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Meteorological natural phenomena - OBZH: Fundamentals of life safety. Hazardous weather phenomena The most dangerous natural phenomena

20.06.2020

Target: Familiarize yourself with safety precautions for various hazardous weather conditions

Time: 1 hour

Lesson type: combined lesson

DURING THE CLASSES

I. Organizational moment.

II. Repetition of the material covered.

1. Conversation on questions.

2. Message of the topic of the lesson.

III. Exploring a new topic.

Weather This is the main factor on which human safety in natural conditions depends. Some weather phenomena significantly complicate the stay of a person in the natural environment.

When going on a hike, you need to find out how the weather changes in the places of the planned vacation at different times of the year.

It is known that for any area and each type of hiking (hiking, mountain, water, skiing) it is possible to distinguish the most favorable and unfavorable seasons in terms of weather conditions. So, for amateur mountain hikes, the second half of summer (July - August) is considered the most favorable season in almost all regions of the country.

For ski tourism in the middle lane, March is preferable, and in the northern regions - March - April.

In the natural environment, a person most often encounters such weather phenomena as precipitation (rain, snow, hail). In a city or village, they do not cause much inconvenience, as a person can hide in buildings, public transport, etc.

Another thing in the natural environment, where you need to be able to provide protection from adverse weather, using equipment and natural shelters.

Experienced tourists advise in case of short-term heavy precipitation (heavy rain) to stop at the first convenient place and wait out the bad weather in shelter, under an awning or a cape.

You can continue to move in rain and snow on a technically simple section, along trails, on flat terrain, covered with a cape. Immediately after the transition in the rain (or in the snow), it is necessary to organize a bivouac, best of all in a shelter where you can make a fire, change clothes, dry your wet clothes and shoes.

What to do during a thunderstorm

Particular care must be taken during thunderstorms. This weather phenomenon is associated with the development of cumulonimbus clouds and the accumulation of large electrical charges in them. The greatest danger to humans is a direct lightning strike.

Lightning is a giant electrical discharge that occurs between thunderclouds or between clouds and the earth. The currents generated in the earth after lightning strikes on the earth's surface are also dangerous.

Harbingers of a thunderstorm are powerful cumulonimbus clouds, multiple flashes of lightning, thunder. Just before the start of a thunderstorm, there is usually a lull or the wind changes direction, then suddenly the wind (swell) increases sharply and it begins to rain.

When a thunderstorm approaches, before the onset of rain, you should try to find a safe place, set up a bivouac or make a shelter.

If you are on a hill when a thunderstorm approaches (on a ridge, hill, steep slope), you need to go down as quickly as possible to avoid being hit by lightning.

If you are in the water, you need to get ashore quickly.

If you are in a forest, it is best to take cover among low trees with dense undergrowth.

Remember that among trees, birch and maple are less susceptible to direct lightning strikes, and oak and poplar are the most susceptible.

In open areas, you should choose sandy or rocky areas, you can hide in a dry hole, ditch, ravine.

In the mountains, it is undesirable to seek shelter from a thunderstorm in small grottoes (shallow caves with a wide entrance), rock pits, depressions, as there is a danger of being struck by currents formed in the ground after lightning strikes.

If you still had to hide in a cave, grotto, large depression, you can’t be at the entrance or in the far corner of such a place, the position of a person is safe when the distance between him and the walls is at least 1 m.

Having chosen a place in the shelter, you need to sit down, pulling your knees to your chest and wrapping your arms around them. It is unacceptable to touch the head, back or other parts of the body with the surface of rocks or soil.

To isolate the torso and legs from the earth's surface, you can use a backpack and other items of equipment, wrapping these items in plastic wrap.

During a thunderstorm, do not:

be located next to the railway track, near a reservoir, near a tall object (tree);
lean head, back or other parts of the body against the surface of rocks, tree trunks;
stop at the edges of the forest and forest clearings.

What to do during a blizzard

In winter, a considerable danger to a person in natural conditions (ski trip) is a snowstorm, a snowstorm. The blizzard is characterized by strong winds with snow. It can last from several hours to several days.

In a blizzard, with strong wind and cold, a person’s normal breathing is disturbed, the heat-shielding properties of clothing are reduced, due to poor visibility, he loses his bearings, can get lost, exhausted and die.

