What causes various natural phenomena. Lesson summary on life safety: "Various natural phenomena and the reasons for their occurrence

29.09.2013 17391 0

The purpose of the lesson.Study the shells of the Earth and the processes occurring in the shells, as well as various natural phenomena that affect human safety. To acquaint students with the main natural phenomena of geological, meteorological, hydrological, biological and cosmic origin, to explain the main reasons for their occurrence.

Questions studied

1. The shells of the Earth.

2. The causes of various natural appear nium in the shells of the Earth.

3. The main natural phenomena according to the place of their occurrence.

4. Natural phenomena of geological origin.

5. Natural phenomena of meteorological and hydrological origin.

6. Natural phenomena of biological origin.

Presentation of educational material

1. When studying the first question, it is necessary to draw on information from geography. Shells or spheres of the Earth: core, lithosphere, atmosphere, biosphere

2. Continue the study of the Earth's shells, considering the cycles and movements of the earth's crust (in the lithosphere), in the atmosphere, water cycles and cycles in the biosphere (biological cycles).

All these processes characterize the life of our planet. V process of its development and are accompanied by various natural phenomena that have an impact significant influence on the safety of human life.

3. Natural phenomena are divided according to the place of their occurrence:

geological (earthquakes, volcanic eruptions, landslides, landslides and avalanches);

meteorological (hurricanes, storms, tornadoes);

hydrological (floods, mudflows, tsunamis);

biological (forest and peat fires, epidemics, epizootics, epiphytoties);

space.

In conclusion of the lesson, it should be noted that more than 30 types of hazardous natural phenomena are observed on the territory of Russia. The most destructive of them are: floods, earthquakes, landslides, mudflows, avalanches, hurricanes, storm winds, tornadoes and other natural phenomena.

A fifth of the territory of the Russian Federation is occupied by seismic hazard zones (areas where there is a danger of earthquakes).

One of the most frequently recurring natural disasters is floods. In Russia, a territory with a total area of ​​400 thousand square meters is subject to flooding. km. About 50 thousand square meters are flooded annually. km.

Difficult fire conditions constantly develop in the forests of the Russian Federation in the summer months.

4. Draw students’ attention to the fact that the earth’s crust, together with part of the upper mantle, is not a monolithic shell of the planet, but consists of several large blocks (plates) with a thickness of 60 to 100 km. In total there are 7 huge slabs and dozens of smaller slabs. Most plates form the basis of both continental and oceanic earth's crust, i.e. on these plates there are continents, seas and oceans.

The plates lie on a relatively soft, plastic layer of the upper mantle, along which they slowly move at a speed of 1 to 6 cm per year. Neighboring plates move closer together, diverge, or slide relative to each other. They float on the surface of the upper mantle, like pieces of ice on the surface of water.

As a result of the movement of plates, complex processes constantly occur in the bowels of the Earth. If two plates of the continental crust come together, their edges, together with all the sedimentary rocks accumulated on them, close into folds, forming mountain ranges, and with the onset of critical overloads they shift and tear. Breakups happen

instantly, accompanied by a jolt or a series of jolts that have the nature of blows. The energy released during the rupture is transmitted through the earth's crust in the form of elastic seismic waves and leads to earthquakes.

The boundary areas between lithospheric plates are called seismic belts. These are the most restless moving areas of the planet. The majority of active volcanoes are concentrated here and at least 95% of all earthquakes occur.

Thus, geological natural phenomena are associated with the movement and changes occurring in the lithosphere. Dangerous geological natural phenomena include earthquakes, volcanic eruptions, landslides, landslides and avalanches.

5. Characterize natural phenomena of a meteorological and hydrological nature and show their relationship

Meteorological natural phenomena are associated with various atmospheric processes, and primarily with processes occurring in the lower layer of the atmosphere - in the troposphere. The troposphere contains about 9/10 of the total air mass. Under the influence of solar heat entering the earth's surface, the rotation of the Earth around its axis and the force of gravity, the air in the troposphere moves in horizontal and vertical directions. Strongly heated air near the equator expands, becomes lighter and rises. Happening upward movement air. For this reason, low pressure forms at the Earth's surface near the equator. At the poles due to low temperatures the air cools, becomes heavier and sinks. There is a downward movement of air. For this reason, the pressure at the Earth's surface near the poles is high.

The movement of air masses and their interaction determine the weather in the places where these air masses arrive. The interaction of various air masses leads to the formation of giant vortices in the troposphere - cyclones and anticyclones.

A cyclone is an area of ​​low pressure in the atmosphere with a minimum in the center. The diameter of the cyclone is several thousand kilometers. The weather during a cyclone is predominantly cloudy with strong winds.

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

The movement of air masses and their interaction is associated with the emergence of dangerous meteorological phenomena, which may cause natural disasters. These are typhoons and hurricanes, storms, blizzards, tornadoes, thunderstorms, droughts, severe frosts and fogs.

Water on Earth is found in oceans and seas, in rivers and lakes, in the atmosphere in a gaseous state and in glaciers in a solid state.

All water on Earth that is not part of rocks is united by the concept of “hydrosphere”. The weight of all the water on Earth is so great that it is measured not in kilograms or tons, but in cubic kilometers. A cubic kilometer is a cube with each edge measuring 1 km, completely filled with water. The weight of 1 km 3 of water is equal to 1 billion tons. The Earth contains 1.5 billion km 3 of water, 97% of which is the World Ocean. Currently, it is customary to divide the World Ocean into 4 separate oceans and 75 seas with bays and straits.

Water is in a constant cycle, and closely interacts with the air shell of the Earth and with the land.

The driving force behind the water cycle is solar energy and gravity.

