, Nepal, Iran, Afghanistan, and in the latter, and the records of the dead are largely not maintained. Tens of thousands of lives and on the account of avalanches, which fell from Mount Huaskaran in Peru.

What is an avalanche? Etymology of the word

The ancient Romans called this phenomenon a "pile of snow." Each nation had its own definition. What does it mean - an avalanche? This is a beautiful, exciting and dangerous natural phenomenon. Interestingly, the very meaning of the word "avalanche", in the origins of which the Latin root lab, meaning "instability", although in Russian it came through German, because in ancient German there was a definition of Lavine. Buddhist monk Xuan Zang poetically called them "white dragons", and in the days of Pushkin, avalanches were called landslides. In the Alps and the Caucasus, the "speaking" are already the names of individual mountains, gorges and valleys. For example, the Lansky Forest or Zeygalan Hoch ("a mountain with which avalanches always go away"). Sometimes the ability to read onomastics, though it does not tell you everything about the snow blockages, can save you from unforeseen circumstances.

What is an avalanche

Avalanche is one of the types of landslides, a significant mass of snow that moves or even falls from the slopes of mountains under the influence of gravity. It creates an air wave in parallel, which accounts for a significant part of the damage and damage that is almost inevitable in this disaster.

Having started its movement, the avalanche can no longer stop, sinking lower and grabbing accompanying stones, ice blocks, branches and roots torn from the roots, turning from an ebullient white snow into a dirty mass remotely resembling a village. Its "fascinating journey" flow can continue until it stops on the flat sections or at the bottom of the valley.

Factors affecting the convergence of snow masses from the mountains

The reasons for avalanche convergence depend largely on the old snow - its height and density, the state of the surface beneath it, and the increase in new masses of precipitation. Also affects the intensity of snowfalls, subsidence and compaction of the cover and air temperature. In addition, a fairly long open slope (100-500 m) is optimal for starting the avalanche path.

The main "architect" of this natural phenomenon is not in vain called the wind, since for the convergence of snow there is enough growth of 10-15 cm. Temperature is also one of the most important factors that can provoke a catastrophe. And if at zero degrees, the instability of snow, although it appears quickly, but also passes through not less actively (it either melts, or the avalanche departs). And when the low temperature is stable, the avalanche period increases.

Activating the convergence of snow can also seismic fluctuations, which is not uncommon for the mountainous terrain. In some cases, enough and flights of jet aircraft over dangerous areas.

In general, frequent avalanches are indirectly or directly related to the rapid economic activity of a person, which is not always reasonable. For example, today's forested massifs used to be a natural protection against snow landslides.

Periodicity

Depending on the frequency of occurrence, one can distinguish between intra-annual convergence (during the winter and spring periods) and an average annual one, which includes, respectively, the total frequency of avalanche formation. Also, there are systematic avalanches (annually or every 2-3 years) and sporadic, occurring at most twice in a century, which makes them especially unpredictable.

Movement, focus of natural phenomenon

The nature of the motion of snow masses and the structure of the source determine the following classification: trough snow avalanches, special and jumping. In the case of the first, snow moves either along the tray or through a certain channel. Special avalanches during the movement cover the entire accessible area of the terrain. But with jumpers already interesting - they are reborn from the troughs, arising in places of uneven flow. The snow mass has to "jump", overcome certain areas. The latter type is able to develop the fastest speed, therefore, and the danger is very significant.

The snow is insidious and can crawl imperceptibly and inaudibly, collapsing with an unexpected shock wave, destroying everything in its path. The features of the motion of these natural masses underlie another division into types. In it stands a formation avalanche - this is when the movement occurs with respect to the surface of the snow located below, and also the ground one - it slips directly along the ground.

Scale

Depending on the damage caused, the avalanche is divided into especially dangerous (they are spontaneous) - the amount of material losses affects the imagination by its scale, and just dangerous - hinder the activities of various organizations and endanger the peaceful measured life of settlements.

Properties of snow

It is important to note the classification associated with the properties of the snow itself, which is the basis of the avalanche. Isolate dry, wet and damp. For the first, a high convergence rate and a powerful destructive air wave are characteristic, and the masses themselves are formed at sufficiently low temperatures after considerable snowfall. A wet avalanche is snow, which it would be desirable to leave cozy slopes at a temperature above zero. Speed of movement here is less, than at previous, however also the density of a cover is more. In addition, the base can be frozen, turning into a hard and dangerous layer. For wet avalanches the raw material is snow viscous, wet, and the mass of each cubic meter is of the order of 400-600 kg, and the speed of movement is 10-20 m / sec.

Volumes

Well and the most simple division - small and almost harmless, average and dangerous for the person, and also big which on the way erase from the face of the earth of a structure, trees, turn in a heap of scrap metal transport.

Is it possible to predict the occurrence of avalanches?

It is extremely difficult to predict avalanche convergence with a high degree of probability, since snow is an element of nature, which, by and large, is almost unpredictable. Of course, there are maps of dangerous areas and both passive and active methods are being taken to prevent this phenomenon. However, the causes and consequences of avalanches can be different and very palpable. Passive methods include special shield shields, forest tracts, points of observation for dangerous areas. Active actions consist in bombardment of sites of possible collapses from artillery and mortar installations, to provoke the convergence of snow masses in small batches.

Slithering from the mountains snow avalanches in any of the options represent a natural disaster. It does not matter whether they are small or big. It is extremely important to take into account all the factors that influence the occurrence of snow masses and their movement along an undefined route to unknown targets, so as not to sacrifice too expensive gifts for the elements.

All about avalanches: interesting facts

1. The speed of the avalanche can reach 100-300 km / h. A powerful air wave instantly turns houses into ruins, crushes rocks, takes down cableways, uproots trees and destroys all life around.
2. Avalanches can descend from any mountains. The main thing is that they are covered with a snow cover. If in a certain area for 100 years there were no avalanches, then there is always a possibility that they can arise at any time.
3. Approximately from 40 thousand to 80 thousand people during the First World War parted ways with life, they remained buried under avalanches in the Alps. The data are approximate.
4. In America (California), people surrounded Mount St. Gabriel with deep moats. Their sizes are equal to football fields. Avalanches descending from the mountain linger in these ditches and do not roll to populated areas.
5. This destructive natural phenomenon is called differently in different peoples. The Austrians use the word "shnelaelaan", which means "snow stream", Italians say "valanga", the French - "avalansh". We call this phenomenon an avalanche.