Environmental Issues

Fire behavior results from interaction of fire with its environment and the interplay between different environmental components. At any moment of time, fire behavior can be deciphered from the state of individual components of the fire environment and their interactions. Fire environment connotes the conditions, influences and modifying forces that affect and control fire behavior.

The environment consists of three components, namely topography, fuel and air mass. Topography includes slope, aspect, configuration, and land elevation. Fuel serves as the source of thermal or heat energy and influences fire behavior. Air mass includes multifarious weather elements such as precipitation and humidity. These components vary over space and time. Topography and fuel characteristics, except moisture of dead fuel, change very slowly with time but air mass shows considerable variation. All three components can show significant spatial variation. Solar energy facilitates interaction between the three environmental components to the extent that changes in one component cause variations in the other two. Non-uniform or differential heating of the sun results in creation of micro and macro climatic patterns, which influence fire behavior. Like the sun, fire serves as a heat source in the environment.

However, its proximity causes extreme temperature variations between itself and the adjacent environment, resulting in adverse effects on the latter. Scale of environmental influence on fire behavior varies directly with fire intensity. More intense the fire, higher the horizontal and vertical extent of the concerned environment Fire behavior changes as it moves horizontally, across the terrain, and vertically. It also varies with time. Fire behavior is the culmination of principles from numerous fields including aerodynamics, chemistry, combustion physics and thermodynamics, making it difficult to foretell. However, even the most unusual fires observe compliance with physical laws and can be accurately predicted by firefighters with increase in experience.