Under the influence sun rays water evaporates from the surface of the ocean and land (from rivers, reservoirs, soil and plants) and enters the atmosphere. Some of the water immediately returns with rain back to the ocean, while some is carried by winds to land, where it falls in the form of rain or snow. Once on the soil, water is partially absorbed into it, replenishing soil moisture reserves and groundwater, and partly flows into rivers and reservoirs. Soil moisture not only passes into plants, which evaporate it into the atmosphere, but also flows into rivers. Rivers, fed by surface streams and groundwater, carry water to the oceans, replenishing its loss. Water, evaporating from the surface of the World Ocean, again ends up in the atmosphere, and the cycle closes.

This movement of water between all components of nature and all parts of the earth's surface occurs constantly and uninterruptedly for many millions of years.

In the process of the water cycle in nature, dangerous natural phenomena constantly arise that affect the safety of human life and can lead to catastrophic consequences.

Hazardous natural phenomena of a hydrological nature include floods, tsunamis and mudflows.

6. Indicate that living organisms, including humans, interact with each other and the surrounding inanimate nature. During this interaction, the exchange of substances and energy occurs, continuous reproduction, growth of living organisms and their movement occur.

Among the most dangerous natural phenomena of a biological nature that have a significant impact on the safety of human life are:

natural fires;

epidemics;

epizootics;

epiphytoty.

At the end of the lesson, it is advisable to introduce students to

major space hazards.

The Earth is a cosmic body, a small particle of the Universe. Other cosmic bodies can have a strong influence on earthly life.

Everyone has seen “shooting stars” appear and disappear in the night sky. This meteors- small celestial bodies. We are observing a short-term flash of hot glowing gas in the atmosphere at an altitude of 70-125 km. It occurs when a meteor high speed invades the atmosphere.

If, during its movement in the atmosphere, the solid particles of the meteor do not have time to completely collapse and burn, then their remains fall to the Earth. This meteorites.

There are also larger celestial bodies that planet Earth can encounter. These are comets and asteroids.

Comets- these are bodies of the Solar system that quickly move in the starry sky, moving in highly elongated orbits. As they approach the Sun they begin to glow And they have a “head” and a “tail”. The central part of the “head” is called the nucleus. The diameter of the core can be from 0.5 to 20 km. The core is an icy body of frozen gases and dust particles. The “tail” of a comet consists of gas molecules and dust particles evaporated from the nucleus under the influence of the sun; rays. The length of the “tail” can reach tens of millions of kilometers.

Asteroids- these are small planets, the diameter of which ranges from 1 to 1000 km.

Currently, about 300 cosmic bodies are known that can cross the Earth's orbit. In total, according to astronomers, there are approximately 300 thousand asteroids and comets in space. The meeting of our planet with large celestial bodies poses a serious threat to the entire biosphere.

Control questions

1. What shells does planet Earth consist of?

2. What causes give rise to various natural phenomena on Earth?

3. What natural phenomena influence human safety?

4. What natural phenomena of geological origin most often occur on Earth?

5. What natural phenomena of meteorological and hydrological origin pose a danger to human life?

6. What hazardous natural phenomena are classified as natural phenomena of biological origin?

Homework

1. Study § 1.1, 1.2 of the textbook.

2. Highlight the natural phenomena that are most characteristic of your area. Describe the most dangerous for the population and the environment natural environment consequences of natural phenomena that have occurred in your region.

Significant difficulties in human life and activity are associated with natural phenomena. Natural disasters usually mean unexpected disruptions in the normal course of natural processes that have terrible consequences for humans.

Types of natural natural phenomena very diverse. These are earthquakes and volcanic eruptions, tsunamis and floods, showers and hurricanes, droughts and heavy snowfalls, mudflows and landslides, avalanches and more. They often cause superstitious fear in people and affect faith in supernatural forces.

In order to understand and explain the causes of various natural phenomena, it is necessary to know the laws of development of shells. Thus, volcanic eruptions, earthquakes and tsunamis are caused by geological processes occurring in the depths of the earth's crust. In the formation of hurricanes and tornadoes, the processes of energy and water exchange between the atmosphere and the ocean play a decisive role.

More than half of the world's natural disasters are associated with a catastrophic excess or lack of water (40% of all natural disasters are floods and 15% are droughts). The consequences of natural phenomena are especially severe when they occur simultaneously. The following diagram shows the relationship between natural phenomena in the lithosphere, hydrosphere and atmosphere.

Lithosphere Hydrosphere Atmosphere

Avalanches Hurricanes

Mudflows Floods Showers

Landslides Droughts

Landfalls Tornadoes

Earthquakes Tsunamis Frosts

Volcanic eruptions

High in the mountains, on the slopes of snow-capped peaks, white dragons lurk. They sleep quietly in the cold rocky beds. Their heads hang over valleys and abysses, and their tails in the form of long snow trails rise high up the gorges and ravines that furrow the harsh faces of the mountains.

Snow blizzards and storms rage over the lairs of monsters for days and weeks. Driven by angry winds. Heavy dark clouds are rushing by. They generously sprinkle snow on the mountain slopes and pile up huge snowdrifts.

It seems that neither the frantic dancing of whirlwinds, nor the whistle of the wind, nor the roar of hurricanes can interrupt the sleep of white dragons. But their lives are short-lived: some live for several months, while others only live for weeks or even days.

As if tired from a short nap, dragons fall from a height and fall, somersaulting, along steep slopes and raising clouds of snow dust. In a rapid run, they sweep away and destroy everything in their path.

U various peoples This formidable natural phenomenon is called differently. Residents of the Austrian Tyrol use the following words: “lai”, “laan”, “schneelaanen”, “lenen”. The French most often use the name "avalanche", and the Italians - "valanga". Our common name is “avalanche”.

