The successful harnessing of fire for light, heat and cooking is one of the main things that separate humans from animals. For thousands of years this elemental force of nature has been regarded with fear, awe and appreciation and still drives our civilization today.
Fire is a rare example of chemistry in action, a visible and obvious transition of matter from one state to another. In order for a fire to start, it needs fuel, heat and oxygen. The fuel can be wood, paper, gasoline or nearly anything else flammable. The heat source is provided by natural or artificial means, such as a lightning strike or a match. The heat source raises the fuel to its ignition temperature and kindles the blaze. The fire will continue to burn until all the fuel is used up, or if it is deprived of oxygen. Dousing a fire by pouring water on it actually works by first removing the oxygen from the immediate area around the fire, and secondly by cooling the fuel below the ignition point.
Gravity is an under appreciated participant in the entire process of fire. Gravity determines how the fire burns. Since the heat and gases emitted by a fire are lighter than air, they rise, creating the characteristic pointed shape of a flame. This chimney effect also helps keep the fire burning, with colder fresh air getting pulled in from the bottom and depleted air rising and moving away from the flame.
There are many factors that affect the ignition, size and spread of a fire. The size of the fuel determines how quickly it ignites and burns. Larger pieces of fuel take more time to heat to ignition temperature, but keep burning longer. This is why small pieces of kindling are used to start a campfire, with larger pieces added later in order to keep it burning.
It has been said that fire is a fine servant, but a terrible master. Simple steps toward fire prevention and knowledge of how the process works arm everyone against fire dangers.