What is fire and combustion? Definition of fire. Natural fires (forest, peat): definition. Reduced oxygen concentration in the fire zone

Often ordinary people cannot distinguish a local fire from a global fire: in both cases there is fire, a lot of smoke, soot, fear and panic, the desire to extinguish the source of trouble as quickly as possible. All this is true. But it is still worth understanding the difference between fire and fire in order to promptly determine the degree of danger to surrounding people and property and take appropriate action. The first and second have their own characteristic features.

Definition

Fire- a disaster, including plumes of smoke, the spread of fire across adjacent areas. The rate of combustion depends on the materials consumed by the fire, as well as on the presence and direction of wind. In general, a fire is a global manifestation of the fire element, which can differ not only in the scale of what is happening, but also have several degrees of complexity. In the generally accepted classification, the fire category is calculated based on the location of the fire, the degree of difficulty of extinguishing, and the presence or absence of additional factors that increase the danger. Thus, we can conclude that fire is a complex disaster covering large areas and has its own classification.

Fire has a local location, is characterized by a small area coverage, the absence of significant spread of fire, smoke and threat to humans. To extinguish a fire, short-term measures are not always enough; everything can turn out to be several hours or even days. From a fire point of view, such a small flame can destroy ordinary person without any special skills. Sometimes just a glass of water or using some improvised means to put out the flame is enough. In general, a fire is a small source of flame that can be easily and quickly extinguished.

Comparison

Obvious differences strike the inquisitive reader even at the stage of defining these two concepts.

A fire is a disaster that can often only be eliminated by professional firefighters using specialized equipment. But anyone familiar with the basic rules of life safety can handle a fire.

A fire can vary in categories, which are calculated by taking into account many associated factors, while no one has ever classified a fire because it does not need to be. Usually it is just a small fireplace, not always with an open flame, but simply with smoke or smoldering that is easy to put out.

Conclusions website

1. A fire is a global manifestation of the fire element and can cause great damage, while a fire is local and insignificant in nature.
2. To extinguish a fire, professionals who have undergone special training are needed, while a fire can be handled by an ordinary person.
3. Fire has several categories, but there is no classification of fire.

Fires cause serious material damage and in some cases result in the death of people. Therefore, every reasonable member of our society should be able to defend against them. It is very important that the state contributes in every possible way to the dissemination of educational information on this topic. In this article we will tell you about the types of fires, as well as measures to prevent this process. So let's get started.

Concept

A fire is a combustion process that occurs involuntarily (or due to malicious intent) and continues until all flammable materials and substances are burned, or measures are taken to extinguish it, or conditions conducive to self-extinguishing appear.

Conditions of occurrence

A fire occurs when:

• Oxygen contained in the surrounding air.
• Fuel: furniture, clothes, bed linen, bottle of gasoline, etc.
• Heat source: electric heater, open flame, lit match.
• The person who causes most fires.

Fire classification

By external signs fires are divided into hidden, open, internal, external and simultaneously internal and external. Let's talk about each of them in more detail.

External

They take first place in the list of “fire classes”. They can be visually identified by combustion signs such as smoke and flames. Such fires occur when buildings, peat, coal and other fires ignite. material assets located on open storage areas; when burning petroleum products in tanks, on open racks and technological installations; grain crops, peat fields, forests, etc.

Domestic

They arise and develop exclusively inside buildings. They can be hidden or open.

Open

Signs of combustion in open fires can be determined by inspecting the premises. For example, burning of materials and equipment in production workshops, coatings, floors, partitions, etc.

Hidden

In hidden fires, the combustion process occurs in ventilation ducts and shafts, niches of building structures, and the internal layers of peat deposits. At the same time, smoke comes out of the cracks, the structures become very hot, and the color of the plaster changes. Fire may be visible when dismantling or opening structures and stacks.

As the situation changes, the classes of fires also change. For example, internal hidden combustion can develop into open combustion. Also, an internal fire can become an external fire, and vice versa.

Fires are also distinguished by their location. They occur in open storage areas, in structures, buildings and in combustible areas (peat, steppe, forest and grain fields).

In populated areas and industrial enterprises, fires can be individual (in a structure or building) and massive (a set of fires covering more than 90% of the building).