The enormous speed of an avalanche, often reaching 100-120 and even 300 kilometers per hour, and a gigantic shock air wave, can turn stone buildings into ruins in a few seconds, tear off and scatter rock fragments, make wide gaps in a centuries-old forest, destroy all living things, falling within their scope of action.

A lot of snow accumulates in depressions on the mountain slopes. Often, after a thaw, the snow surface becomes covered with a crust of ice. But the end of winter is still far away; the snow continues to fall, and a loose, fluffy cover grows above the crust.

There comes a point when the top of the snow “pie” becomes so overloaded that even a tiny portion of snow can upset the balance and cause a collapse.

A small shock caused by wind or sound is enough for the entire mass, which is not at all connected with the lower, compacted layer, to move and begin to slide along the ice crust, as if on a sled. After just a few moments, its speed increases sharply and soon reaches the speed of a courier train. A silvery snow cloud rises high above her, and ahead, like a battering ram, an air wave moves.

This is how a dry, dusty, or wind avalanche arises, consisting of dry, loose snow.

It happens that heavy snowfall occurs during a thaw. Then fresh layers of heavy wet snow fall on top of the previously fallen snow. From the upper mass, water seeps down, wets the lower layers and moistens the surface of the underlying rocks. Because of this very water lubrication, the adhesion forces between snow and soil weaken, and the snow mass begins to slide down the slope. And since the snow is wet, there is no cloud above such a wet avalanche.

If in a dry avalanche a person is in danger of death from suffocation, then, if caught in a wet avalanche, he can be crushed or walled up with “snow cement”. The snow squeezes a person so tightly that he cannot move his arm or leg. The chances of survival are one in a million.

Great, oh how great is the amount of snow that comes down from the mountain slopes in avalanches!

How much snow is dumped by individual avalanches? The range is very large. The volume of small avalanches is hundreds, and large ones are tens of thousands and millions of cubic meters.

There are cases when quiet and harmless-looking kurums turn into a kind of water-mud-stone flows, the so-called mudflows - a formidable natural phenomenon that causes disasters to the local population.

In the mountains there are often heavy rains. They fill river beds with water, melt high-mountain snow, and cause glaciers to rapidly melt. And then, in addition to abundant rainwater, the rivers receive large amounts of melted snow and glacial water. This causes them to swell, become high-water, turbulent and ready to transport huge amounts of solid material from place to place.

This is where the revived kurums throw this material at them. Stormwater penetrates through the pile of stones to the clay layer and makes it slippery. Stone screes begin to slide along it, sliding down the slope - often they develop a speed of several meters per second.

And now the mudflow, which originated high in the mountains, begins a rapid march along the bottom of a steeply falling mountain gorge. Capturing ever new masses of stone fragments, it becomes so strong and powerful that it easily moves large boulders along the way and rolls boulders the size of a haystack and even a house.

Mudflows usually come in torrents. Having stumbled upon an obstacle, he stops, but not for long. New masses of water and mud push, the shaft grows, the jam breaks through, and an even heavier, powerful mud-stone avalanche takes off, rushes down, crushing everything that comes in its way. It happens that a mudflow consists of half water, and the rest is dirt and stones. But this doesn’t make it any easier. Mudflows of enormous size travel tens of kilometers and carry hundreds of thousands and even millions of cubic meters of solid material out of the mountains.

Mudflows occur in the mountains of the Caucasus, Asia, Siberia, Far East, in the Alps, Carpathians, Cordillera and many other areas globe. The Swiss call them "ruff", the French - "vant", the Germans - "mur".

Landslides are the movement of rock masses down a slope under the influence of gravity. The condition for the formation of a landslide is the occurrence of an aquifer layer close to the surface and waterlogged upper layers. They slide over a layer of clay (aquitard). If there is a house on the body of the landslide, it will slide down and collapse. A landslide can destroy a village and cover a road.

Landslides occur on less steep slopes. Their movement occurs smoothly, calmly over hours, days and even months.

River water that has seeped deep into the earth's crust has a treacherous effect. It impregnates layers of loose sediments and moisturizes clays. Often such a moistened layer plays the role of a lubricant between the layers of the earth, and the upper layer, as if on a sled, begins to slide and float down. Small landslides are called “slides”.

Landslides in the CIS most often occur in the Volga region, along the right bank of the Lower Dnieper, on Black Sea coast in the Odessa region, in some points of the Southern Crimea, the Caucasus, in coastal zone Baikal.

Landslides in the Nizhny Novgorod region and the damage they cause have been known for a long time. This is even written about in ancient chronicles. In the 15th century, a landslide descended from Gremyachaya Mountain, destroying a large settlement. The chronicle reports: “And by God’s will of sins, for the sake of our sins, the mountain crawled from above the settlement, and one hundred and fifty households with people and all kinds of livestock fell asleep in the settlement.”

The disaster that happened at the end of the 16th century was reported: “in Nizhny Novgorod, the earth under the monastery shook, and the monks fled and stash on the mountains; the monastery and churches completely perished. In the same Nizhny Novgorod, up the Oka River, a settlement of 150 households perished completely into the ground, and not a person remained.”

In more late period One of the largest landslides occurred on the night of June 17, 1839 in the area of ​​the village of Fedorovka on the left bank of the Volga between Saratov and Ulyanovsk.

The earth moved underfoot, houses cracked and shook, there was noise and roar in the air. Nobody understood what happened. People didn't know where to run. Women and children screamed loudly and cried. Dawn came, but nothing changed.

Suddenly the ground began to shake more strongly. In some places it swelled and instead of lowlands, hills grew, and in place of hills there were gaps and cracks.

The vibrations of the earth's surface, sometimes stronger, sometimes weaker, lasted for three days.

