Forest fires are wildfires which take place in a forest. They can be large because of the huge amount of fuel in a forest. Other types of wildfires are grass, brush and hill fires. Man causes much of the forest fires by not putting out campfires or leaving burning cigarettes. Fires can have natural causes, like lightning, volcanic eruptions and sparks from falling rocks. Humans can set a fire on purpose. This is called arson.
In the United States, about eighty percent of forest fires are caused by man. Each year between four and nine million acres of land are destroyed in the United States by forest fires. Billions of dollars must be spent to try to extinguish these fires. Lives are also lost. Although forest fires occur around the world, most occur in the western part of the United States.
Several factors cause a wildfire to spread. Weather plays a big part in determining how far and how fast a forest fire will spread. In periods of drought, more forest fires occur because the grass and plants are dry. The wind also can be a big factor in the spread of a forest fire. The outdoor temperature and amount of humidity in the air also play a part in controlling a forest fire.
Fuel, oxygen and a heat source must be present for a fire to burn. The amount of fuel determines how long and fast a forest fire can burn. Many large trees, bushes, pine needles and grass abound in a forest for fuel. Flash fires occur in dried grass, bushes and small branches. They can catch fire quickly and then ignite the much heavier fuels in large trees. Green vegetation is not usually considered flammable, but intense heat can dry these out quickly and provide fuel for the fire.
The topography, shape of the land, plays a role in the spread of a forest fire. A forest fire races faster uphill. The slopes and sides of a mountain will burn quickly. A crown fire is one which races across treetops. In California, winds called Santa Ana spread fires very quickly.
Forest fires are very difficult to control. They can quickly become huge and can move up to six miles per hour. They can jump over roads and rivers. They can change direction due to wind changes. Sometimes a tornado can be formed when winds around a forest fire begin a twirling motion.
Firefighters used two main plans to control a forest fire. The first is called a firebreak. This involves getting rid of any fuel that is in the path of a forest fire. The firefighters will clear trees, bushes, and other fuel in a path ahead of the fire so that it will have no more fuel and will stop. Controlled burning can help with a firebreak. Firefighters purposely set fires to clear out any underbrush which would feed the fire.
The second technique is called an airdrop. Firefighters can call upon airplanes and helicopters to bring in special chemicals or water to the area. These will drop thousands of gallons over areas of the land which may be hard for the firefighters to reach.
Campers should be very careful to put out any campfire they have used before leaving the area. They should also build the fire in a safe location and make a good campfire pit to keep the fire isolated.
Forest fires which occur naturally can benefit nature. The dead or decaying matter is burned, and nutrients are returned to the soil. The fires can remove diseased plants from an area. They can burn out some of the thick trees and allow sunlight to penetrate to the forest floor. This will allow new seedlings to grow.
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