Types of fires

1. Fires in a home or building

The main reason for its occurrence is human inattention. Failure of electrical installations can lead to fire; inept and careless use of electrical appliances; spontaneous combustion of the TV, operation of homemade electric heaters and fuses, ineptly executed electrical wiring. And, of course, violation of the rules for operating a gas stove. Fire prevention, described below, will help to avoid fire.

2. Forest

Let's start with the definition. A forest fire is the uncontrolled, spontaneous spread of fire in a forest area. The causes can be anthropogenic or natural. But the most common cause of a forest fire is lightning. Fires can grow in size to such an extent that they can be seen from space.

There are ground and crown types of forest fires. Let's look at them in more detail.

Grassroots

They are divided into fluent and stable:

• Runaways. The upper part of the ground cover, undergrowth and young growth are burned. Such a fire has a high rate of spread, but at the same time bypasses places with high humidity. Random fires are typical in mid-spring, when only the top layer of combustible materials dries out.

• Sustainable. They move slowly, but do not leave the entire burning area with burnt-out dead and living ground cover. In this case, the underbrush and young growth completely burn out, and the bark and roots of the trees are also severely burned. Typically, such fires occur in mid-summer.

Horse

Covers branches, needles, leaves and the entire crown of the tree. A crown fire in a forest is characterized by the appearance huge amount sparks flying from pine needles and burning branches. They are picked up by the wind and spread to nearby areas (tens of meters), creating many ground fires. In strong winds they can spread hundreds of meters from the main source.

3. Steppe

Currently, these types of fires cause a lot of problems for people. And all because very little attention is paid to the development of measures to prevent and combat them. The policy of development of fallow and virgin lands, practiced in the second half of the 20th century, ruined the natural steppe vegetation. This consumer attitude towards steppe phytocenoses has survived to this day.

Now the plowed area of ​​the steppes in a particular region is 60-75%. In the recent past, when the emphasis was on increasing the “acreage under cultivation”, this figure reached 80-90%. That is, increasing productivity is achieved not through highly scientific agricultural technology, but by increasing land area. Periodically, natural fires occur in the steppes, which are exogenous factor environment. However, human activity leads to a manifold increase in their frequency.

4. Underground

Occurs during a forest fire or due to spontaneous combustion. There may also be a human factor in the swamp with the presence of a drained peat layer. Such fires are typical for taiga, forest-tundra and tundra, where there is a high content of peat deposits. The depth of fire penetration is 3 meters or more. The spread of such fires can reach several hundred meters per day.

Peat fires in artificially drained bogs have one peculiarity: they occur due to strong heating of the surface. In addition, the duration of combustion can reach several months and even years. Natural precipitation affects the dynamics of a fire only in its initial stages or in the case of low peat thickness. If a fire appears inside a peat horizon, its spread depends on the moisture content of the upper and lower layers of organic matter.

These types of fires do not have such a vast geography as the previous ones (forest and steppe). However, given the large volume of carbon emissions, they pose no less danger. Since peat has good water-holding capacity, it is very difficult to moisten a burning fire from the outside. Therefore, to extinguish such a fire you need a lot of water. That is, this is associated with significant economic losses, as well as a risk to people’s lives. For example, in 1972, while extinguishing underground fires in the Moscow region, several vehicles fell under burning peat. This led to death large quantity Human.

5. Technogenic

This includes fires at nuclear power plants, as well as oil, gas and oil-gas fires. During the operation of a well, fountains (pressure jets) may burst onto the earth's surface and catch fire. Conventionally, they are divided into oil (gas content is less than 50%, and more oil), gas (gas content is 95-100%), and gas-oil (oil is less than 50%, and more gas).

Oil combustion can occur in production equipment, tanks, and when it is spilled in open areas. If petroleum products ignite in tanks, an explosion is quite likely. Oil boils and blowouts are especially dangerous due to the presence of water in them. When boiling, the flame height and temperature increase very quickly (up to 1500°C). In this case, the foamed mass of the substance has a very violent combustion process. Putting out a fire in this case can take quite a while. long time. Let's move on.

Prevention and rules of conduct in case of fire

To prevent fire, every citizen must comply with a number of conditions for its prevention at enterprises, including residential buildings, in the forest, in the field, on peat bogs and in other places.