Everything stopped suddenly. 70 houses were destroyed or damaged. Fortunately, there were no casualties. Later it turned out that the village had moved several tens of meters closer to the Volga!

Sometimes certain areas of the area coastal strip“move out” very slowly and gradually. Trouble then comes unnoticed. The writer V. Chelintsev described the consequences of a slowly sliding area near the city of Volsk in 1902: “There is a house in front of you; you look: a house is like a house; but now you go out into the yard; the back half of the house in question seemed not to be his, but was only clumsily and bizarrely attached to it, as if from a completely different house, the corner closest to us was closed somehow askew: the house seemed to have grown old and, like an old man on his stick, leaned on this corner so that not to let their houses and outbuildings perish, the inhabitants of this lowland constantly have to fight the landslide and win their place from it as persistently as the Dutch win their place from the sea.”

Earthquakes

Earthquakes, based on the reasons for their occurrence, are divided into meteorite, volcanic and tectonic, that is, caused by the internal development of the Earth. Meteor earthquakes are caused by celestial bodies falling onto the earth's surface. Humanity practically does not remember such disasters, but there is no doubt that they played a role in the history of the Earth, and this still needs to be studied geological observations. Volcanic earthquakes have occurred and occur quite often; they can reach high intensity - up to 8-10 points and cause significant disasters. But the destructive waves of these earthquakes do not spread far to the sides, since their seismic foci lie at shallow depths. The most common and powerful are tectonic earthquakes; They are associated with catastrophic destruction of buildings and redrawing of the face of the Earth.

When and why do tectonic earthquakes occur?

Under the influence of deep tectonic forces, layers of rocks are deformed, crushed into folds and, with the onset of critical overloads, break, forming faults in the earth's crust. It is at this moment that an instantaneous shock or series of shocks occurs, like blows. During an earthquake, energy accumulated in the depths is released. The energy released at depth, at the rupture point - at the hypocenter or focus (focus) of the earthquake, is transmitted through elastic waves the earth's crust and reaches the surface of the Earth, where it causes destruction.

The greatest destruction is concentrated on a small area of ​​the earth's surface, which is called the epicenter of the earthquake.

All observations of the intensity of earthquakes, determination of the size of soil displacements, study of rock deformation and other physical phenomena caused by earthquakes are carried out by scientists at the epicenters, that is, on the surface of the Earth. And the accumulation and release of stress leading to an earthquake occurs inside the earth’s crust, which reaches a thickness of several tens of kilometers.

The danger of earthquakes is not universal, but is tied to narrow zones of tectonic faults and depends on deep stresses.

The element appears where one or another fault is more active. This means that living there is the most dangerous place. But it is known that catastrophic earthquakes on the same fault, even in active zones, are rarely repeated: deep stresses must accumulate and gather into a powerful clot of energy capable of producing a crushing blow.

The surface of the Earth is continuously attacked by deep seismic tremors. Over 100 thousand earthquakes occur during the year. In other words, every 5 minutes there is at least one underground shock: the Earth seems to be constantly trembling. Most tremors are weak, they are not felt by people and are recorded only by highly sensitive instruments - seismographs. But every year about ten earthquakes reach destructive force, and isolated, especially strong ones, acquire the character of severe disasters.

According to statistics, 10 thousand people die from earthquakes in the world every year. During particularly severe disasters, the number of victims is measured in many tens and even hundreds of thousands of people. The damage caused by earthquakes is measured not only by the number of victims. During catastrophic earthquakes, cracks form along which blocks of the earth's crust move, new hills and dips appear, the direction of rivers changes, and almost all artificial structures and buildings are destroyed. Everyone remembers the catastrophic earthquakes of recent years; they brought severe disasters to densely populated areas. Earthquakes great strength destroyed Ashgabat, Tashkent, populated areas of Turkmenistan, Tajikistan, Armenia, Dagestan, Moldova, and swept away the village of Neftegorsk on Sakhalin.

Subject: General concepts about dangerous and emergency situations natural character.

Lesson topic: Natural phenomena and their classification.

The purpose of the lesson: To introduce students to natural phenomena and their diversity.

Lesson objectives:

I. Educational objectives:

• Recall and consolidate knowledge about the shells of the Earth.
• To develop students’ knowledge that the formation of any natural phenomenon is associated with processes occurring in the Earth’s shells.
• Give general idea, students about the types of natural phenomena at the place of their occurrence.

II. Developmental tasks.

• To develop in students the ability and ability to foresee natural phenomena in their area that can lead to serious consequences, as well as ways to protect against them.

III. Educational tasks.

• To instill in students the conviction that any natural phenomenon of destructive force brings enormous damage of various types to the state, primarily material and loss of life. Therefore, the state needs to allocate funds to scientific institutions so that they can deal with this problem and be able to predict them in the future.

During the classes

Teacher: Today, children, we will talk about natural phenomena and their diversity. Some you know, of course, some you learned from a course in natural history and geography, and if anyone is interested in the means mass media then from there. If you turn on the TV, radio or use the Internet, you can say with confidence that natural phenomena of destructive force are occurring more and more often, and their strength is becoming greater. Therefore, we need to know what natural phenomena occur, where they most often occur and how to protect ourselves from them.

Teacher: And so let's remember from the geography course what shells of the Earth exist.

In total, there are 4 shells of the Earth:

1. Lithosphere - it includes the earth's crust and the upper part of the mantle.
2. Hydrosphere – water shell, it includes all water in different states.
3. The atmosphere is a gas shell, the lightest and most mobile.
4. The biosphere is the sphere of life, this is the area of ​​existence of all living organisms.

Teacher: All these shells have their own specific processes, as a result of which natural phenomena arise. Therefore, various natural phenomena can be divided according to the place of their occurrence:

Teacher: From this diagram we see how many natural phenomena there are. Now let's look at each of them and find out what they are. (Children must take an active part in this part.)

