Flames

A flame is the visible, gaseous part of a fire produced by the rapid oxidation of a fuel in the presence of an oxidizer, typically the oxygen in air. The flame emits light and heat as chemical energy is released and excited molecules and particles radiate photons. The appearance and temperature of a flame depend on the fuel, the amount of oxygen, pressure, and how completely the fuel burns.

Flames vary in color and temperature. Blue flames usually indicate efficient combustion at higher temperatures, often seen in well-oxygenated hydrocarbon flames. Yellow or orange flames are common in less complete combustion, where soot particles glow and heat the surrounding gas. The flame structure generally includes zones of preheating, reaction, and post-combustion, and it may be premixed (fuel and oxidizer mixed before ignition) or diffusion (fuel and oxidizer meet in the flame).

In practical terms, flames are stabilized by heat transfer, fuel supply, and mixing with air. Small, well-ventilated flames, such as those in a gas stove or Bunsen burner, are designed to produce predictable, controllable flames. Diffusion flames, such as those from a candle or a oil lamp, can exhibit a bright yellow region due to soot. Flames can be extinguished by removing any of the three elements of the fire triangle: heat, fuel, or oxidizer.

Safety and environmental considerations accompany flame use. Flames pose burn hazards and can emit toxic gases like carbon monoxide if combustion is incomplete. In many contexts, flames enable heating, cooking, and various industrial processes, while requiring precautions to prevent uncontrolled fires.