Forest fires occur quite often. In order for a dry tree to light up, just one small spark or lightning strike is enough. Given that in most countries, weeds are set on fire in the fields, the number of fires increases several times.
The larger the country's territory, the more fires occur on it. And if persistent drought prevails, then trees and shrubs can ignite even for no apparent reason. There is a ground and top fire, there are also soil fires and a host of other types of fires. But first things first.
What is a forest fire
This term refers to uncontrolled fire, which spontaneously spreads through the forest. In the process of such a fire, partial or complete burning out of vegetation located above ground level, forest litter (fallen leaves, branches, etc.) and fertile soil layer occurs. As a result, nothing has been growing in the area affected by the fire for a long time. In addition, animals often die due to forest fires.
Natural disasters of this type are very dangerous, since fire spreads very quickly over vast areas. Most often, by the time a forest fire is detected, it covers large areas, which greatly complicates the process of extinguishing.
Causes of occurrence
Most often, fire comes from lightning, they account for more than 8% of fires. Moreover, it all depends on the terrain. In forests dominated by young trees, natural disasters are much less common.
Another cause of forest fires is people. In some situations, fire comes from deliberate action to destroy weeds. In addition, in the spring and summer, people go to barbecue or for mushrooms. In this case, one cigarette or firebrand in a fire is enough. As a result of such negligence, dry grass instantly ignites, and flames very quickly spread to dry wood.
Forest Disaster Classification
Based on the nature of the fire, soil, ground and top fires are distinguished. Further, natural disasters are classified by their spread rate. Based on this, the ground fire is divided into the following categories:
- Weak. A fire up to 0.5 m high covers 1 meter of the territory in just a minute.
- Medium (height up to 1.5 m). It spreads at a speed of up to 3 m / min.
- Strong (more than 1.5 m). Covers 3 meters in less than 3 minutes.
In turn, the speed of a riding fire is:
- Up to 3 m / min. This speed is considered weak.
- From 3 to 100 m / min. In this case, they speak of the average propagation speed.
- More than 100 m / min. - strong fire.
From this it can be seen that a steady riding fire spreads at a speed of more than 100 meters in one minute. Accordingly, its scale is simply impossible to imagine.
There is also a soil fire, which also spreads quite quickly. In this case, the burnup depth is taken into account:
- Less than 25 cm is a slight fire.
- From 25 to 50 cm - medium.
- More than 50 cm - belongs to the category of strong.
In addition, fire is classified according to the area of ignition:
- From 0.1 to 2 ha is typical for normal fires.
- Up to 20 ha indicates low fire.
- 20-200 ha is an average fire.
- Up to 2000 ha is characteristic of a major disaster.
- Over 2,000 ha is already a disaster.
If we talk about the duration of the disaster, then in case of horse fires, a territory of about 10-15 days burns (depending on the level of fire). During this time, more than 500 hectares can burn out. Let us consider in more detail each type of fire.
Horse forest fire
Each fire is extremely dangerous for wildlife, animals, birds and, of course, for humans. Very often, the flame comes to small graying, located near the forest. As a result, fire quickly engulfs homes. Therefore, if an unusual haze appeared in the sky, a burning smell is observed, then it is necessary to immediately contact the Ministry of Emergencies.
Horse fire affects the forest canopy. Most often, this type of fire is the result of the development of a low flame. Thus, we can say that the ground fire is a component of the horse.
The occurrence of fire, which is located above the surface of the soil, contribute to natural factors. For example, strong winds and steep slopes can cause a fast propagation of a riding fire. Most often, such fires occur in the summer, when arid and hot weather prevails.
In this type of fire, trees usually die completely. If we talk about the nature of burning, then emit a quick and steady riding fire. The latter type is characterized by the fact that the crown of the tree burns out gradually, as the grassroots develops. In this case, the flame does not move along the canopy. Such fires are also often called general fires. If we talk about a runaway fire, then in this case, fire, on the contrary, spreads along the canopy and can even get ahead of the ground fire. Also, in this case, jumps in the flame are observed, at the moment of which the fire can hit areas with greater speed.
As mentioned earlier, horse and ground fires are practically one. Therefore, it is worth saying a few words about the second type.
Ignition in the lower tiers
In a ground fire, fire moves along the underlying layer. First of all, grass, undergrowth, as well as undergrowth, light up. Ground fire usually moves in a semicircle, forming the outline of the main flame on the ground. The result is an edge.
If we talk about the nature of fires, then the bottom burning can also be fluent or stable. In the first case, the edge of the fire moves very quickly at a speed of more than 0.5 m / min. As a result, only the soil cover burns out. If we are talking about stable ground fire, then in this case the speed of the circuit is much lower. Correspondingly, not only the underlying layer burns out, but also rotten stumps and deadwood. In this case, strong smoke formation is observed.
Soil ignition
Underground fires infect the root system of trees. They do not differ in a pronounced flame. Soil fire spreads deep into the earth and can move at speeds of up to 1 km per hour. Moreover, such fires are considered the most difficult, since they are very difficult to extinguish. Soil fire becomes the cause of the grassroots, which in turn provokes the appearance of a high flame.
Extinguishing measures
The most diverse equipment is used for fire fighting: helicopters and airplanes. Due to the discharge of liquid extinguishing compounds, the fire can be quickly localized. To determine the source of ignition, screening is carried out.
However, in some cases annealing (head fire) is formed. It burns fire extinguishing liquids before they even arrive. In this case, a shock wave is used. For this, an explosion is made in front of the fire front, which initiates the appearance of a reflective screen. Thanks to this, it is possible to stop the further spread of the flame and extinguish using standard methods.
Preventive measures
First of all, experts are trying to predict the occurrence of fire in a particular zone, based on weather conditions and data obtained from the terrain. In this case, the forest fire coefficient is calculated.
In order to reduce forest loss, a lot of organizational activities are carried out. First of all, fire and preventive maintenance is performed. Sanitary deforestation is also carried out. In this case, all old and dried trees are destroyed. Also, forest belts that are dangerously close to human settlements are cut down. Special trenches are laid along the forest line, which in case of fire will not allow the fire to go further.
In addition, forest fires are periodically monitored, special observation masts and towers are installed. Thanks to ground observation, it is very often possible to prevent the occurrence of natural tragedy.