In order not to get into a snowstorm on the route, you need to prepare for it in time and know the signs of its approach.

A blizzard does not come suddenly. Before it begins, there is an increase in air temperature and a gradual increase in wind speed. A harbinger of a blizzard is the appearance of a dark gray or black cloud growing on the horizon with changing outlines. The wind gradually intensifies and becomes gusty, which raises the snow and disperses the snow. A cloud covers the entire sky, and a blizzard begins.

REMEMBER! It is best to wait out the blizzard in the bivouac camp. If the group is moving along the route when a snowstorm approaches, it is necessary to stop immediately, set up camp and wait for it to end.

If, when a blizzard is approaching, there is an opportunity to hide in the forest, it is necessary to move, having previously put on windbreakers, down jackets, insulated mittens.

The primary task facing a group of tourists before or after the onset of a blizzard is to set up a bivouac. When pitching a tent, you should find at least partial shelter from the wind. The tent is set up with an entrance from the leeward side, its extensions are fixed by sticking them into the snow with skis or ski poles. After setting up the tent, backpacks are brought in, which are placed at the rear windward wall and at the corners of the tent.

When setting up a bivouac in a snowstorm, you must not leave the tent. A tourist who has moved away from the tent and lost sight of the camp must return back in his footsteps. If the tracks are covered, you should stop and take all measures to independently arrange a temporary shelter.

Signs of bad weather

If it is clear during the day, and in the evening the clouds thicken, then rain or a change in weather should be expected.

Wavy (altocumulus) clouds resembling ripples or crests of waves are a sure sign of the onset of inclement weather after a few hours.

There may be other signs of bad weather as well.

The air temperature in winter rises slightly, warming sets in. In summer, the difference between the air temperature during the day and at night decreases, in the evening it is warmer than during the day.
The wind intensifies, especially in the evening, the regular daily changes in local winds are disturbed.
Cloudiness increases, clouds move in the opposite direction or across the direction in which the wind blows near the earth's surface.
The sun sets in a cloud, the evening dawn is bright red.

IV. Summary of the lesson.

1. Fixing the topic of the lesson.

Why do you need to know the weather forecast before going out into nature?
How can you protect yourself from atmospheric precipitation in natural conditions?
How dangerous is a thunderstorm for a person in natural conditions?

2. Homework

List the precautions you should take to protect yourself from a blizzard. Write them down in a safety diary.

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Weather is the main factor on which human safety in natural conditions depends. Some weather phenomena significantly complicate the stay of a person in the natural environment. When going on a hike, you need to find out how the weather changes in the places of the planned vacation at different times of the year. Weather is the main factor

slide 3

From the experience of organizing outdoor activities, it has been established that for any area and each type of hiking trip (hiking, mountain, water, skiing), it is possible to distinguish the most favorable and unfavorable seasons in terms of weather conditions. We know that...

slide 4

So, for amateur mountain hikes, the second half of summer (July - August) is considered the most favorable season in almost all regions of the country. For ski tourism in the middle lane, March is preferable, and in the northern regions - March - April. For mountain and ski trips

slide 5

Experienced tourists advise in case of short-term heavy precipitation (heavy rain) to stop at the first convenient place and wait out the bad weather in shelter, under an awning or a cape. In bad weather

slide 6

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Slide 8

Lightning is a giant electrical discharge that occurs between thunderclouds or between clouds and the ground. The currents generated in the ground during lightning strikes on the earth's surface are also dangerous. Lightning

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- If you are on a high ground (on a ridge, hill, steep slope) when a thunderstorm approaches, you need to go down as quickly as possible to avoid being hit by lightning. - If you are in the water, you need to get ashore quickly. - In the forest, it is best to hide among low trees with dense undergrowth. - Remember that among trees, birch and maple are less susceptible to direct lightning strikes, and oak and poplar are the most susceptible. First measures

slide 11

In open areas, you should choose sandy or rocky areas, you can hide in a dry hole, ditch, ravine. In the mountains, it is undesirable to seek shelter from a thunderstorm in small grottoes (shallow caves with a wide entrance), rock pits, depressions, as there is a danger of being struck by currents formed in the ground after a lightning strike. We take cover

slide 12

If you still had to take refuge in a cave, grotto, large depression, you can’t be at the entrance or in the far corner of such a place, the position of a person is safe when the distance between him and the walls is at least 1 m. In a cave

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During a thunderstorm it is impossible: to be located next to the railway track, near a reservoir, near a high object (tree); lean head, back or other parts of the body against the surface of rocks, tree trunks; stop at the edges of the forest and forest clearings. Remember!

