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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. A wildfire differs from other fires by its extensive size, the speed at which it can spread out from its original source, its potential to change direction unexpectedly, and its ability to jump gaps such as roads, rivers and fire breaks. Wildfires are characterized in terms of the cause of ignition, their physical properties such as speed of propagation, the combustible material present, and the effect of weather on the fire. Some plant species depend on the effects of fire for growth and reproduction, although large wildfires may also have negative ecological effects. One of the more controversial techniques is controlled burning: permitting or even igniting smaller fires to minimize the amount of flammable material available for a potential wildfire. Wildfires differ from other fires in that they take place outdoors in areas of grassland, woodlands, bushland, scrubland, peatland, and other wooded areas that act as a source of fuel, or combustible material. While the causes of wildfires vary and the outcomes are always unique, all wildfires can be characterized in terms of their physical properties, their fuel type, and the effect that weather has on the fire. This can be problematic because public fire policies, which relate to fires of all sizes, are influenced more by the way the media portrays catastrophic wildfires than by small fires. The thousands of coal seam fires that are burning around the world, such as those in Centralia, Burning Mountain, and several coal-sustained fires in China, can also flare up and ignite nearby flammable material. Forested areas cleared by logging encourage the dominance of flammable grasses, and abandoned logging roads overgrown by vegetation may act as fire corridors. Annual grassland fires in Southern Vietnam can be attributed in part to the destruction of forested areas by herbicides, explosives, and mechanical land clearing and burning operations during the Vietnam War. For example, fuels uphill from a fire are more readily dried and warmed by the fire than those downhill, yet burning logs can roll downhill from the fire to ignite other fuels. Overall, fire types can be generally characterized by their fuels as follows:
Wildfires occur when all of the necessary elements of a fire triangle come together in a wooded area: an ignition source is brought into contact with a combustible material such as vegetation, that is subjected to sufficient heat and has an adequate supply of oxygen from the ambient air. A high moisture content usually prevents ignition and slows propagation, because higher temperatures are required to evaporate any water within the material and heat the material to its fire point. As the front approaches, the fire heats both the surrounding air and woody material through convection and thermal radiation. Even before the flames of a wildfire arrive at a particular location, heat transfer from the wildfire front warms the air to 800C (1,470F), which pre-heats and dries flammable materials, causing materials to ignite faster and allowing the fire to spread faster. Torching and fires in tree canopies encourage spotting, and dry ground fuels that surround a wildfire are especially vulnerable to ignition from firebrands. Spotting can create spot fires as hot embers and firebrands ignite fuels downwind from the fire. In Australian bushfires, spot fires are known to occur as far as 10kilometers (6mi) from the fire front. Years of precipitation followed by warm periods can encourage more widespread fires and longer fire seasons. Fires in Europe occur frequently during the hours of 12:00 p.m. and 2:00 p.m. Wildfire suppression operations in the United States revolve around a 24-hour fire day that begins at 10:00 a.m. due to the predictable increase in intensity resulting from the daytime warmth. Although some ecosystems rely on naturally occurring fires to regulate growth, many ecosystems suffer from too much fire, such as the chaparral in southern California and lower elevation deserts in the American Southwest. The increased fire frequency in these ordinarily fire-dependent areas has upset natural cycles, destroyed native plant communities, and encouraged the growth of fire-intolerant vegetation and non-native weeds. Because they are highly flammable, they can increase the future risk of fire, creating a positive feedback loop that increases fire frequency and further destroys native growth. Also, fires in the rainforest, along with drought and human involvement, could damage or destroy more