This paper investigates the cause of ignition of wooden shields during surface fire fronts. For this purpose an experiment was conducted in which a zone 50m in length and 10m in width was chosen as the experimental site. Wooden shields (made of spruce boards) and samples of high-moor and valley peat were placed in this zone. In the experiment it was ascertained that to ensure safety during the surface fire in absence of firebrands and embers it was necessary to clear a perimeter around the zone not less than 5m in width, and remove cleared fuels. To reduce the risk of fence ignition, it was necessary to make the fences permeable. It was found that grass fires turn into peat fires if there is a conductor of combustion above the layer of peat.

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The results of seminatural experiments on the study of steppe and field wildfires characteristic of the steppe and forest-steppe zones of Western Siberia are presented. Using infrared (IR) thermography methods, the main thermal characteristics of the fire front are derived, the flame turbulence scale is estimated, and changes in the structure function of the air refractive index are analyzed in the vicinity of a fire. The effect of a model fire on the change of meteorological parameters (wind velocity components, relative air humidity, and temperature) is ascertained. Large-scale turbulence is observed in the front of a seminatural fire, which is absent in laboratory conditions. The predominance of large-scale turbulence in a flame results in turbulization of the atmosphere in the vicinity of a combustion center. Strong heat release in the combustion zone and flame turbulence increase the vertical component of the wind velocity and produce fluctuations in the air refractive index, which is an indicator of atmospheric turbulization. This creates prerequisites for the formation of a proper wind during large fires. Variations in the gas and aerosol compositions of the atmosphere are measured in the vicinity of the experimental site.

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