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What to do during a blizzard A blizzard does not come suddenly. Before it begins, there is an increase in air temperature and a gradual increase in wind speed. A harbinger of a blizzard is the appearance of a dark gray or black cloud growing on the horizon with changing outlines. The wind gradually intensifies and becomes gusty, which raises the snow and disperses the snow. A cloud covers the entire sky, and a blizzard begins.

slide 16

What to do during a blizzard It is best to wait out a blizzard in a bivouac camp. If the group is moving along the route when a blizzard approaches, it is necessary to immediately stop, set up camp and wait for it to end.

slide 17

What to do during a snowstorm The primary task facing a group of tourists before or after the onset of a snowstorm is to set up a bivouac. When pitching a tent, you should find at least partial shelter from the wind. The tent is set up with an entrance on the leeward side, its extensions are fixed by sticking them into the snow with skis or ski poles. After setting up the tent, backpacks are brought in, which are placed at the rear windward wall and at the corners of the tent. Signs of worsening weather If it is clear during the day and the clouds thicken in the evening, then rain or a change in weather should be expected. Wavy (altocumulus) clouds resembling ripples or crests of waves are a sure sign of the onset of inclement weather after a few hours. The air temperature in winter rises slightly, warming sets in. In summer, the difference between the air temperature during the day and at night decreases, in the evening it is warmer than during the day. The wind intensifies, especially in the evening, the regular daily changes in local winds are disturbed. Cloudiness increases, clouds move in the opposite direction or across the direction in which the wind blows near the earth's surface. The sun sets in a cloud, the evening dawn has a bright red color.

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Questions and tasks Why do you need to know the weather forecast before going out into nature? How can you ensure your protection from atmospheric precipitation in natural conditions? How dangerous is a thunderstorm for a person in natural conditions? How can you ensure your safety if a thunderstorm has caught you in nature? 5. What precautions should be taken to protect against snowstorms?

These processes and phenomena are associated with various atmospheric processes, and above all with processes occurring in the lower layer of the atmosphere - the troposphere. In the troposphere is about 9 /10 of the total mass of air. Under the influence of solar heat entering the earth's surface and the force of gravity in the troposphere, clouds, rain, snow, wind.

Air in the troposphere moves in both horizontal and vertical directions. Strongly heated air near the equator expands, becomes lighter and rises. There is an upward movement of air. For this reason, a belt of low atmospheric pressure forms near the Earth's surface near the equator. At the poles, due to low temperatures, the air cools, becomes heavier and falls down. There is a downward movement of air. For this reason, near the surface of the Earth near the poles, the pressure is high.

In the upper troposphere, on the contrary, above the equator, where ascending air currents predominate, the pressure is high, and above the poles it is low. Air is constantly moving from an area of high pressure to an area of low pressure. Therefore, the air that has risen above the equator spreads towards the poles. But due to the rotation of the Earth around its axis, the moving air does not reach the poles. As it cools, it becomes heavier and sinks at approximately 30° N and S, forming areas of high pressure in both hemispheres.

Large volumes of troposphere air with homogeneous properties are called air masses. The properties of air masses depend on the territories over which they formed. Moving, air masses retain their properties for a long time, and when they meet, they interact with each other. The movement of air masses and their interaction determine the weather in those places where these air masses come. The interaction of various air masses leads to the formation of moving atmospheric vortices in the troposphere - cyclones and anticyclones.

A cyclone is a flat ascending vortex with low atmospheric pressure in the center. The diameter of a cyclone can be several thousand kilometers. The weather during the cyclone is overcast, with strong winds.

An anticyclone is a flat descending eddy with high atmospheric pressure, with a maximum in the center. In an area of high pressure, air does not rise, but falls. The air spiral unwinds in the northern hemisphere clockwise. The weather during the anticyclone is cloudy, without precipitation, the wind is weak.