If we consider national economic facilities, then a fire safety regime is installed there and appropriate instructions are written. Moreover, this is done both for the facility as a whole and for individual sections, workshops and teams. The instructions indicate specially designated smoking areas, provide standards for storing various types of materials, and prescribe rules of conduct in case of fire.

A fire extinguisher is considered one of the most effective means of extinguishing fires. It must be borne in mind that it is not always permissible to extinguish a fire with water. For example, a water jet should not be directed at a burning electrical wire, as a person may receive an electric shock. After all, water is an excellent conductor. So before you put out a fire, turn off the power to the line. If this is not possible, use powder and carbon dioxide extinguishers. Incendiary substances and flammable mixtures are extinguished with sand, air-mechanical or chemical foam, as well as powder mixtures.

It is better to enter a smoky room together and move around, holding onto the walls so as not to lose your bearings. Before entering, be sure to put on a filtered or insulated gas mask with a hopcalite cartridge. Doors in burning rooms should be opened very carefully and used as cover. If there are people in a smoky and flaming room, they must be taken out immediately, after throwing a wet cloth or clothes over their heads. In cases where the exit is cut off by fire, evacuation is carried out through balconies and windows using manual, mechanical, stationary ladders and various lifts. Rescue ropes are also used.

Field, forest and peat fires occur due to careless handling of fire near populated areas, as well as due to unextinguished fires and sparks from the exhaust pipes of tractors and cars. Ripe grains, coniferous forests and dry grass ignite most easily. Therefore, it is forbidden to light a fire near forests, peat bogs, crops and reed thickets. It is also prohibited to smoke near forests (allowed only in specially equipped areas), stacks of mown bread and when working in cars, pickers, tractors and combines. Every car should have a spark arrestor.

Fire hazards

1. Effect of toxic combustion products

In the construction of modern buildings, synthetic and polymer materials are actively used. If a fire occurs, a person will certainly experience the effects of toxic products released when they ignite. Combustion products can contain up to 100 types of chemical compounds with harmful effects, but most often the cause of death is carbon monoxide. It reacts with hemoglobin 200 times more actively than oxygen. Because of this, red blood cells cannot supply the body with oxygen. According to statistics, 50-80% of people die in fires for this reason.

2. Reduced oxygen concentration in the fire zone

During a fire, the oxygen concentration in the surrounding air is greatly reduced. A decrease in oxygen levels by 3% will cause disruption of the body's motor functions.

3. Increased ambient temperature

If during a fire the ambient temperature is +70°C, then staying in this area for half an hour can lead to burns respiratory tract. When the oxygen content in the air is 6% and the temperature is 140°C, death occurs within a few minutes. In addition to causing burns, hot smoke greatly impedes visibility, and a person is poorly oriented in space.

4. Destruction of buildings

Some types of fires destroy even those buildings that do not burn in the fire. If you heat steel structures to 500-550°C, and concrete structures to 700-750°C, they will lose about 50% of their own strength. Therefore, to protect metal beams in high-rise buildings (10 and above), builders use wet plaster over a mesh. Metal structures are also protected with fire-retardant intumescent paints, which increase the fire resistance limit to approximately 40-45 minutes.

5. Open fire

And closing the list of “fire hazards” is fire. He is the most dangerous. First, fire burns all property; secondly, it completely or partially destroys residential buildings; thirdly, it causes burns. Modern medicine has achieved great success in the treatment of burns. But despite this, a person with a 2nd degree burn (30% of the body) has very little chance of survival.

Start of combustion under the influence of an ignition source Source: GOST 28157 89: Plastics. Methods for determining combustion resistance original document 1.17. Fire Starts... Dictionary-reference book of terms of normative and technical documentation

Flash; flaring up, burning. Ant. extinction, attenuation Dictionary of Russian synonyms. fire noun, number of synonyms: 5 fire (3) ... Dictionary of synonyms

BURN, I rush, I rush; owls Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary

Combustion begins under the influence of an ignition source. Source: ST SEV 383 87 EdwART. Dictionary of terms and definitions for security and fire protection equipment, 2010 ... Dictionary of emergency situations

