• Avalanche – a powerful snowfall that occurs on steep mountain slopes where snow cover is established.

• They appear in the mountains.
• An avalanche is accompanied by the formation air pre-shock wave,
• producing the greatest destruction.

• With a slope steepness of 45 degrees, avalanches occur after every snowfall.
• If the steepness of the slope is 20-30 degrees and there is little vegetation on the slope, then avalanches occur after heavy snowfalls or when a large mass of snow accumulates at the top of the slope.

• long snowfall,
• intensive snow melting,
• earthquake, strong wind
• explosions causing shaking of mountain slopes and air fluctuations
• activities of people.

• It consists in the fact that a large amount of snow with enormous force and high speed sweeps away everything in its path. Huge masses of snow set in motion can slide along the surface of the slope at speeds of up to 100 km/h

• “Even in the last century, in the Alps, people covered in snow were helped to find large, strong St. Bernard dogs, named after the high-mountain monastery of St. Bernard, where they were bred. Near Paris, in a special dog cemetery, there is a monument to St. Bernard Barry, who saved 40 people. These good-natured large dogs found more than 2,000 people in the mountains. Now the St. Bernards have been replaced by East European Shepherds.”

• Preventive

• Removing snow accumulated on the slopes with targeted shots from snow guns.

• Engineering

• Construction of tunnels, galleries, canopies to cover individual areas, installation of avalanche cutters, fender wedges.

• Cancel any trip to the mountains if:
• There is or has just been heavy snowfall;
• Poor visibility conditions developed;
• Weather conditions have changed dramatically

• The most dangerous period for avalanches is spring-summer.
• As a rule, avalanches occur during the day from 10 a.m. until sunset.

• If there is danger of an avalanche, listen to radio messages.

• If you find yourself in the mountains during an avalanche, try to run away from it.

• Try to take cover behind a rock ledge, in a recess.

• Once in the snow mass, make “swimming” movements with your hands.

Important information Freshly fallen snow seems light to us,
like fluff, its cubic meter weighs only 50-60 kg.
A cubic meter of compacted snow already weighs
300-400 kg.
Spring, saturated with water, the same
cubic meter becomes heavier almost
twice.

SNOW - Dangerous!

AVALANCHES

HOW AVALANCHES ARE BORN

Avalanche development

Dry avalanche

WHO IS DYING?

Victims suffocate or

The minutes count down

WHAT DO YOU NEED TO KNOW?

THE AVALANCHE HAS CAUGHT

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An avalanche is a rapid descent of snow cover from a mountain slope under the influence of gravity.

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Avalanche types

There are 3 main types of avalanches: wasp, flume and jumping. Osov - snow landslide. It does not have a specific vanishing channel. Often a snow slope hundreds of meters long breaks off and slides down. Chute avalanches carry snow along a strictly defined channel, treeless depressions in the slopes, and chutes. Jumping avalanches - freely falling to the valley floor through steep sections of rock or ice.

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Avalanche of loose snow (avalanche from a point)

From a distance, it seems that the avalanche starts from one point and, moving along the slope, fan out into a triangle.

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Snow board avalanches (line avalanches)

The collapse of snow boards occurs when one or more layers, which have a certain internal adhesion, are torn off in blocks from the snow layers along a linear crack formed in the snow.

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Attention: Most snow boards originate on slopes with a steepness of 30° - 45°, but water-snow flows can disappear at slope angles less than 12°!

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Avalanche caused by the collapse of cornices

Cornices form when wind-blown snow settles horizontally on sharp points in the terrain, such as ridge tops and canyon walls.

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Signs of avalanche danger

Height of old snow; Condition of the underlying surface; Extremely favorable conditions for avalanches are created on the surface of glaciers; Height of freshly fallen snow; The sight of freshly fallen snow;

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6. Snowfall intensity; 7. Snow settling; 8. Wind at a speed of 7 - 8 meters per second; 9. Air temperature; Avalanches can also be caused by: animals, a loud sound or shot, and a person.

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In case of avalanches!