With the movement of air masses, with their interaction, the emergence of dangerous meteorological phenomena that can cause natural disasters is associated. This iPhones and hurricanes, storms, snow storms, tornadoes, thunderstorms, droughts, severe frosts and fogs.

Natural hazards are extreme climatic or meteorological phenomena that occur naturally at one point or another on the planet. In some regions, such hazards may occur with greater frequency and destructive force than in others. Hazardous natural phenomena develop into natural disasters when the infrastructure created by civilization is destroyed and people die.

1. Earthquakes

Among all natural hazards, the first place should be given to earthquakes. In places of breaks in the earth's crust, tremors occur, which cause vibrations of the earth's surface with the release of gigantic energy. The resulting seismic waves are transmitted over very long distances, although these waves have the greatest destructive power in the epicenter of the earthquake. Due to strong vibrations of the earth's surface, mass destruction of buildings occurs.
Since there are quite a lot of earthquakes, and the surface of the earth is quite densely built up, the total number of people in history who died precisely as a result of earthquakes exceeds the number of all victims of other natural disasters and amounts to many millions. For example, over the past decade around the world, about 700 thousand people have died from earthquakes. From the most devastating shocks, entire settlements instantly collapsed. Japan is the most earthquake-affected country, and one of the most catastrophic earthquakes occurred there in 2011. The epicenter of this earthquake was in the ocean near the island of Honshu, according to the Richter scale, the magnitude of the shocks reached 9.1 points. Powerful aftershocks and the subsequent devastating tsunami disabled the nuclear power plant in Fukushima, destroying three of the four power units. Radiation covered a large area around the station, rendering densely populated areas so valuable in Japanese conditions uninhabitable. A colossal tsunami wave turned into a mess what the earthquake could not destroy. More than 16 thousand people officially died, among which another 2.5 thousand who are considered missing can be safely added. In this century alone, devastating earthquakes have occurred in the Indian Ocean, Iran, Chile, Haiti, Italy, and Nepal.

2. Tsunami waves

A specific water disaster in the form of tsunami waves often results in numerous casualties and catastrophic destruction. As a result of underwater earthquakes or shifts of tectonic plates in the ocean, very fast, but hardly noticeable waves arise, which grow into huge ones as they approach the coast and enter shallow water. Most often, tsunamis occur in areas with increased seismic activity. A huge mass of water, quickly moving ashore, blows everything in its path, picks it up and carries it deep into the coast, and then carries it back to the ocean with a reverse current. Humans, unable to feel danger like animals, often do not notice the approach of a deadly wave, and when they do, it is too late.
A tsunami usually kills more people than the earthquake that caused it (the latter in Japan). In 1971, the most powerful tsunami ever observed occurred there, the wave of which rose 85 meters at a speed of about 700 km / h. But the most catastrophic was the tsunami observed in the Indian Ocean in 2004, the source of which was an earthquake off the coast of Indonesia, which claimed the lives of about 300 thousand people along a large part of the coast of the Indian Ocean.

A tornado (in America this phenomenon is called a tornado) is a fairly stable atmospheric vortex, most often occurring in thunderclouds. He is a visa...

3. Volcanic eruption

Throughout its history, mankind has remembered many catastrophic volcanic eruptions. When the pressure of magma exceeds the strength of the earth's crust in the weakest places, which are volcanoes, this ends with an explosion and outpourings of lava. But the lava itself is not so dangerous, from which you can simply get away, as hot pyroclastic gases rushing from the mountain, pierced here and there by lightning, as well as a noticeable effect on the climate of the strongest eruptions.
Volcanologists count about half a thousand dangerous active volcanoes, several dormant supervolcanoes, not counting thousands of extinct ones. So, during the eruption of the Tambora volcano in Indonesia, for two days the surrounding lands were plunged into darkness, 92 thousand inhabitants died, and a cold snap was felt even in Europe and America.
List of some strong volcanic eruptions:

Volcano Laki (Iceland, 1783). As a result of that eruption, a third of the population of the island died - 20 thousand inhabitants. The eruption lasted for 8 months, during which flows of lava and liquid mud erupted from volcanic cracks. The geysers have never been more active. Living on the island at that time was almost impossible. The crops were destroyed, and even the fish disappeared, so the survivors experienced hunger and suffered from unbearable living conditions. This may be the longest eruption in human history.
Volcano Tambora (Indonesia, Sumbawa Island, 1815). When the volcano exploded, the sound of this explosion spread over 2,000 kilometers. Ash covered even the remote islands of the archipelago, 70 thousand people died from the eruption. But even today, Tambora is one of the highest mountains in Indonesia that retains volcanic activity.
Volcano Krakatoa (Indonesia, 1883). 100 years after Tambora, another catastrophic eruption occurred in Indonesia, this time "blowing the roof off" (literally) the Krakatoa volcano. After the catastrophic explosion that destroyed the volcano itself, frightening peals were heard for another two months. A huge amount of rocks, ash and hot gases were thrown into the atmosphere. The eruption was followed by a powerful tsunami with a wave height of up to 40 meters. These two natural disasters together destroyed 34,000 islanders along with the island itself.
Volcano Santa Maria (Guatemala, 1902). After a 500-year hibernation in 1902, this volcano woke up again, starting the 20th century with the most catastrophic eruption, which resulted in the formation of a one and a half kilometer crater. In 1922, Santa Maria again reminded of itself - this time the eruption itself was not too strong, but a cloud of hot gases and ash brought death to 5 thousand people.

4. Tornadoes

There are a wide variety of dangerous places on our planet, which have recently begun to attract a special category of extreme tourists looking for...

A tornado is a very impressive natural phenomenon, especially in the USA, where it is called a tornado. This is an air stream twisted in a spiral into a funnel. Small tornadoes resemble slender narrow pillars, and giant tornadoes can resemble a mighty carousel directed to the sky. The closer to the funnel, the stronger the wind speed, it begins to drag along ever larger objects, up to cars, wagons and light buildings. In the "tornado alley" of the United States, entire city blocks are often destroyed, people die. The most powerful vortices of category F5 reach a speed of about 500 km/h in the center. The state of Alabama suffers the most every year from tornadoes.

There is a kind of fire tornado, which sometimes occurs in the area of massive fires. There, from the heat of the flame, powerful ascending currents are formed, which begin to twist into a spiral, like an ordinary tornado, only this one is filled with flame. As a result, a powerful draft is formed near the surface of the earth, from which the flame grows even stronger and incinerates everything around. When the catastrophic earthquake hit Tokyo in 1923, it caused massive fires that led to the formation of a fiery tornado that rose 60 meters. The column of fire moved towards the square with frightened people and burned 38 thousand people in a few minutes.

5. Sandstorms

This phenomenon occurs in sandy deserts when a strong wind rises. Sand, dust and soil particles rise to a sufficiently high height, forming a cloud that dramatically reduces visibility. If an unprepared traveler gets into such a storm, he can die from grains of sand falling into the lungs. Herodotus described history as in 525 BC. e. in the Sahara, a 50,000-strong army was buried alive by a sandstorm. In Mongolia, 46 people died as a result of this natural phenomenon in 2008, and two hundred people suffered the same fate the year before.

Throughout the history of mankind, the strongest earthquakes have repeatedly caused enormous damage to people and caused a huge number of casualties among the population ...

6. Avalanches

From the snow-covered mountain peaks, snow avalanches periodically descend. Climbers especially often suffer from them. During World War I, up to 80,000 people died from avalanches in the Tyrolean Alps. In 1679, five thousand people died in Norway from snowmelt. In 1886, there was a major disaster, as a result of which the "white death" claimed 161 lives. The records of the Bulgarian monasteries also mention the human victims of snow avalanches.

7 Hurricanes

They are called hurricanes in the Atlantic and typhoons in the Pacific. These are huge atmospheric vortices, in the center of which the strongest winds and sharply reduced pressure are observed. In 2005, the devastating hurricane Katrina swept over the United States, which especially affected the state of Louisiana and the densely populated New Orleans located at the mouth of the Mississippi. 80% of the city was flooded, killing 1836 people. Notable destructive hurricanes have also become:

Hurricane Ike (2008). The diameter of the eddy was over 900 km, and in its center the wind was blowing at a speed of 135 km/h. In the 14 hours that the cyclone moved across the United States, it managed to cause $30 billion worth of damage.
Hurricane Wilma (2005). This is the largest Atlantic cyclone in the history of meteorological observations. A cyclone that originated in the Atlantic made landfall several times. The amount of damage inflicted by him amounted to $ 20 billion, 62 people died.
Typhoon Nina (1975). This typhoon was able to breach China's Bankiao Dam, causing the dams below to collapse and causing catastrophic flooding. The typhoon killed up to 230,000 Chinese.