Fire- the process of combustion initiation under the influence of an ignition source... Russian Encyclopedia of Occupational Safety and Health

fire- Combustion begins under the influence of an ignition source. [ST SEV 383 87] Topics fire safety … Technical Translator's Guide

fire- rus ignition (s), ignition (s) eng inflammation fra inflammation (f) deu Entzündung (f), Zündung (f) spa inflamación (f) rus ignition (s), ignition (s); fire (с) eng ignition fra allumage (m) deu Zündung (f) spa ignición (f) … Occupational safety and health. Translation into English, French, German, Spanish

fire- užsidegimas statusas T sritis chemija apibrėžtis Uždegamos medžiagos degimo pradžia. atitikmenys: engl. ignition rus. fire... Chemijos terminų aiškinamasis žodynas

Wed. 1. process of action according to Ch. ignite 2. The result of such an action. Ephraim's explanatory dictionary. T. F. Efremova. 2000... Modern explanatory dictionary Russian language Efremova

Fire, fire, fire, fire, fire, fire, fire, fire, fire, fire, fire, fire (Source: “Full accentuated paradigm according to A. A. Zaliznyak”) ... Forms of words

Books

• Field of omniscience, E. A. Kolkotin. In this book, the author makes an attempt to create a global cosmic worldview, in fact, a unified world socio-religious system. In the general concept, a large role in the book is given to...
• The third move, Emelyan Markov. The title of the novel "The Third Turn" is associated with fire terminology. Firefighters leave in one, two, three moves. The third move is sent when a fire occurs in the upper floors and you need to climb out the window.…

The concept of “fire” and “fire safety”.

A fire is a combustion outside a special source that is not controlled and can lead to mass casualties and deaths, as well as environmental, material and other damage.

Fire safety is a condition of an object in which the possibility of a fire is excluded, and if it occurs, the necessary measures are taken to eliminate the negative impact hazardous factors fire on people, structures and material assets

Fire safety can be ensured by fire prevention measures and active fire protection. Fire prevention includes a set of measures aimed at preventing a fire or reducing its consequences. Active fire protection (measures that ensure the successful fight against fires or explosive situations.

Fire protection has as its goal finding the most effective, economically feasible and technically sound methods and means of preventing fires and extinguishing them with minimal damage with the most rational use of forces and technical means of extinguishing.

Causes of fires.

The causes of fires are careless handling of fire, violation of fire safety rules, natural phenomena such as lightning, spontaneous combustion of dry vegetation and peat.

It is known that 90% of fires occur due to human fault and only 7-8% from lightning.

Naturally, in most specific cases it is impossible to accurately determine the source of the fire, much less find the culprits.

However, the fairly clear confinement of fire sources to places of anthropogenic activity, as well as the extreme uneven distribution of fire sources, cannot be explained by natural causes.

Even those few fires that, at first glance, are difficult to associate with human activity, upon closer examination often also turn out to be anthropogenic. For example, in 1998, in a hard-to-reach area of ​​the Nabilsky ridge (near the town of Lopatin), one of the fires, far from roads and populated areas, broke out immediately after a tourist group passed there.

It is important to note that significant areas of clearings and burnt areas burn quite regularly. Apparently, good combustible materials include logging residues, wood that has not been removed, charred trunks and woody debris, trees that have shrunk after previous fires, and dry grass. As a result, large areas are formed in which the forest practically does not renew.

Accidents at air defense facilities associated with strong explosions and fires can lead to severe social and economic consequences.

Fires are caused mainly by explosions of containers with explosive liquids and gases, short circuits in electrical wiring, explosions and fires of certain substances and materials.

Fires from the ignition of fuel and explosives during transportation are not uncommon (sparking of brake pads, ignition of axle boxes, detonation during sudden impacts).

In addition, in conditions of cramped production, substances considered non-flammable become dangerous. Thus, wood, coal, peat, aluminum, flour, grain and sugar dust, as well as dust from cotton, flax, hemp, and jute, explode and burn. Common chemicals such as turpentine, camphor, barium, pyramidon and others spontaneously ignite.

Characteristics of fires.

As I noted earlier, a fire is a spontaneously developing combustion that was not foreseen technological processes causing material damage, harm to the life and health of citizens, the interests of society and the state.

