The discovery of fire has perhaps been one of the greatest innovations of all time. Almost everyone basically knows what a fire looks and feels like. But there are actually four parts to a fire, all equally dangerous.

• fire gas: These are the gases created by the combustion process. They’re invisible to the naked eye, but they exist and include such poisonous substances as carbon monoxide.
• flame: This is the light given off by the burning gas. As long as the three essential ingredients, fuel, oxygen, and heat, are there, it can be seen.
• heat: This is the part of the fire that you feel as warmth. It can also burn your skin. A normal fire usually burns at around 1,100º. Most turkeys are cooked at 400º, so a normal fire is about three times as hot.
• smoke: Smoke is a harmful vapor cloud mixed with a fine power of solid particles. A large number of fire injuries are caused by smoke inhalation, which damages the lungs. This is why most firefighters were masks and air packs.

Fires don’t always burn just wood. High heat can make plastic and even some metal catch fire or help flames travel distances. Too much fuel and the fire can burn a large area. Too much oxygen in the form of winds can spread and consume large regions. As a fire is pushed further and further, it finds more fuel. Before long, the fire is out of control and spreading faster than it can be contained. The fire may even hit temperatures near 1,300º.

Fire can behave in many different ways. In building fires, the air in a room can become so hot that everything inside bursts into flame in one huge explosion. This is known as a flashover. The harder a fire burns, the more air its uses up. Inside buildings, when the oxygen in a room is almost used up, the fire begins to die down from lack of the substance. The flames lower and the room fills with smoke. But if you open the door to the room at that time, the fire sucks oxygen in so hard that fire gases explode. This is known as a backdraft, and its force can blow a person across a street.

Fires can also break out almost anywhere. There have been great blazes that consume entire buildings or cities. When a fire burns a large area, sometimes burning entire town, it is generally known as a conflagration. Huge fires caused by enormous numbers of separate fires all burning together, like those caused in several cities on which incendiary bombs were dropped in World War II, are known as firestorm conditions. Wildfires rage unchecked across grassland or forests. Forest fires are often devastating because they are so difficult to put out.

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Forces of Nature: ThinkQuest 2000 (Team #C003603)

http://library.thinkquest.org/C003603/english/forestfires/whatsafire.shtml