8. Tropical cyclones

These are the same hurricanes, but in tropical and subtropical waters, which are huge low-pressure atmospheric systems with winds and thunderstorms, often exceeding a thousand kilometers in diameter. Near the surface of the earth, winds in the center of the cyclone can reach speeds of over 200 km/h. Low pressure and wind cause the formation of a coastal storm surge - when colossal masses of water are thrown ashore at high speed, washing everything in their path.

It is difficult to scare a Russian person with anything, especially bad roads. Even safe tracks take thousands of lives a year, let alone those a...

9. Landslide

Prolonged rains can cause landslides. The soil swells, loses its stability and slides down, taking with it everything that is on the surface of the earth. Most often, landslides occur in the mountains. In 1920, the most devastating landslide occurred in China, under which 180 thousand people were buried. Other examples:

Bududa (Uganda, 2010). Due to mudflows, 400 people died, and 200 thousand had to be evacuated.
Sichuan (China, 2008). Avalanches, landslides and mudflows caused by an 8-magnitude earthquake claimed 20,000 lives.
Leyte (Philippines, 2006). The downpour caused a mudflow and a landslide that killed 1,100 people.
Vargas (Venezuela, 1999). Mudflows and landslides after heavy rains (almost 1000 mm of precipitation fell in 3 days) on the northern coast led to the death of almost 30 thousand people.

10. Fireballs

We are accustomed to ordinary linear lightning accompanied by thunder, but ball lightning is much rarer and more mysterious. The nature of this phenomenon is electrical, but scientists cannot yet give a more accurate description of ball lightning. It is known that it can have different sizes and shapes, most often these are yellowish or reddish luminous spheres. For unknown reasons, ball lightning often ignores the laws of mechanics. Most often they occur before a thunderstorm, although they can appear in absolutely clear weather, as well as indoors or in the cockpit. The luminous ball hangs in the air with a slight hiss, then it can start moving in an arbitrary direction. Over time, it seems to shrink until it disappears altogether or explodes with a roar.

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Meteorological emergencies are dangerous natural processes and phenomena that occur in the atmosphere under the influence of various natural factors or their combinations, which have or may have a damaging effect on people, farm animals and plants, economic facilities and the natural environment.

Meteorological emergencies include:

meteorological phenomena associated with the movement of air in the atmosphere;
meteorological phenomena associated with high and low temperatures;
meteorological phenomena associated with precipitation;
meteorological phenomena associated with the deposition of ice and sticking of wet snow on electrical wires;
meteorological phenomena associated with the formation of ice on the roads;
fog.

Meteorological phenomena associated with the movement of air in the atmosphere include:

strong wind- movement of air relative to the earth's surface with a speed or horizontal component of more than 14 m/s;
vortex- atmospheric formation with rotational movement of air around a vertical or inclined axis;
Hurricane- wind of destructive force and considerable duration, the speed of which exceeds 32 m/s. Hurricane Katrina began forming on August 23, 2005 in the Bahamas. The wind speed during the hurricane reached 280 km/h. On August 27, 2005, the hurricane passed over the coast of Florida near Miami and turned towards the Gulf of Mexico. The most severe damage was caused to New Orleans in Louisiana, where about 80% of the city's area was under water. The disaster killed 1,836 people;
cyclone- an atmospheric disturbance with low air pressure and hurricane wind speeds that occurs in tropical latitudes and causes great destruction and death of people. The local name for a tropical cyclone is typhoon;
storm - prolonged very strong wind with a speed of more than 20 m/s, causing severe waves at sea and destruction on land;
tornado - a strong small-scale atmospheric vortex with a diameter of up to 1000 m, in which the air rotates at a speed of up to 100 m/s, which has a great destructive force (Fig. 8.8). A tornado is the most dangerous natural phenomenon associated with the movement of air in the atmosphere;
flurry - a sharp short-term wind force up to 20–30 m/s and higher, accompanied by a change in its direction and associated with convective processes;
dust storm- the transfer of large amounts of dust or sand by strong winds, accompanied by a deterioration in visibility, blowing the topsoil along with seeds and young plants, falling asleep crops and highways. In case of a dust storm, you should cover your face with a gauze bandage, a scarf, a piece of cloth, and your eyes with glasses.