Geological.

1. An earthquake is a natural phenomenon associated with geological processes occurring in the Earth’s lithosphere; it manifests itself in the form of tremors and vibrations of the earth’s surface, resulting from sudden displacements and ruptures in the earth’s crust or in the upper part of the mantle.

Picture 1.

2. A volcano is a conical mountain from which hot material – magma – erupts from time to time.

A volcanic eruption is the release of molten matter from the Earth’s crust and mantle, called magma, onto the surface of the planet.

Figure 2.

3. A landslide is a sliding downward displacement of soil masses under the influence of gravity, which occurs on slopes when the stability of the soil or rocks is disrupted.

The formation of landslides depends on various factors, such as:

• what rocks make up this slope;
• slope steepness;
• groundwater and etc.

Landslides can occur as naturally(for example, an earthquake, heavy rainfall), and artificially (for example, human activities: deforestation, soil excavation).

Figure 3.

4. A landslide is the separation and fall of large masses of rocks, their overturning, crushing and rolling down on steep and steep slopes.

Causes of landslides in mountains can be:

• the rocks that make up the mountains are layered or broken by cracks;
• water activity;
• geological processes(earthquake), etc.

The causes of landslides on the coasts of seas and rivers are the erosion and dissolution of underlying rocks.

Figure 4.

5. A snow avalanche is a collapse of a mass of snow on mountain slopes; the angle of inclination must be at least 15°.

The causes of an avalanche are:

• earthquake;
• intense snow melting;
• prolonged snowfall;
• human activity.

Figure 5.

Meteorological.

1. A hurricane is a wind whose speed exceeds 30 m/s, leading to enormous destruction.

Figure 6.

2. A storm is wind, but at a lower speed than in a hurricane and is no more than 20 m/s.

Figure 7.

3. Tornado – represents atmospheric vortex, formed in a thundercloud and descending, has the shape of a funnel or sleeve.

A tornado consists of a core and a wall. There is an upward movement of air around the core, the speed of which can reach 200 m/s.

Figure 8.

Hydrological.

1. Flood is a significant inundation of an area as a result of rising water levels in a lake, river, etc.

Causes of flooding:

• intensive snow melting in spring;
• heavy rainfall;
• obstruction of river beds with rocks during an earthquake, landslide, etc., as well as with ice during congestion;
• wind activity (water surge from the sea, bay to the mouth of the river).

Types of floods:

Figure 9.

2. Mudflow is a stormy stream in the mountains that is temporary in nature, consisting of water and large quantity rock fragments.

The formation of mudflows is associated with heavy precipitation in the form of rain or intense snow melting. As a result, loose rocks are washed away and move along the river bed at high speed, which picks up everything in its path: boulders, trees, etc.

Figure 10.

3. Tsunami is a type sea ​​waves, resulting from vertical displacement of significant areas of the seabed.

A tsunami occurs as a result of:

• earthquakes;
• underwater volcanic eruptions;
• landslides, etc.

Figure 11.

Biological.

1. A forest fire is an uncontrolled burning of vegetation that spontaneously spreads through a forest area.

A forest fire can be ground fire or crown fire.

An underground fire is the burning of peat in marshy and swampy soils.

Figure 12.

2. An epidemic is the spread of an infectious disease among a large population and significantly exceeds the incidence rate usually recorded in a given area.

Figure 13.

3. Epizootic is a widespread infectious disease among animals (for example: foot and mouth disease, swine fever, cattle brucellosis).

Figure 14.

4. Epiphytoty is a mass distribution infectious disease among plants (for example: late blight, wheat rust).

Figure 15.

Teacher: As you can see, in the world there are a huge number of phenomena that surround us. So let's remember them and be extremely careful when they occur.

Some of you may say: “Why do we need to know all of them if most of them are not typical for our area?” From one point of view you are right, but from another you are wrong. Each of you tomorrow, the day after tomorrow or in the future will probably be going on a trip to other parts of the Motherland and the country. And there, as we know, there may be completely different phenomena that are not typical for our area. And then your knowledge will help you survive in a critical situation and avoid negative consequences. As they say: “God protects those who are careful.”

Literature.

1. Smirnov A.T. Fundamentals of life safety. 7th grade.
2. Shemanaev V.A. Teaching practice in the system of training a modern teacher.
3. Smirnov A.T. Program of general education institutions basics of life safety for grades 5-11.

Natural phenomena are ordinary, sometimes even supernatural, climatic and meteorological events that occur naturally in all corners of the planet. It could be snow or rain, familiar from childhood, or it could be incredibly destructive or earthquakes. If such events take place away from a person and do not cause him material damage, they are considered unimportant. Nobody will pay attention to this. Otherwise, dangerous natural phenomena are considered by humanity as natural disasters.

Research and observations

People began to study characteristic natural phenomena in ancient times. However, it was possible to systematize these observations only in the 17th century; even a separate branch of science (natural science) was formed that studied these events. However, despite many scientific discoveries, and to this day some natural phenomena and processes remain poorly understood. Most often, we see the consequence of this or that event, but we can only guess about the root causes and build various theories. Researchers in many countries are working to make forecasts of their occurrence, and most importantly, to prevent their possible occurrence or at least reduce the damage caused by natural phenomena. And yet, despite all the destructive power of such processes, a person always remains a person and strives to find something beautiful and sublime in this. What natural phenomenon is most fascinating? They could be listed for a long time, but perhaps it should be noted such as a volcanic eruption, a tornado, a tsunami - they are all beautiful, despite the destruction and chaos that remain after them.

