Matyas Zdarski, an innocent, seemingly white snow, named a tiger in the skin of a lamb, an Austrian researcher who studied the question of what an avalanche is. The softly falling snow captivates even those who do not like winter - the picture is too beautiful, looking like a fairy tale. And the crystal stars smoothly flying to the ground create a deceptive impression of fragility, defenseless tenderness. However, excessively active snowfalls are fraught with danger, and a serious one. Indeed, not only snowdrifts, but also avalanches can grow from small snowflakes. So what is an avalanche? The definition of this concept is given below. And now a little history.
A brief excursion into history
In all likelihood, an avalanche is a phenomenon that exists as much as the steep slopes of the mountains, and Polybius also mentions the first large-scale convergence of snow that caused the deaths of hundreds of people in the context of the history of the campaign of the Carthaginian army through the Alps. And in general, this mountain range, chosen by tourists and climbers, has the longest chronicle of disasters. It is not in vain that in the 20th century masses were served in some districts in memory of those who died under snow blockages, because in this case an avalanche is pain and sorrow for relatives and friends of those who suffered from its descent. It is also noteworthy that in one of the last winters of the First World War, more soldiers died on this Austro-Italian front from this natural phenomenon than directly during the hostilities. And on December 16, 1916, it went down in history as “Black Thursday”, when six thousand people were missing in one day. Hemingway, who was in the Alps during the same time period and described his definition of what an avalanche means, noted that winter landslides are terrible, sudden and bring about instant death.
The inhabitants of Norway, Iceland, Bulgaria, the United States, the Russian Federation, Canada, as well as Asian countries: Turkey, Nepal, Iran, Afghanistan suffered from the "white death", and in the latter there is no record of the dead. Tens of thousands of lives and on account of snow avalanches that have torn from Mount Huascaran 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. The very meaning of the word "avalanche" is also interesting, at the source of which is the Latin root lab, meaning "instability", although it already entered the Russian language through German, since the definition of Lavine existed in ancient German. The Buddhist monk Xuan Zang poetically called them "white dragons", and during the time of Pushkin, avalanches were called landslides. In the Alps and in the Caucasus, the names of individual mountains, gorges and valleys are already “speaking”. For example, Lansky forest or Zeygalan Hoh ("the mountain with which avalanches always descend"). Sometimes the ability to read onomastics, although it will not tell everything about the snow blockages, but can save from unforeseen circumstances.
What is an avalanche?
An avalanche is a type of landslide, a significant mass of snow that moves or even falls from the slopes of the mountains under the influence of gravity. It simultaneously creates an air wave, which accounts for a significant part of the destruction and damage that are almost inevitable in this natural disaster.
Having started its movement, the avalanche can no longer stop, dropping lower and grabbing accompanying stones, ice blocks, branches and trees torn from the root, turning from boiling white snow into a dirty mass remotely resembling a mudflow. The stream can continue its “fascinating journey” until it stops at gentle sections or at the bottom of the valley.
Factors affecting the convergence of snow masses from the mountains
The reasons for the convergence of avalanches largely depend on the old snow - its height and density, the state of the surface under it, as well as on the growth of new masses of precipitation. Also affects the intensity of snowfall, subsidence and compaction of the cover and air temperature. In addition, a sufficiently long open slope (100-500 m) is optimal for starting an avalanche path.
It is not in vain that the main “architect” of this natural phenomenon is called the wind, since an increase of 10-15 cm is sufficient for the snow to melt. Temperature is also one of the most important factors that can trigger a catastrophe. Moreover, if at zero degrees the snow instability, although it occurs quickly, is no less active (it either melts or the avalanche is coming off). And when the low temperature is stable, the avalanche period increases.
Seismic vibrations can also activate the convergence of snow, which is not uncommon in mountainous areas. In some cases, there are enough flights of jet aircraft over hazardous areas.
In general, frequent snow avalanches are indirectly or directly related to the rapid economic activity of man, which is not always reasonable. For example, the forests cut down today used to be a natural defense against snow landslides.
Periodicity
Depending on the repeatability, they distinguish between intra-annual convergence (for winter and spring periods) and long-term average convergence, which includes, respectively, the total frequency of avalanche formation. Systematic avalanches are also distinguished (annually or every 2-3 years) and sporadic avalanches that occur at most twice in a century, which makes them especially unpredictable.
Movement, the center of a natural phenomenon
The nature of the movement of snow masses and the structure of the outbreak determine the following classification: channel snow avalanches, special and jumping. In the case of the former, snow moves either along the tray or along a specific channel. Special avalanches during movement cover the entire accessible area. But with jumpers it’s already more interesting - they are reborn from tray ones, arising in places of runoff irregularities. The snow mass has to “bounce”, as it were, to overcome certain areas. The latter type is capable of developing the highest speed, therefore, the danger is very significant.
The snow is treacherous and may well creep in unnoticed and inaudibly, having collapsed in a shock unexpected wave, destroying everything in its path. The peculiarities of the movement of these natural masses underlie yet another division into types. A formation avalanche stands out in it - this is when the movement occurs relative to the snow surface located below, and also the ground - it glides directly on the ground.
Scale
Depending on the damage caused, avalanches are usually divided into especially dangerous (they are also spontaneous) - the volumes of material losses amaze the imagination with their scales, and simply dangerous - they complicate the activities of various organizations and threaten the peaceful, measured life of settlements.
Snow properties
It is important to note the classification associated with the properties of the snow itself, which is the basis of the avalanche. Allocate dry, wet and wet. The former are characterized by a high convergence rate and a powerful destructive air wave, and the masses themselves are formed at sufficiently low temperatures after significant snowfalls. A wet avalanche is snow that has chosen to leave the cozy slopes at temperatures above zero. The speed of movement here is less than the previous ones, however, and the density of the cover is greater. In addition, the base can freeze, turning into a hard and dangerous layer. For wet avalanches, viscous, wet snow is the raw material, and the mass of each cubic meter is about 400-600 kg, and the speed is 10-20 m / s.
Volumes
Well, the simplest division is small and almost harmless, medium and dangerous for humans, as well as large ones, which on their way erase buildings, trees and turn transport into a pile of scrap metal.
Is it possible to predict the occurrence of avalanches?
It is extremely difficult to predict the convergence of avalanches, 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 various and very tangible. Passive methods include special shield barriers, forests, observation points for dangerous areas. Active action consists in shelling sections of possible landslides from artillery and mortar installations in order to provoke the convergence of snow masses in small batches.
Snow avalanches sliding from the mountains in any of the options are a natural disaster. It doesn’t matter whether they are small or large. It is extremely important to consider all the factors affecting the occurrence of snow masses and their movement along an indefinite route to unknown goals, so as not to sacrifice too expensive gifts to the elements.