than half of the Amazon rainforest by the year 2030. Such adaptations include physical protection against heat, increased growth after a fire event, and flammable materials that encourage fire and may eliminate competition. For example, plants of the genus Eucalyptus contain flammable oils that encourage fire and hard sclerophyll leaves to resist heat and drought, ensuring their dominance over less fire-tolerant species. Grasslands in Western Sabah, Malaysian pine forests, and Indonesian Casuarina forests are believed to have resulted from previous periods of fire. Too frequent fires favor herbaceous plants, and infrequent fires favor species typical of Bahamian dry forests. Increased fire byproducts in the stratosphere can increase ozone concentration beyond safe levels. Forest fires in Indonesia in 1997 were estimated to have released between 0.81 and 2.57 gigatonnes (0.89 and 2.83 billion short tons) of CO2 into the atmosphere, which is between 13%40% of the annual carbon dioxide emissions from burning fossil fuels. Smoldering surface fires started to occur sometime before the Early Devonian period 405 million years ago. Wildfires during the Paleozoic and Mesozoic periods followed patterns similar to fires that occur in modern times. Surface fires driven by dry seasons are evident in Devonian and Carboniferous progymnosperm forests. Lepidodendron forests dating to the Carboniferous period have charred peaks, evidence of crown fires. In Jurassic gymnosperm forests, there is evidence of high frequency, light surface fires. The increase of fire activity in the late Tertiary is possibly due to the increase of C4-type grasses. As these grasses shifted to more mesic habitats, their high flammability increased fire frequency, promoting grasslands over woodlands. Human involvement
The human use of fire for agricultural and hunting purposes during the Paleolithic and Mesolithic ages altered the preexisting landscapes and fire regimes. However, while ancient Hebrew, Greek, and Roman writers were aware of fires, they were not very interested in the uncultivated lands where wildfires occurred. From the Middle ages, accounts were written of occupational burning as well as customs and laws that governed the use of fire. Scottish botanist David Douglas noted the native use of fire for tobacco cultivation, to encourage deer into smaller areas for hunting purposes, and to improve foraging for honey and grasshoppers. In the post-World War II Baltic region, socio-economic changes led more stringent air quality standards and bans on fires that eliminated traditional burning practices. However, human influence caused an increase in fire frequency. Dendrochronological fire scar data and charcoal layer data in Finland suggests that, while many fires occurred during severe drought conditions, an increase in the number of fires during 850 BC and 1660 AD can be attributed to human influence. However, a period of increased fire frequency between 1750 and 1870 was suggested by charcoal data from North America and Asia, attributed to human population growth and influences such as land clearing practices. This period was followed by an overall decrease in burning in the 20th century, linked to the expansion of agriculture, increased livestock grazing, and fire prevention efforts. Prevention
Wildfire prevention refers to the preemptive methods of reducing the risk of fires as well as lessening its severity and spread. North American firefighting policies may permit naturally caused fires to burn to maintain their ecological role, so long as the risks of escape into high-value areas are mitigated. However, prevention policies must consider the role that humans play in wildfires, since, for example, 95% of forest fires in Europe are related to human involvement. Sources of human-caused fire may include arson, accidental ignition, or the uncontrolled use of fire in land-clearing and agriculture such as the slash-and-burn farming in Southeast Asia. Roosevelt initiated a nationwide fire prevention campaign, highlighting the role of human carelessness in forest fires. Other than reducing human infractions, only fuels may be altered to affect future fire risk and behavior. Wildfire prevention programs around the world may employ techniques such as wildland fire use and prescribed or controlled burns. Wildland fire use refers to any fire of natural causes that is monitored but allowed to burn. Controlled burns are fires ignited by government agencies under less dangerous weather conditions. Vegetation may be burned periodically to maintain high species diversity, and frequent burning of