Fires

Fires are a rapid exothermic oxidation, releasing heat, light, and reaction products such as smoke and ash. Most fires rely on a self-sustaining flame that requires heat to reach the ignition temperature of a fuel, fuel to provide energy, and an oxidizer (usually atmospheric oxygen). This three-element set is known as the fire triangle; removing any element stops the fire.

In typical fires, heat causes fuels to release flammable gases that mix with air and ignite, producing flames. Heat transfer occurs mainly by convection, radiation, and to a lesser extent conduction. Flame temperature varies, often several hundred to over a thousand degrees Celsius.

Fires occur naturally (wildfires triggered by lightning or lava) and from human activities (accidental fires, arson, industrial accidents). They can occur in forests, grasslands, urban areas, and industrial facilities. Fire behavior depends on fuel type, moisture, wind, and topography. Containment is more difficult in windy, dry conditions or with abundant continuous fuels.

Suppression and safety: firefighters aim to remove heat, starve fuel, or limit oxygen. Methods include applying water to cool, removing or isolating fuel sources, and sealing air flow; chemical suppressants may be used in some situations. Early detection, alarms, proper storage of flammable materials, and building codes with fire-resistant materials reduce risk. Fire management for ecosystems may include controlled or prescribed burns to reduce fuel loads and promote renewal.

Ecological and societal impact: fires influence landscapes, species composition, soil properties, and air quality. Some ecosystems depend on periodic fires for regeneration. Fires can cause property damage, injuries, and economic costs, while climate factors can influence fire frequency and intensity.