Rice. 8.8.

Meteorological phenomena associated with high and low temperatures include:

hard frost- this is a meteorological phenomenon, when the expected and observed negative anomalies of average daily air temperatures in November - March are from -10 to -25 ° C for at least 5 days and more or the minimum air temperature is close to extreme values;
heatwave is a meteorological phenomenon when the expected and observed positive anomalies of average daily air temperatures in May-August for at least 5 days are +27°C or more, or the maximum air temperature is close to extreme values.

In the summer, a dangerous agrometeorological phenomenon can occur - drought. Drought- this is a complex of meteorological factors in the form of a prolonged absence of precipitation, combined with high temperature and a decrease in air humidity, leading to a violation of the water balance of plants and causing their inhibition or death.

Severe frost and heat are dangerous for the life and health of people, adversely affect their ability to work, and damage agriculture and industry. Also during such periods, the fire hazard increases. Long-term and extreme low temperatures pose a particular danger to public utilities due to freezing of water supply pipes on the streets and in buildings, which leads to a lack of water supply and water heating in people's homes.

High and low temperatures can be accompanied by strong winds. In winter, blizzards are dangerous. heavy blizzard- this is the transfer of snow above the ground by wind at a speed of more than 15 m / s and visibility of less than 500 m. A snowstorm is possible in combination with snowfall, which leads to a deterioration in visibility and skidding of transport routes.

In winter, the effect of the cooling force of the wind on the human body should be taken into account (Table 8.3).

In strong snowstorms and low temperatures, it is undesirable to move outside settlements. You can lose your bearings and freeze. The car can only move on major roads and highways. When leaving the car, do not leave it out of sight.

Table 8.3

The influence of the cooling force of the wind on the human body

Wind force, m/s

Temperature, °С

temperate zone

Growing danger zone

Dangerous zone

Meteorological phenomena associated with precipitation include the following.

Grad - atmospheric precipitation falling in the warm season in the form of particles of dense ice with a diameter of 5 mm to 15 cm, usually together with heavy rain during a thunderstorm. Large hail is considered to be ice particles with a diameter of more than 20 mm. Strong hail is dangerous to human life and health, it can destroy crops, damage the roofs of buildings and vehicles.

Downpour (heavy rain)- this is short-term precipitation of great intensity, usually in the form of rain (rain with snow). Heavy rain is considered to be precipitation of 50 mm or more in 12 hours or 30 mm or more in 1 hour. Prolonged heavy showers are precipitation of 100 mm or more in 2 days. Heavy rains can cause floods, flooding of streets, mudflows, and impede traffic.

Heavy snowfall - this is a prolonged intensive snowfall (20 mm of precipitation or more in 12 hours), leading to a significant deterioration in visibility and difficulty in traffic.

Meteorological phenomena associated with the formation of ice and sticking of wet snow to electrical wires pose a danger to power supply, which can lead to wire breaks and disruption of power supply to settlements and regions. Such cases happen in Russia, in particular, on the Black Sea coast of the Caucasus, in the Stavropol Territory, etc. Broken wires pose a danger to human life.

Ice- this is a layer of dense ice that forms on the earth's surface and on objects when supercooled drops of rain or fog (melted and then refrozen snow) freeze. Ice is dangerous for pedestrians and vehicles.

If the weather forecast indicates ice or icy conditions, measures should be taken to reduce the likelihood of injury, prepare low-slip shoes, attach metal heels or foam rubber to the heels, and stick adhesive plaster on dry soles, you can rub the soles of shoes with sandpaper.

You should move carefully, slowly, stepping on the entire sole. In this case, the legs should be slightly relaxed, hands free. If you slip, you should

crouch to reduce the height of the fall. At the time of the fall, it is necessary to group up, and, rolling, soften the blow to the ground.

Fog - meteorological phenomenon, the accumulation of condensation products in the form of drops or crystals suspended in the air directly above the surface of the earth, accompanied by a significant deterioration in visibility. Heavy fog is fog with a visibility of less than 100 m. Due to heavy fog, car accidents can occur, and airplanes cannot land at airports.