From the point of view of work related to extinguishing fires, rescuing people and material assets, fires are classified into three zones:

individual fires;

massive and continuous fires;

dying fires and smoldering in the rubble.

Fires are also divided into forest, peat, steppe, fires in populated areas, gas, gas-oil and petroleum products.

The zone of individual fires represents areas in the territories of which fires occur in individual areas, in individual zones and production facilities. Such fires are dispersed throughout the region, which makes it possible to quickly organize their mass extinguishing with the involvement of all available forces and means.

A zone of massive and continuous fires is an area where there are so many fires and fires that the passage and presence of the relevant units in it without localization or extinguishing measures is impossible, and rescue operations are difficult. Such zones arise in conditions of continuous development, compact forests, and the accumulation of large amounts of flammable materials.

A type of continuous fire is a firestorm. It is characterized by the presence of air convergence resulting from the combustion of a large amount of materials, which causes the formation of a convection flow, to which, in turn, air masses rush at a speed of 15 m/s. The conditions for the occurrence of a fire storm are: the presence of buildings or the spread of flammable material over an area of ​​up to 1000 hectares, reduced relative humidity(less than 30%), the presence of a certain amount of flammable materials in the corresponding area. In terms of wood - about 200 kg/m2 over an area of ​​1 km2.

The zone of dying fires and smoldering in the rubble is characterized by heavy smoke and prolonged (over two days) burning in the rubble. The actions of the relevant units are limited to the danger to human life due to thermal radiation and the release of toxic combustion products.

Dangerous smoke is considered to be one in which visibility does not exceed 10 m. The concentration of carbon monoxide in the air up to 0.2% soars, fatal poisoning of people when they stay in the area for 30-60 minutes, and at a concentration of 0.5-0.7 % - within a few minutes.

The cause of death may be the high temperature of a smoky environment. Inhalation of combustion products heated to 60°C, even with 0.1% carbon monoxide content, is fatal.

Forest fires are uncontrolled burning of vegetation that spreads throughout the forest. Depending on the heights at which the fire spreads, forest fires are divided into ground fires, underground fires and crown fires.

Ground forest fires develop as a result of the combustion of coniferous undergrowth, the above-ground layer of litter (fallen needles, leaves, bark, dead wood, stumps) and living vegetation (moss, lichens, grasses, shrubs). The front of a surface fire in strong winds moves at a speed of up to 1 km/h, at a height of 1.5-2 m.

Ground fires can be fleeting and common. Flash fires are characterized by rapidly moving flames and light gray smoke. Conventional ground fires spread relatively slowly. They are distinguished by the complete combustion of living and dead ground cover.

Crown forest fires are the combustion of the ground cover and biomass of the forest stand. Their speed of propagation is 25 km/hour.

They develop from ground fires when drought is combined with windy weather. Crown fires can be short-lived or common.

Underground (soil) forest fires are stages of development of ground fires. They occur in areas with peat soils. Fire penetrates underground through cracks in tree trunks. Combustion occurs slowly and flamelessly. After the roots burn, the trees fall, forming rubble.

Peat fires are the result of ignition of layers of peat at different depths. They cover large areas. Peat burns slowly, to the depth of its occurrence. Burnt-out areas are dangerous because sections of roads, equipment, people, and houses fall into them.

Steppe fires occur in open areas with dry vegetation. In strong winds, the speed of fire spread is 25 km/h. In cities and towns, individual (if a house or group of buildings catches fire), massive (if 25% of buildings catch fire) and continuous (when 90% of structures catch fire) fires are possible. The spread of fires in cities and towns depends on the fire resistance of buildings, building density, the nature of the terrain and weather conditions.

Fires involving gas, oil, gas, oil and petroleum products. During operation, pressure jets (fountains) can burst onto the surface of the earth, which often become fires. Conventionally, fountains are divided into gas (containing gas 95-100%), oil (containing oil more than 50%, and gas less than 50%), gas-oil (containing gas more than 50%, oil less than 50%).

The combustion of oil and petroleum products can occur in tanks, production equipment and when they are spilled in open areas. When petroleum products fire in tanks, explosions, boiling of flammable substances and their release can occur.

