Fires pose a great danger to the life, health and property of people. Fire in nature usually occurs in conditions of prolonged and severe drought and windy weather. Flames raging in the forest - 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 elimination of the consequences of which will take decades. The definition of the term “fire” will be given in the article, the concept of this phenomenon in nature, in particular in the forest, is disclosed.
Fire detection
Fire is a combustion process that cannot be controlled, occurs outside a special focus, causes material damage and poses a danger to human life and health. This is not necessarily an open flame, sometimes only incandescent and smoldering occurs. The definition of the concept of “fire” implies that such a combustion process is capable of self-propagation beyond the boundaries of places that are designed to breed and maintain fire.
The characteristics that necessarily accompany this phenomenon are as follows:
- combustion;
- gas exchange;
- heat exchange.
Depending on the place of burning, the classification of fires suggests the following types:
- industrial;
- household;
- natural.
A prerequisite for the occurrence of a fire is the presence of such components:
- ignition source;
- oxidizing agent;
- combustible materials or substances.
Fire zones
The definition of fire suggests that such a phenomenon, regardless of its type, occurs in a certain space. This area can be conditionally divided into three zones:
- zone of active combustion;
- heat exposure zone;
- smoke zone.
The active combustion zone is a part of the space in which the flame, smoldering or incandescent materials are directly present. In case of fiery (homogeneous) ignition, the boundary of this section is 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 determined by the red-hot surface of the smoldering substance.
The heat-affected zone refers to the space around the active combustion site, where heat is exchanged between the surface of the fire and the nearby materials and structures. The temperature here reaches values dangerous to people and surrounding objects. A person cannot be in this zone without special thermal protection.
A smoke zone is a space that adjoins a heat exposure area, and where people cannot be without special protection of the organs of vision and breathing. At such a site, firefighters are hindered by a lack of visibility.
Below we will give a definition of the fire that occurs in the natural environment.
Definition of natural fires
Natural (landscape) fire is a burning process that is not subject to control, arises spontaneously and spreads in the environment. Occasionally, this phenomenon occurs as a result of a lightning strike, a meteorite or a volcanic eruption, but the main reason is human actions. Due to deliberate arson or careless handling of fire , natural fires occur. The definition of this phenomenon distinguishes between these types of fires:
- Forest fires;
- fires of steppe massifs;
- peat fires and ignitions of organic minerals.
Among the listed species, there is one that is most common and causes huge losses. These are forest fires.
Definition of forest fires
Forest fires are a burning of vegetation that cannot be controlled and spontaneously spreads over the territory of the massif.
The main causes of this phenomenon are two:
- Natural factors. This can be a lightning strike or spontaneous combustion of dry vegetation or peat.
- Anthropogenic factors. These include planned cleansing arsons, deliberate or accidental fires, or trivial non-compliance with safety rules when handling fire.
At the moment, the likelihood 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 is unfolding in a forest involves a classification depending on the speed of propagation and on the nature of the fire.
Speed Classification
An important characteristic of forest fires is the speed of their spread. According to this indicator, such fires are classified as follows:
A low forest fire is characterized by a propagation 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 propagation speed above 100 meters per minute.
Fire classification
Forest fires are classified as follows according to the nature of the fire:
- grassroots;
- horse;
- underground (peat).
Ground fire is a fire spreading over the lower tiers of trees and shrubs, litter, leaves and branches that have fallen. The bulk of ignition begins with this type. Further, when certain conditions are created, a forest fire from the ground is transformed into a horse fire or an underground fire.
Horse fire is a fire that covers the canopy of the forest. In this case, the fire spreads over the crowns of the trees. This type of fire is typical of mountain forests. Rising fires are promoted by a strong wind.
An exact definition of the fire that occurs in the soil under the forests will be given in the article below.
Peat Fires: Definition
Peat fire is the ignition of a natural or drained peat bog due to overheating of its surface by the sun's rays or during a person's careless handling of fire.
Also, causes of underground fire can be a lightning strike or top and bottom fires. Their flame penetrates deep into the peat layer near the roots of trees and shrubs.
Peat fire can occur in the form of simple decay, when ignition is absent, or in the form of combustion with incoming masses of carbon dioxide. Such phenomena are difficult to detect. Often, smoldering peat gives itself away with only a small amount of smoke from the soil. The long process of underground fire can cause repeated occurrence of lower fires.
Peat fires are classified depending on the number of outbreaks and the depth of burnout.
Peat fire classification
Peat fires are divided into the following types depending on the number of outbreaks:
- single focal;
- multi-focal.
Single-source underground fires occur in the event of a lightning strike or careless handling of fire by a person in a particular place. Multifocal are formed from several combustion points of underground organic substances.
The classification of peat fires by the depth of burnout is as follows:
A weak peat fire is characterized by a burnout depth of not more than 25 centimeters. The average underground fire has a value of this indicator from 25 to 50 centimeters. A severe peat fire is characterized by a burnout depth of more than 50 centimeters.
Conclusion
Fires, depending on the place of occurrence, are divided into industrial, domestic and natural. The space on which the ignition occurs is divided into three zones: active combustion, heat exposure and smoke. In turn, natural fires are additionally classified as forest and peat. The main reason for their occurrence is human activity. The definition of a fire occurring in a forest area implies an additional classification according to the speed of propagation. Depending on the nature of the fire, such a phenomenon can be grassroots, high and underground. Peat fires are divided into types depending on the number of foci and the depth of burning.