The Basic Facts About Fire

Fire has fascinated humans since prehistory, and the use of it for cooking, warmth, and other purposes is widespread around the world. It is important to know some basic facts about fire in order to safely and effectively manage it.

Fire is the visible effect of a chemical reaction called combustion. The chemical reaction takes place between oxygen in the air and some kind of fuel, such as wood or gasoline. The fuel must be heated to a high temperature for the reaction to begin; this heat is produced by friction, lightning, a match, or something else that causes the surface of the fuel to get hot. Once the fuel reaches its ignition temperature, it will keep burning as long as there is sufficient heat, fuel, and oxygen present. The heat energy produced by the burning fuel is converted to light and thermal energy by the atoms of the burning material.

The light emitted by the burning fuel and gas molecules of the flame is a result of a physical phenomenon called incandescence. When the atoms of the fuel and oxidizer are heated, they move at faster rates as they jiggle and vibrate. This vibration gives the emitted light its color and brightness. The particles of the fuel and oxidizer can also break apart and rejoin with other gas molecules in the air to form new products, such as water and carbon dioxide if the chemical reaction is complete, or soot if it is not.

A fire spreads from a source to other nearby combustible materials by radiation and contact with other fuel. It can also spread from plant to plant or tree to tree by a process called slash-and-burn cultivation, which was an essential part of the Neolithic revolution in agriculture that began in 7000 bce. This process burned brush and trees to clear fields for cultivation, but also created ash that provided valuable nutrients for crops.

In some places, such as the deserts of North Africa and the tropics of South America, the presence of fire in the natural environment is very important to human survival. In the absence of fire, some plants will not grow, and others may not produce seeds. Many pine trees, for example, have their seeds enclosed in a hard shell of pitch, which must be melted by fire in order to release the seeds and allow germination.

The burning of fuels such as coal, oil, and natural gas produces heat energy that can be used to produce electricity in power stations. The steam generated by the heating of the fuels drives turbines that spin generators to produce electric current. The heat from the burning fuels can also be used to do mechanical work, such as turning a crank on an engine or driving a car. When a fire is not managed properly, it can devastate homes and businesses, damage forests and other habitats, destroy wildlife, and threaten human lives. Fire can be extinguished by cooling it to below its ignition temperature, using water or other nonflammable liquids or solids.