The phenomena of emissions and boiling of petroleum products, which is due to the presence of water in them, pose a great danger. During boiling, the temperature (up to 1500°C) and the height of the flame quickly increase. Such fires are characterized by violent combustion of a foamed mass of flammable substance.

Experience confirms the possibility of such phenomena as releases of petroleum products from reservoirs. Tons of the substance can be thrown over a distance of more than eight container diameters. In this case, the combustion area can reach several thousand square meters.

Fire of flammable materials such as roofing felt, bitumen, various cable products, foam rubber, leads to the release of toxic products of destruction (destruction) of burnt polymer materials into the air with the release of phosgene, hydrogen chloride and cyanide, chlorinated and aromatic carbons, which are substances with predominantly asphyxiating, generally toxic and neurotropic effects. Concentrations of these substances can reach life-threatening levels. The combustion of just 1 g of various polymer materials leads to the release of up to 144 mg of hydrogen chloride oxide, up to 167 mg of carbon monoxide, which far exceeds the damaging and lethal concentrations of these substances.

Fire in the house. One of the main reasons for its occurrence is human carelessness: irons or other household electrical appliances left energized, abandoned cigarette butts, violation of fire safety regulations, the use of any type of fire (candles, torches), cleaning household items with explosive substances in poorly ventilated areas near the fire, and also transfusion of flammable liquids in the vicinity of a fire source.

Defects in electrical installations can lead to a fire; careless and inept use of electrical appliances; the use of homemade electric heaters, spontaneous combustion of the TV, the inclusion of many devices in one outlet, ineptly (incorrectly) electrical wiring (network overload), the use of homemade fuses (“bugs”).

It is necessary to follow the rules for operating a gas stove. In the event of a gas leak, the room must be ventilated immediately. In this case, you must not smoke, light matches, or use the switch for electrical appliances.

If fires do occur, fire extinguishing agents are used to extinguish them.

Sources of forest fires. Fires in the Russian Federation.

The main sources (places of occurrence) of anthropogenic fires are:

places of traditional recreation of the population and the surrounding areas of villages. In these places, fires usually occur on weekends;

verges of public roads, including railways. According to ground surveys, in the northern part of the island, sparks from all-terrain vehicle mufflers are often the source of fires;

logging sites, including roads along which timber is removed or workers are transported on rotation.

Naturally, in most specific cases it is impossible to accurately determine the source of the fire, much less find the culprits. However, the fairly clear confinement of fire sources to places of anthropogenic activity, as well as the extreme uneven distribution of fire sources, cannot be explained by natural causes.

Fires pose a great danger to the life, health and property of people. Fires in nature usually occur under conditions of prolonged and severe drought and windy weather. A fire raging in a forest is a terrible enemy of the environment. After all, it brings enormous losses and sometimes leads to human casualties. Peat fires cause irreparable damage to nature, the consequences of which will take decades to eliminate. The article will define the term “fire” and reveal the concept of this phenomenon in nature, in particular in the forest.

Definition of fires

A fire is a combustion process that is uncontrollable, occurs outside a special source, causes material damage and poses a danger to human life and health. This is not necessarily an open flame; sometimes only incandescence and smoldering occurs. The definition of the concept of “fire” assumes that such a combustion process is capable of independently spreading beyond the boundaries of the places that are intended for starting and maintaining a fire.

The characteristics that necessarily accompany this phenomenon are the following:

• combustion;
• gas exchange;
• heat exchange.

Depending on the location of the fire, the classification of fires assumes the following types:

• industrial;
• household;
• natural.

A prerequisite for a fire to occur is the presence of the following components:

• ignition source;
• oxidant;
• flammable materials or substances.

Fire zones

The definition of fire assumes that such a phenomenon, regardless of its type, occurs in a certain space. This area can be divided into three zones:

• active combustion zone;
• heat affected zone;
• smoke zone.

The active combustion zone is the part of the space in which flame, smoldering or hot materials are directly present. In a flaming (homogeneous) fire, the boundary of this area is usually considered to be the surface of the flaming material and a thin layer of fire that glows. If the combustion is flameless (heterogeneous), then this zone is defined by the hot surface of the smoldering substance.