1. If you are caught in an avalanche, immediately get rid of your backpack, skis, poles, ice axe, as they help you get pulled into the snow flow and hinder your actions. 2. With vigorous movements, try to get to the edge of the avalanche, try to stay on the surface or cling to a tree. Bush, rock ledge.

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3. If it was not possible to get out of the avalanche. Cover your mouth and nose with a hat or scarf to prevent suffocation from snow dust. Group your body, pull your knees towards your stomach, and use your head movements to create free space in front of your face. 4. Immediately after the avalanche stops, determine the direction up and down (saliva flows down from your mouth) and try to get out of the avalanche yourself or push your hand to the surface so that you will be noticed more quickly.

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5. Screaming while under the snow is useless, since the sound from under the snow travels very weakly. Only give signals if you hear rescuers' footsteps. 6. Stay calm. Fight sleep. Move as much as possible to stay warm. The main thing is not to lose composure and hope for help.

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Text content of presentation slides: Snow avalanches 7th grade Developed by life safety teacher Elena Igorevna Koshkina Avalanche is a rapid, sudden movement of snow and (or) ice down steep mountain slopes, posing a threat to the life and health of people, causing damage to economic facilities and the environment. Avalanches form on treeless mountain slopes whose inclination angle is greater than 14°. This is a critical slope at which the snow constantly slides down. An avalanche begins when a layer of freshly fallen snow is 30 cm or when the thickness of old snow is more than 70 cm. The steepness of the slope, most favorable for the formation of an avalanche, is 30-40°. Avalanche speed can reach from 20 to 100 m/s. Thus, a snow avalanche is a mass of snow falling or sliding from steep mountain slopes and moving at an average speed of 20-30 m/s. The fall of a snow avalanche is accompanied by the formation of a pre-avalanche air wave, which produces the greatest destruction. Avalanches are possible in all mountainous areas where snow cover is established. Avalanche-prone areas in Russia are the Kola Peninsula, the Urals, the North Caucasus, Eastern and Western Siberia, and the Far East. The formation of avalanches occurs in an avalanche source, which is a section of a slope and its foot within which an avalanche moves. The reasons for an avalanche are prolonged snowfalls, intense snow melting, as well as explosions during road construction. The impact force of an avalanche can reach from 5 to 50 tons per square meter. Avalanches can cause the destruction of buildings, engineering structures, and cover roads and mountain trails with snow. Residents of mountain villages, tourists, climbers, geologist and other people who find themselves in the mountains and caught in an avalanche may be injured and find themselves under thick snow. Protecting the population from the consequences of avalanches Their prediction is of great importance for protecting the population from the consequences of avalanches. For this purpose, a special surveillance system is in place. Data received from the surveillance system is processed and presented in the form of forecasts. Based on the forecasts received, preventive measures are planned and implemented. In conditions of the threat of avalanches, they organize control over the accumulation of snow in avalanche-prone areas and cause artificial avalanches during the period of their least danger. Protective structures are being built in avalanche-prone areas, rescue equipment is being prepared and rescue operations are being planned. The population is being warned about the danger of avalanches. Rules of conduct in avalanche zones Information about avalanches can be found in the search and rescue service of the Russian Ministry of Emergency Situations. And if you are going to be in an avalanche zone, report your intentions (register) to the search and rescue service of the Russian Ministry of Emergency Situations. Avoid places where avalanches may occur. They most often descend from slopes steeper than 30°; if the slope is without bushes and trees - with a steepness of more than 20°. With a steepness of more than 45°, avalanches occur with almost every snowfall. When an avalanche occurs, if there is a decent distance from you to it, you need to quickly walk or run out of the way of the avalanche to a safe place or take cover behind a rock ledge in a recess. If it is impossible to escape from the avalanche, get rid of all things and take a horizontal position; cover your mouth and nose with a mitten or scarf to prevent suffocation; in the snow, move your arms and legs (pretend swimming) to stay on the surface; try to clear the layer of snow in front of you to make breathing easier. When the avalanche has stopped, try to move up. Don’t lose your composure, don’t fall asleep, save your energy, remember that they are looking for you (there are cases when people were rescued from an avalanche on the fifth and even thirteenth day). Test yourself1. Where do avalanches form?2. Name the reasons for avalanches.

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