surface fuels limits fuel accumulation, thereby reducing the risk of crown fires. Multiple fuel treatments are often needed to influence future fire risks, and wildfire models may be used to predict and compare the benefits of different fuel treatments on future wildfire spread. Additionally, while fuel treatments are typically limited to smaller areas, effective fire management requires the administration of fuels across large landscapes in order to reduce future fire size and severity. Communities in the Philippines also maintain fire lines 5 to 10 meters (16 to 33 ft) wide between the forest and their village, and patrol these lines during summer months or seasons of dry weather. Fuel buildup can result in costly, devastating fires as new homes, ranches, and other development are built adjacent to wilderness areas. Continued growth in fire-prone areas and rebuilding structures destroyed by fires has been met with criticism. For example, while fuel treatments decrease the risk of crown fires, these techniques destroy the habitats of various plant and animal species. Fire lookout towers were used in the United States in the early 1900s and fires were reported using telephones, carrier pigeons, and heliographs. Early satellite-derived fire analyses were hand-drawn on maps at a remote site and sent via overnight mail to the fire manager. During the Yellowstone fires of 1988, a data station was established in West Yellowstone, permitting the delivery of satellite-based fire information in approximately four hours. Currently, public hotlines, fire lookouts in towers, and ground and aerial patrols can be used as a means of early detection of forest fires. Larger, medium-risk areas can be monitored by scanning towers that incorporate fixed cameras and sensors to detect smoke or additional factors such as the infrared signature of carbon dioxide produced by fires. The National Oceanic and Atmospheric Administration's Hazard Mapping System combines remote-sensing data from satellite sources such as Geostationary Operational Environmental Satellite (GOES), Moderate-Resolution Imaging Spectroradiometer (MODIS), and Advanced Very High Resolution Radiometer (AVHRR) for detection of fire and smoke plume locations. Silver iodide can be used to encourage snow fall, while fire retardants and water can be dropped onto fires by unmanned aerial vehicles, planes, and helicopters. Complete fire suppression is no longer an expectation, but the majority of wildfires are often extinguished before they grow out of control. A wildfire's burning front may also change direction unexpectedly and jump across fire breaks. Intense heat and smoke can lead to disorientation and loss of appreciation of the direction of the fire, which can make fires particularly dangerous. For example, during the 1949 Mann Gulch fire in Montana, USA, thirteen smokejumpers died when they lost their communication links, became disorientated, and were overtaken by the fire. Modeling
Wildfire modeling is concerned with numerical simulation of wildfires in order to comprehend and predict fire behavior. Using computational science, wildfire modeling involves the statistical analysis of past fire events to predict spotting risks and front behavior. However, large fires that exceed suppression capabilities are often regarded as statistical outliers in standard analyses, even though fire policies are more influenced by catastrophic wildfires than by small fires.
National Interagency Fire Center USFS BLM CALFIRE CALFIRE Aviation New South Wales Rural Fire Service Country Fire Authority, Victoria Country Fire Service, South Australia
Incident Command System Aerial firefighting Controlled burn Firebreak Fire trail Fire lookout tower Fire-retardant gel Fire fighting foam Fire retardant MAFFS Helicopter bucket Driptorch
An artificially colored satellite view of Africa, with red and yellow markers where fires have been detected.
Ground fires are fed by subterranean roots, duff and other buried organic matter. Ground fires typically burn by smoldering, and can burn slowly for days to months, such as peat fires in Kalimantan and Eastern Sumatra, Indonesia, which resulted from a riceland creation project that unintentionally drained and dried the peat. The ignition of a crown fire, termed crowning, is dependent on the density of the suspended material, canopy height, canopy continuity, and sufficient surface and ladder fires in order to reach the tree crowns. For example, ground-clearing fires lit by humans can spread into the Amazon rain forest, damaging ecosystems not particularly suited for heat or arid conditions.