Weather phenomena of nature

Natural phenomena characterize the weather with its seasonal changes. Each season has its own set of events. For example, in the spring the following snowmelt, floods, thunderstorms, clouds, wind, and rain are observed. IN summer period the sun gives the planet an abundance of heat, natural processes at this time are most favorable: clouds, warm winds, rains and, of course, rainbows; but they can also be severe: thunderstorms, hail. In autumn the temperature changes, the days become cloudy and rainy. During this period, the following phenomena prevail: fog, leaf fall, frost, first snow. in winter vegetable world falls asleep, some animals hibernate. The most common natural phenomena are: freeze-up, blizzard, blizzard, snow, which appear on the windows

All these events are commonplace for us; we have not paid attention to them for a long time. Now let's look at the processes that remind humanity that it is not the crown of everything, and planet Earth just sheltered it for a while.

Natural hazards

These are extreme and severe climate and meteorological events that occur in all parts of the world, but some regions are considered more vulnerable to certain types of events compared to others. Natural hazards become disasters when infrastructure is destroyed and people die. These losses represent major obstacles to human development. It is almost impossible to prevent such cataclysms; all that remains is timely forecasting of events in order to prevent casualties and material damage.

However, the difficulty lies in the fact that dangerous natural phenomena can occur on different scales and in different time. In fact, each of them is unique in its own way, and therefore it is very difficult to predict it. For example, flash floods and tornadoes are destructive but short-lived events that affect relatively small areas. Other dangerous disasters, such as droughts, can develop very slowly but affect entire continents and entire populations. Such disasters last for several months and sometimes years. In order to monitor and predict these events, some national hydrological and meteorological services and special specialized centers are tasked with studying hazardous geophysical phenomena. This includes volcanic eruptions, airborne ash, tsunamis, radioactive, biological, chemical pollution, etc.

Now let's take a closer look at some natural phenomena.

Drought

The main reason for this cataclysm is the lack of precipitation. Drought is very different from other natural disasters in its slow development, often its onset is hidden by various factors. There are even recorded cases in world history when this disaster lasted for many years. Drought often has dire consequences: first, water sources (streams, rivers, lakes, springs) dry up, many crops stop growing, then animals die, becoming widespread realities. poor health and malnutrition.

Tropical cyclones

These natural phenomena represent areas of very low atmospheric pressure over subtropical and tropical waters, forming a colossal rotating system of thunderstorms and winds hundreds (sometimes thousands) of kilometers across. The speed of surface winds in the zone of a tropical cyclone can reach two hundred kilometers per hour or even more. Interaction low pressure and wind-driven waves often result in a coastal storm surge - a huge volume of water thrown ashore with tremendous force and high speed, which wash away everything in their path.

Air pollution

These natural phenomena arise as a result of the accumulation in the air of harmful gases or particles of substances formed as a result of disasters (volcanic eruptions, fires) and human activities (the work of industrial enterprises, vehicles, etc.). Haze and smoke result from fires in undeveloped lands and forested areas, as well as the burning of crop residues and logging; in addition, due to the formation of volcanic ash. These air pollutants have very serious consequences for the human body. As a result of such disasters, visibility is reduced and interruptions in the operation of road and air transport occur.

Desert Locust

Similar natural phenomena cause serious damage in Asia, the Middle East, Africa and southern European continent. When environmental and weather conditions are favorable for the reproduction of these insects, they tend to concentrate in small areas. However, as their numbers increase, the locust ceases to be an individual creature and turns into a single living organism. Small groups form huge flocks that move in search of food. The length of such a school can reach tens of kilometers. In a day, it can cover distances of up to two hundred kilometers, sweeping away all vegetation in its path. So, one ton of locusts (this is a small part of the swarm) can eat as much food in a day as ten elephants or 2,500 people eat. These insects pose a threat to millions of pastoralists and farmers living in vulnerable environmental conditions.

Flash floods and flash floods

Data can occur anywhere after heavy rainfall. All floodplains are vulnerable to flooding, and severe storms cause flash floods. In addition, short-term floods sometimes even occur after periods of drought, when very heavy rain falls on a hard and dry surface through which water flow cannot seep into the ground. These natural events are characterized by a wide variety of types: from violent small floods to a powerful layer of water that covers vast areas. They can be caused by tornadoes, severe thunderstorms, monsoons, extratropical and tropical cyclones (their strength may be increased by exposure to warm weather). El Niño currents), melting snow and ice jams. In coastal areas, storm surges often lead to flooding as a result of a tsunami, cyclone, or rising river levels due to unusually high tides. The reason for the flooding of vast areas located below the barrier dams is often high water on rivers, which is caused by melting snow.

Other natural hazards

1. Mud flow or landslide.

5. Lightning.

6. Extreme temperatures.

7. Tornado.

10. Fires on undeveloped lands or forests.

11. Heavy snow and rain.

12. Strong winds.

Over the billions of years of our planet’s existence, certain mechanisms by which nature works have formed. Many of these mechanisms are subtle and harmless, while others are large-scale and cause enormous destruction. In this rating, we will talk about the 11 most destructive natural disasters on our planet, some of which can destroy thousands of people and an entire city in a few minutes.

11

A mudflow is a mud or mud-stone flow that suddenly forms in the beds of mountain rivers as a result of rainfall, rapid melting of glaciers or seasonal snow cover. The decisive factor in the occurrence may be deforestation in mountainous areas - tree roots hold top part soil, which prevents the occurrence of mudflows. This phenomenon is short-term and usually lasts from 1 to 3 hours, typical for small watercourses up to 25-30 kilometers long. Along their path, streams carve deep channels that are usually dry or contain small streams. The consequences of mudflows can be catastrophic.

