A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, grass fire, hill fire, peat fire, vegetation fire, veldfire, and wildland fire may be used to describe the same phenomenon depending on the type of vegetation being burned.

Causes

The four major natural causes of wildfire ignitions are :

1. lightning

2.volcanic eruption

3. sparks from rockfalls

4.spontaneous combustion

*The most common cause of wildfires varies throughout the world.

1.       United States,

2.      Canada

3.      Northwest China

 

Fire type

• Ground fires are fed by subterranean roots, duff and other buried organic matter

• Crawling or surface fires are fueled by low-lying vegetation such as leaf and timber litter, debris, grass, and low-lying shrubbery.

• Crown, canopy, or aerial fires burn suspended material at the canopy level, such as tall trees, vines, and mosses.

Effect of weather

Heat waves, droughts, cyclical climate changes, and regional weather patterns such as high-pressure ridges can increase the risk and alter the behavior of wildfires dramatically. Since the mid 1980s, earlier snowmelt and associated warming has also been associated with an increase in length and severity of the wildfire season in the Western United States

Fire control consists of depriving a fire of fuel, oxygen or heat  to prevent it from spreading or to put it out entirely.

 

Class-A fires

The standard and most common way to control a class-A fire (the combustion of a flammable material with oxygen and heat) is to remove heat by spraying the burning solid fuels with water from a fire-hose connected to a pump.

Class-B fires

Class-B fires (hydrocarbons, petroleums, and fuels on fire) require much different handling than the standard water approach. Many fuels, such as gasoline or oil float on water, and water would actually end up spreading the fire further.

One way to control a class-B fire would be to dump chemical dust on it—this is also a method for handling class-A fires, and actually tends to be preferable because sprayed water tends to cause property damage.

Class-C fires

Class-C fires are electrical fires—fires that are caused by an electrical source and get their heat from electricity. These fires are dangerous because if water is used on them, electrical current will be passed through the stream and back into the firefighter.