Smoke trail from a fire seen while looking towards Dargo from Swifts Creek, Victoria, Australia, 11 January 2007
See also: Control of fire by early humans, Deforestation#Historical causes, Environmental history, History of firefighting,and List of wildfires
Drawing of a grizzly bear with human features. The increase in vegetation density was attributed to fire prevention efforts since 1895. National Wildfire Coordinating Group Fireline Handbook, Appendix B: Fire Behavior; Standard Fire Behavior Fuel Models: A Comprehensive Set for Use with Rothermels Surface Fire Spread Model. Modeling Large Forest Fires as Extreme Events. Automatic remote surveillance system for the prevention of forest fires. Community Involvement in and Management of Forest Fires in South East Asia;
Fire intensity, fire severity and burn severity: a brief review and suggested usage. The impact of fire suppression, vegetation, and weather on the area burned by lightning-caused forest fires in Ontario. National Wildfire Coordinating Group Communicator's Guide for Wildland Fire Management: Fire Education, Prevention, and Mitigation Practices, Wildland Fire Overview. A Burning Story: The Role of Fire in the History of Life. Holocene fire history of middle boreal pine forest sites in eastern Finland. Active Fire Detection for Fire Emergency Management: Potential and Limitations for the Operational Use of Remote Sensing. Use of a Deterministic Fire Growth Model to Test Fuel Treatments. See WERC Highlights April 2008)
National Interagency Fire Center: National Wildfire Coordinating Group Communicator's Guide For Wildland Fire Management Table of Contents
National Oceanic and Atmospheric Administration (NOAA): Economic Costs of Wildfires
Wildland Fire Operations Research Group (WFORG): Detection Workshop Presentations
Firefighter Fire chief Fire marshal Fire Master Firefighter Assist and Search Team Fire Police Handcrews Helitack Hotshots Smokejumper Station officer Volunteer fire department
Glossary of firefighting equipment Bunker gear Escape chair Fire apparatus Fire bike Fire chief's vehicle Fire extinguisher Fire hose Fire hydrant Fire retardant Fire station Fireman's switch Flame retardant Hard suction hose Heat detector List of fire-retardant materials Nomex PASS Rescue pumper SCBA Siren Smoke detector Splash suit Super Scooper Thermal imaging camera
Glossary of firefighting terms Glossary of wildland fire terms Aerial firefighting Dead Man Zone Draft Fire classes Fire control Fire safety Fire triangle Fireman's carry Firewall Flash fire Forcible entry Gaseous fire suppression Master stream Stop, drop and roll Structure fire Two-in, two-out Ventilation Wetdown Wildfire Wildfire suppression
Fire engine red Firefighting worldwide History of firefighting Incident Command System International Association of Fire Fighters International Firefighters' Day List of historic fires List of firefighting films London Fire Brigade Museum National Fire Incident Reporting System National Fire Protection Association Saint Florian World Police and Fire Games
Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. The fire can be extinguished by any of the following:
In contrast, fire is intensified by increasing the overall rate of combustion. Typical temperatures of fires and flames
The temperature of flames with carbon particles emitting light can be assessed by their color:
The fossil record of fire first appears with the establishment of a land-based flora in the Middle Ordovician period, 470 million years ago, permitting the accumulation of oxygen in the atmosphere as never before, as the new hordes of land plants pumped it out as a waste product. Fire has also been used for centuries as a method of torture and execution, as evidenced by death by burning as well as torture devices such as the iron boot which could be filled with water, oil, or even lead and then heated over an open fire to the agony of the wearer. These fires were typically controlled burns or "cool fires", as opposed to uncontrolled "hot fires" which damage the soil. Hunter-gatherer groups around the world have been noted as using grass and forest fires to injure their enemies and destroy their ability to find food, so it can be assumed that fire has been used in warfare for as long as humans have had the knowledge to control it. In the latter war, incendiary bombs were used by Axis and Allies alike, notably on Tokyo, Rotterdam, London, Hamburg and, notoriously, at Dresden, in the latter two cases firestorms were deliberately caused in which a ring of fire surrounding each city was drawn inward by an updraft caused by a central cluster of fires. Protection and prevention
Fire fighting services are provided in most developed areas to extinguish or contain uncontrolled fires. Trained firefighters use fire apparatus, water supply resources such as water mains and fire hydrants or they might use A and B class foam depending on what is feeding the fire. Fire prevention also includes education to teach people how to avoid causing fires. Model building codes require passive fire protection and active fire protection systems to minimize damage resulting from a fire. The most common form of active fire protection is fire sprinklers.
moebuildingcontrol.co.uk - UK Guidance on fire safety codes and fire engineering