Tiger in lamb's skin called innocent, at first glance, white snow Matthias Zdarsky, an Austrian researcher who studied the question of what an avalanche is. Softly falling snow captivates even those who dislike winter - it's too beautiful a picture, like a fairy tale. Yes, 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 serious. After all, 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 History
In all likelihood, an avalanche is a phenomenon that has existed as long as the steep slopes of mountains, and Polybius mentions the first large-scale snowfalls that caused the death 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, “behind” the longest chronicle of disasters. Not for nothing that in the twentieth century inIn some areas, masses were celebrated in memory of those who died under the snow rubble, because in this case, an avalanche is pain and grief for the 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 on the Austro-Italian front died from this natural phenomenon than directly during the hostilities. And December 16, 1916 went down in history as "Black Thursday", when six thousand people were missing in one day. Hemingway, who was in the Alps at the same time and described his definition of what an avalanche means, noted that winter avalanches are terrible, sudden and bring instant death.
Suffered from the "white death" and residents 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 accounting for the dead by and large is not is underway. Tens of thousands of lives and on account of the snow avalanches that broke 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 avalanche mean? This is a beautiful, exciting and dangerous natural phenomenon. The very meaning of the word “avalanche” is also interesting, in the origins of which is the Latin root lab, meaning “instability”, although it got into the Russian language through German, since the definition of Lavine existed in Old German. The Buddhist monk Xuan Zang poetically called them "white dragons", and in the time of Pushkinavalanches were called landslides. In the Alps and the Caucasus, the names of individual mountains, gorges and valleys are already "speaking". For example, the Lan forest or Zeygalan Hoch (“mountain from which avalanches always come down”). Sometimes the ability to read onomastics, although it does not tell everything about snow blockages, can save you 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 mountains under the influence of gravity. It simultaneously creates an air wave, which accounts for a significant part of the destruction and damage that is almost inevitable in this natural disaster.
Having begun its movement, the avalanche can no longer stop, sinking lower and lower and capturing accompanying stones, ice blocks, branches and uprooted trees on its way, turning from ebullient white snow into a dirty mass, remotely resembling a mudflow. The stream can continue its "fascinating journey" until it stops on gentle sections or at the bottom of the valley.
Factors affecting the convergence of snow masses from the mountains
The causes of avalanches largely depend on the old snow - its height and density, the state of the surface under it, as well as the growth of new masses of precipitation. The intensity of snowfalls, subsidence and compaction of the cover and air temperature also affect. In addition, a fairly long open slope (100-500 m) is ideal for starting an avalanche.
The main "architect"this natural phenomenon is not in vain called the wind, since an increase of 10-15 cm is enough for the snow to melt. Temperature is also one of the most important factors that can provoke a disaster. Moreover, if at zero degrees the instability of snow, although it arises quickly, but also passes no less actively (it either melts or an avalanche descends). And when the low temperature is stable, the avalanche period increases.
Seismic fluctuations can also activate the convergence of snow, which is not uncommon for mountainous areas. In some cases, there are enough flights of jet aircraft over dangerous areas.
In general, more frequent snow avalanches are indirectly or directly related to the rapid human economic activity, which is not always reasonable. For example, forest areas cut down today used to serve as a natural protection against snow landslides.
Periodicity
Depending on the frequency, there are intra-annual convergence (for the winter and spring periods) and the long-term average, which includes, respectively, the total frequency of avalanche formation. There are also systematic avalanches (annually or every 2-3 years) and sporadic ones, occurring a maximum of twice per century, which makes them especially unpredictable.
Movement, hotbed of natural phenomena
The nature of the movement of snow masses and the structure of the focus determine the following classification: flume snow avalanches, special and jumping. In the case of the first, the snow moves either along the tray or along a certain channel. Special avalanches while movingcover the entire available area. But with jumpers it’s already more interesting - they are reborn from flume, arising in places of uneven flow. The snow mass has to “jump”, as it were, to overcome certain sections. The latter type is capable of developing the greatest speed, therefore, the danger is very significant.
Snow is insidious and may well creep up unnoticed and inaudibly, falling in an unexpected shock wave, destroying everything in its path. Features of the movement of these natural masses underlie another division into types. A reservoir avalanche stands out in it - this is when the movement occurs relative to the snow surface located below, as well as the ground avalanche - it slides directly on the ground.
Scale
Depending on the damage caused, avalanches are usually divided into especially dangerous (they are also spontaneous) - the volume of material losses amaze the imagination with their scale, and simply dangerous - they impede the activities of various organizations and endanger the peaceful measured life of settlements.
Snow properties
It is also 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 its cozyslopes at temperatures above freezing. The speed of movement here is less than in the previous ones, however, the density of the cover is greater. In addition, the base can freeze, turning into a hard and dangerous layer. For wet avalanches, the raw material is viscous, wet snow, and the mass of each cubic meter is about 400-600 kg, and the speed of movement is 10-20 m/sec.
Volumes
Well, the simplest division - small and almost harmless, medium and dangerous to humans, as well as large ones, which on their way wipe buildings, trees from the face of the earth, turn vehicles into a pile of scrap metal.
Can avalanches be predicted?
Predicting avalanches with a high degree of probability is extremely difficult, 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 noticeable. Passive methods include special shield barriers, forest areas, observation points for dangerous areas. Active actions consist in shelling areas of possible collapses from artillery and mortar installations in order to provoke the convergence of snow masses in small batches.
Snow avalanches sliding down from the mountains in any of the options represent a natural disaster. It doesn't matter if they are small or large. It is extremely important to take into account all the factors influencing the occurrence of snowmasses and their movement along an indefinite route to unknown goals, so as not to sacrifice too expensive gifts to the elements.
All about avalanches: interesting facts
- The speed of an avalanche can reach 100-300 km/h. A powerful air wave instantly turns houses into ruins, crushes rocks, demolishes cable cars, uproots trees and destroys all life around.
- Avalanches can come from any mountains. The main thing is that they are covered with snow cover. If there have been no avalanches in a certain area for 100 years, then there is always the possibility that they can occur at any time.
- About 40,000 to 80,000 people lost their lives during the First World War, they remained buried under avalanches in the Alps. Data is approximate.
- In America (California), people surrounded Mount St. Gabriel with deep ditches. Their sizes are equal to football fields. Avalanches coming down the mountain linger in these ditches and do not roll into settlements.
- This destructive natural phenomenon is called differently by different nations. The Austrians use the word "schneelaanen", which means "snow stream", the Italians say "valanga", the French - "avalanche". We call this phenomenon an avalanche.
