Presentation on the topic of snow avalanches. Presentation on life safety on the topic Snow avalanches (grade 7). Signs of avalanche danger
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SNOW, SNOW, SNOW, SNOW... Freshly fallen snow seems to us light as feathers, its cubic meter weighs only 50-60 kg. A cubic meter of compacted snow already weighs 300-400 kg. In spring, saturated with water, the same cubic meter becomes almost twice as heavy.
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IS SNOW A DANGER? YES! Why is snow dangerous? Avalanches Snow cornices and blows Formation of ice and icicles. Hides dangers Impedes traffic movement Cause of ice
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AVALANCHES 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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HOW AVALANCHES ARE BORN Causes of a snow avalanche: prolonged snowfall, intense snow melting, earthquakes, explosions causing shaking of mountain slopes and air fluctuations, human activity,
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Development of an avalanche Loose snow slides over a denser layer Having accelerated, the mass of snow can rise into the air The avalanche picks up speed, sometimes reaching 350 km/h
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Dry avalanche Dry avalanches consist of loose snow and move especially rapidly. They begin with small snow slides, but due to ground shaking and the occurrence of a shock wave they quickly increase
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WHO IS DYING? Statistics on white death victims claim that almost half of them die in small avalanches that travel no more than 200 meters.
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An avalanche can carry up to a million tons of snow from a slope and drive an air shock wave in front of it, which, like a bomb explosion, destroys everything in its path. Anyone who meets her on the road will be crushed.
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Most avalanche victims die very quickly, as a wall of snow rushing at a speed of 100 km/h or more creates a shock wave; it instantly clogs the victim's lungs and airways with snow, and the person dies from suffocation. People who survive this first onslaught die, caught inside an avalanche, which throws them at great speed into rocks, trees and other obstacles.
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Victims suffocate or The deeper a person is buried under an avalanche, the less chance of getting him out of there alive. After all, if a cubic meter of freshly fallen snow weighs only 60-70 kg, then the compacted snow mass of an avalanche presses on the body with the weight of more than a ton, does not allow breathing and simply flattens a person. Many avalanche victims suffocate under a meter-long layer of snow, as fresh air does not reach them. Therefore, rescuers advise that in the event of an accident, if possible, press your palms to your face in order to create at least a small space for air, and then the victim, if he is lucky, can hold out until the rescuers arrive. Victims are suffocated or crushed
Avalanche
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- 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 each 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.
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Slide captions:
Lesson topic: Life Safety Lesson 7th grade
SNOW, SNOW, SNOW, SNOW... Freshly fallen snow seems to us light as feathers, its cubic meter weighs only 50-60 kg. A cubic meter of compacted snow already weighs 300-400 kg. In spring, saturated with water, the same cubic meter becomes almost twice as heavy.
IS SNOW A DANGER? YES! Why is snow dangerous? Avalanches Snow cornices and blows Formation of ice and icicles. Hides dangers Impedes traffic movement Cause of ice
AVALANCHES 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.
HOW AVALANCHES ARE BORN Causes of a snow avalanche: prolonged snowfall, intense snow melting, earthquakes, explosions causing shaking of mountain slopes and air fluctuations, human activity,
Development of an avalanche Loose snow slides over a denser layer Having accelerated, the mass of snow can rise into the air The avalanche picks up speed, sometimes reaching 350 km/h
Dry avalanche Dry avalanches consist of loose snow and move especially rapidly. They begin with small snow slides, but due to ground shaking and the occurrence of a shock wave they quickly increase
WHO IS DYING? Statistics on white death victims claim that almost half of them die in small avalanches that travel no more than 200 meters.
An avalanche can carry up to a million tons of snow from a slope and drive an air shock wave in front of it, which, like a bomb explosion, destroys everything in its path. Anyone who meets her on the road will be crushed.
Most avalanche victims die very quickly, as a wall of snow rushing at a speed of 100 km/h or more creates a shock wave; it instantly clogs the victim's lungs and airways with snow, and the person dies from suffocation. People who survive this first onslaught die, caught inside an avalanche, which throws them at great speed into rocks, trees and other obstacles.
Victims suffocate or The deeper a person is buried under an avalanche, the less chance of getting him out of there alive. After all, if a cubic meter of freshly fallen snow weighs only 60-70 kg, then the compacted snow mass of an avalanche presses on the body with the weight of more than a ton, does not allow breathing and simply flattens a person. Many avalanche victims suffocate under a meter-long layer of snow, as fresh air does not reach them. Therefore, rescuers advise that in the event of an accident, if possible, press your palms to your face in order to create at least a small space for air, and then the victim, if he is lucky, can hold out until the rescuers arrive. Victims are suffocated or crushed
The minutes are counting. People buried in an avalanche are being searched with probes. This must be done quickly, since after 20 minutes half of the victims die. The chance of rescue increases if rescuers and victims have “buried search devices” that send and receive signals.
WHAT DO YOU NEED TO KNOW? Avalanche dangerous time Within 3-5 days after heavy snow Thaw after frost Strong wind In spring from 12 to 18 o'clock Signs of avalanche danger Slope steepness from 20 to 50 degrees Lack of tree and shrub vegetation Signs of previous avalanches “Pellets” Snow cornices and ridges
THE AVALANCHE HAS CAUGHT Get rid of everything that can serve as a “sail” (skis, board, poles) Do not resist the avalanche, but try to “swim” to the surface When slowing down, group yourself by closing your mouth After stopping, determine the top and begin to free up space without stretching your legs
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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 avalanche)
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 ax, 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.