Imagine that a mass of earth, silt, stones, snow, sand, driven by a strong flow of water, fell on the city from the mountains. This stream will demolish the dacha buildings located at the foot of the city along with the people, and orchards. This entire stream will rush into the city, turning its streets into raging rivers with steep banks of destroyed houses. Houses will be torn off their foundations and, along with their people, will be carried away by a stormy stream.

10

Landslide is the sliding of masses of rocks down a slope under the influence of gravity, often while maintaining their coherence and solidity. Landslides occur on the slopes of valleys or river banks, in the mountains, on the shores of the seas, and the largest ones occur at the bottom of the seas. The displacement of large masses of earth or rock along a slope is caused in most cases by wetting the soil with rainwater so that the soil mass becomes heavier and more mobile. Such large landslides damage agricultural land, businesses, settlements. To combat landslides, bank protection structures and planting of vegetation are used.

Only rapid landslides, the speed of which is several tens of kilometers, can cause real natural disasters with hundreds of casualties when there is no time for evacuation. Imagine that huge pieces of soil are quickly moving from a mountain directly onto a village or city, and under tons of this earth, buildings are destroyed and people who did not have time to leave the landslide site die.

9

A sandstorm is an atmospheric phenomenon in the form of transport large quantities dust, soil particles and grains of sand blown several meters from the ground with a noticeable deterioration in horizontal visibility. In this case, dust and sand rise into the air and at the same time dust settles over a large area. Depending on the color of the soil in a given region, distant objects take on a grayish, yellowish or reddish tint. It usually occurs when the soil surface is dry and the wind speed is 10 m/s or more.

Most often, these catastrophic phenomena occur in the desert. A sure sign that a sandstorm is starting is sudden silence. Rustles and sounds disappear with the wind. The desert literally freezes. A small cloud appears on the horizon, which quickly grows and turns into a black and purple cloud. The missing wind rises and very quickly reaches speeds of up to 150-200 km/h. A sandstorm can cover streets within a radius of several kilometers with sand and dust, but the main danger of sandstorms is the wind and poor visibility, which causes car crashes, in which dozens of people are injured, and some even die.

8

An avalanche is a mass of snow falling or sliding down the slopes of mountains. Snow avalanches pose a considerable danger, causing casualties among climbers, skiers and snowboarders and causing significant damage to property. Sometimes avalanches have catastrophic consequences, destroying entire villages and causing the death of dozens of people. Snow avalanches, to one degree or another, are common in all mountainous regions. IN winter period they are the main natural hazard of the mountains.

Tones of snow are held on top of mountains due to the force of friction. Large avalanches occur at the moment when the pressure force of the snow mass begins to exceed the force of friction. A snow avalanche is usually triggered by climatic reasons: sudden changes in weather, rain, heavy snowfalls, as well as mechanical effects on the snow mass, including the effects of rockfalls, earthquakes, etc. Sometimes an avalanche can begin due to a minor shock such as a weapon shot or pressure on the snow of a person. The volume of snow in an avalanche can reach several million cubic meters. However, even avalanches with a volume of about 5 m³ can be life-threatening.

7

A volcanic eruption is the process of a volcano throwing hot debris, ash, and magma onto the earth’s surface, which, when poured onto the surface, becomes lava. A major volcanic eruption can last from a few hours to many years. Hot clouds of ash and gases, capable of moving at speeds of hundreds of kilometers per hour and rising hundreds of meters into the air. The volcano emits gases, liquids and solids with high temperatures. This often causes the destruction of buildings and loss of life. Lava and other hot erupted substances flow down the slopes of the mountain and burn out everything they meet on their way, causing innumerable casualties and staggering material losses. The only protection against volcanoes is general evacuation, so the population must be familiar with the evacuation plan and unquestioningly obey the authorities if necessary.

It is worth noting that the danger from a volcanic eruption exists not only for the region around the mountain. Potentially, volcanoes threaten the lives of all life on Earth, so you shouldn’t be lenient towards these hot guys. Almost all manifestations of volcanic activity are dangerous. The danger of boiling lava goes without saying. But no less terrible is the ash, which penetrates literally everywhere in the form of continuous gray-black snowfall, which covers streets, ponds, and entire cities. Geophysicists say they are capable of eruptions hundreds of times more powerful than those ever observed. Major volcanic eruptions, however, have already occurred on Earth - long before the advent of civilization.

6

A tornado or tornado is an atmospheric vortex that arises in a thundercloud and spreads down, often to the very surface of the earth, in the form of a cloud arm or trunk with a diameter of tens and hundreds of meters. Typically, the diameter of a tornado funnel on land is 300-400 meters, but if a tornado occurs on the surface of water, this value can be only 20-30 meters, and when the funnel passes over land it can reach 1-3 kilometers. The largest number of tornadoes is recorded on the North American continent, especially in the central states of the United States. About a thousand tornadoes occur in the United States every year. The strongest tornadoes can last up to an hour or more. But most of them last no more than ten minutes.

On average, about 60 people die from tornadoes each year, mostly from flying or falling debris. However, it happens that huge tornadoes rushing at a speed of about 100 kilometers per hour, destroying all buildings in their path. The maximum recorded wind speed in the largest tornado is about 500 kilometers per hour. During such tornadoes, the death toll can number in the hundreds and the number of injured in the thousands, not to mention the material damage. The reasons for the formation of tornadoes have not yet been fully studied.

5

A hurricane or tropical cyclone is a type of low-pressure weather system that occurs over a warm sea surface and is accompanied by severe thunderstorms, heavy rainfall and gale-force winds. The term “tropical” refers to both the geographic area and the formation of these cyclones in tropical air masses. It is generally accepted, according to the Beaufort scale, that a storm becomes a hurricane when wind speeds exceed 117 km/h. The most strong hurricanes capable of causing not only extreme downpours, but also large waves on the sea surface, storm surges and tornadoes. Tropical cyclones can arise and maintain their strength only over the surface of large bodies of water, while over land they quickly lose strength.