The heat impact zone refers to the space around the active combustion area, where heat exchange occurs between the surface of the fire and nearby materials and structures. The temperature here reaches values ​​that are dangerous for people and surrounding objects. A person cannot be in this area without special thermal protection.

Smoke zone is a space that is adjacent to the area affected by heat, and where people cannot be without special protection organs of vision and breathing. In such an area, firefighters' actions are difficult due to lack of visibility.

Below we will give a definition of a fire that occurs in the natural environment.

Definition of wildfires

A natural (landscape) fire is a combustion process that is uncontrollable, occurs spontaneously and spreads in environment. Occasionally, such a phenomenon occurs as a result of a lightning strike, a meteorite fall, or a volcanic eruption, but the main reason is human actions. Due to deliberate arson or natural fires occur. The definition of this phenomenon distinguishes between the following types of fires:

• forest fires;
• arrays;
• peat fires and organic fossil fires.

Among the listed types, there is one that is the most common and brings huge losses. These are forest fires.

Definition of forest fires

Forest fires are the burning of vegetation, which is uncontrollable and spontaneously spreads across the territory of the massif.

There are two main reasons for this phenomenon:

• Natural factors. This could be a lightning strike or spontaneous combustion of dry vegetation or peat.
• These include planned cleanup fires, deliberate or accidental fires, or simple failure to follow fire safety rules.

On at the moment the probability that such a forest fire will occur due to any natural factors is approximately 20%. The main cause of forest fires is still human activity.

The definition of a fire that develops in a forest area involves classification depending on the speed of spread and the nature of the fire.

Classification by speed of propagation

An important characteristic of forest fires is the speed of their spread. According to this indicator, such fires are classified as follows:

• weak;
• average;
• strong.

A weak forest fire is characterized by a spread speed that does not exceed 3 meters per minute. For an average fire, the value of this indicator varies from 3 to 100 meters per minute. And strong forest fires are characterized by a spread speed above 100 meters per minute.

Classification by nature of fire

Forest fires, depending on the nature of the fire, are classified as follows:

• grassroots;
• riding;
• underground (peat).

A ground fire is a fire that spreads through the lower tiers of trees and shrubs, litter, leaves and branches that have fallen. The majority of fires begin with this type. Further, when certain conditions are created, a forest fire transforms from a ground fire into a surface or underground one.

A crown fire is a fire that engulfs the forest canopy. In this case, the fire spreads through the treetops. This type of fire is typical of mountain forests. Strong winds contribute to the occurrence of crown fires.

The exact definition of a fire that occurs in the soil under forested areas will be given in the article below.

Peat fires: definition

A peat fire is a fire that occurs naturally or drained due to overheating of its surface by the sun's rays or due to careless handling of fire by a person.

Also, the causes of an underground fire can be a lightning strike or overhead and ground fires. Their flame penetrates deep into the peat layer near the roots of trees and bushes.

A peat fire can occur in the form of simple smoldering, when there is no ignition, or in the form of incoming masses of carbon dioxide. Such phenomena are difficult to detect. Often, smoldering peat reveals itself only by a slight emission of smoke from the soil. A long process of underground fire can cause repeated occurrence of ground fires.

Peat fires are classified depending on the number of fires and the depth of burning.

Classification of peat fires

Depending on the number of lesions they are divided into the following types:

• unifocal;
• multifocal.

Single-source underground fires occur in the event of a lightning strike or careless handling of fire by a person in a specific place. Multifocal are formed from several points of combustion of underground organic substances.

The classification of peat fires according to the depth of burning is as follows:

• weak;
• average;
• strong.

A weak peat fire is characterized by a burning depth of no more than 25 centimeters. The average underground fire has a size of this indicator from 25 to 50 centimeters. A strong peat fire is characterized by a burn depth of more than 50 centimeters.

Conclusion

Fires, depending on the place of origin, are divided into industrial, domestic and natural. The space in which a fire occurs is divided into three zones: active combustion, thermal effects and smoke. In turn, they are further classified into forest and peat. The main reason for their occurrence is human activity. The definition of a fire that occurs in a forest area involves an additional classification based on the speed of spread. Depending on the nature of the fire, this phenomenon can be ground-level, overhead or underground. Peat fires are divided into types depending on the number of fires and the depth of burning.