A hurricane can cause heavy rain, tornadoes, small tsunamis and floods. The direct effect of tropical cyclones on land is stormy winds that can destroy buildings, bridges and other man-made structures. The strongest constant winds within the cyclone exceed 70 meters per second. The worst effect of tropical cyclones in terms of death toll historically has been storm surge, which is the rise in sea level caused by the cyclone, which on average accounts for about 90% of the casualties. Over the past two centuries, tropical cyclones have killed 1.9 million people worldwide. In addition to the direct effect on residential buildings and economic facilities, tropical cyclones destroy infrastructure, including roads, bridges, and power lines, causing enormous economic damage to the affected areas.

The most destructive and terrible hurricane in US history, Katrina, occurred at the end of August 2005. The heaviest damage was caused to New Orleans in Louisiana, where about 80% of the city's area was under water. As a result natural disaster 1,836 residents were killed and economic losses amounted to $125 billion.

4

Flood - flooding of an area as a result of rising water levels in rivers, lakes, seas due to rain, rapid snow melting, wind surge of water to the coast and other reasons, which damages people's health and even leads to their death, and also causes material damage . For example, in mid-January 2009, the largest flood in Brazil occurred. More than 60 cities were affected then. About 13 thousand people fled their homes, more than 800 people died. Floods and numerous landslides are caused by heavy rains.

Strong monsoon rains have continued in Southeast Asia since mid-July 2001, causing landslides and flooding in the Mekong River region. As a result, Thailand experienced its worst floods in the last half century. Streams of water flooded villages, ancient temples, farms and factories. At least 280 people died in Thailand, and another 200 in neighboring Cambodia. Some 8.2 million people in 60 of Thailand's 77 provinces have been affected by the floods, and economic losses so far are estimated to exceed $2 billion.

Drought - long period stable weather with high air temperatures and low precipitation, which results in a decrease in soil moisture reserves and the suppression and death of crops. The onset of severe drought is usually associated with the establishment of a sedentary high anticyclone. The abundance of solar heat and gradually decreasing air humidity create increased evaporation, and therefore the reserves of soil moisture are depleted without replenishment by rain. Gradually, as soil drought intensifies, ponds, rivers, lakes, and springs dry up—a hydrological drought begins.

For example, in Thailand, almost every year, severe floods alternate with severe droughts, when a state of emergency is declared in dozens of provinces, and several million people feel the effects of drought in one way or another. As for the victims of this natural phenomenon, in Africa alone, from 1970 to 2010, the death toll from droughts is 1 million people.

2

Tsunamis are long waves generated by a powerful impact on the entire thickness of water in the ocean or other body of water. Most tsunamis are caused by underwater earthquakes, during which a portion of the seabed suddenly shifts. Tsunamis are formed during an earthquake of any strength, but those that arise due to strong earthquakes with a magnitude of more than 7 on the Richter scale reach great strength. As a result of an earthquake, several waves are propagated. More than 80% of tsunamis occur on the periphery of the Pacific Ocean. The first scientific description of the phenomenon was given by José de Acosta in 1586 in Lima, Peru, after a powerful earthquake, then a strong tsunami 25 meters high burst onto land at a distance of 10 km.

The largest tsunamis in the world occurred in 2004 and 2011. So, on December 26, 2004 at 00:58, a powerful earthquake of magnitude 9.3 occurred - the second most powerful of all recorded, which caused the deadliest tsunami of all known. Asian countries and African Somalia were hit by the tsunami. Total the number of deaths exceeded 235 thousand people. The second tsunami occurred on March 11, 2011 in Japan after a strong earthquake of magnitude 9.0 with an epicenter caused a tsunami with a wave height exceeding 40 meters. In addition, the earthquake and subsequent tsunami caused the accident at the Fukushima I nuclear power plant. As of July 2, 2011, the official death toll from the earthquake and tsunami in Japan is 15,524 people, 7,130 people are missing, 5,393 people wounded.

1

An earthquake is an underground tremors and vibrations of the Earth's surface caused by natural causes. Small tremors can also be caused by the rise of lava during volcanic eruptions. About a million earthquakes occur throughout the Earth each year, but most are so small that they go unnoticed. The strongest earthquakes, capable of causing widespread destruction, occur on the planet approximately once every two weeks. Most of them fall on the bottom of the oceans and are therefore not accompanied by catastrophic consequences if an earthquake occurs without a tsunami.

Earthquakes are best known for the devastation they can cause. Destructions of buildings and structures are caused by soil vibrations or giant tidal waves (tsunamis) that occur during seismic displacements on the seabed. A powerful earthquake begins with the rupture and movement of rocks somewhere deep within the Earth. This location is called the earthquake focus or hypocenter. Its depth is usually no more than 100 km, but sometimes it reaches 700 km. Sometimes the source of an earthquake can be near the surface of the Earth. In such cases, if the earthquake is strong, bridges, roads, houses and other structures are torn and destroyed.

The largest natural disaster An earthquake of magnitude 8.2 is believed to have occurred on July 28, 1976 in the Chinese city of Tangshan, Hebei Province. According to official data from the PRC authorities, the death toll was 242,419 people, however, according to some estimates, the death toll reaches 800 thousand people. At 3:42 local time the city was destroyed strong earthquake. There was also destruction in Tianjin and Beijing, just 140 km to the west. As a result of the earthquake, about 5.3 million houses were destroyed or damaged so much that they were uninhabitable. Several aftershocks, the strongest of which had a magnitude of 7.1, led to even greater casualties. The Tangshan earthquake is the second largest in history after the devastating earthquake in Shaanxi in 1556. About 830 thousand people died then.