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{{Short description|Rapid and hot oxidation of a material}} {{Other uses}} {{pp-semi-protected|small=yes}} {{Pp-move-indef}} {{CS1 config|mode=cs1}} {{multiple image |align=right |direction=vertical |width=250 |image1=Large bonfire.jpg |caption1=An outdoor wood fire |image2=Feu-de-paille-couverture.ogg |caption2=The ignition and extinguishing of a pile of wood shavings |image3= |caption3=A beach [[bonfire]] on [[Guy Fawkes Night]] }} '''Fire''' is the rapid [[oxidation]] of a [[fuel]] in the [[exothermic]] chemical process of [[combustion]], releasing [[heat]], [[light]], and various reaction [[Product (chemistry)|products]].<ref>{{cite web |title=Glossary of Wildland Fire Terminology |date=October 2007 |url=http://www.nwcg.gov/pms/pubs/glossary/pms205.pdf |journal= |pages=70 |access-date=2008-12-18 |archive-url=https://web.archive.org/web/20080821230940/http://www.nwcg.gov/pms/pubs/glossary/pms205.pdf |url-status=deviated |publisher=National Wildfire Coordinating Group |archive-date=2008-08-21}}</ref>{{efn|Slower oxidative processes like [[rusting]] or [[digestion]] are not included by this definition.}} [[Flame]]s, the most visible portion of the fire, are produced in the combustion reaction when the fuel reaches its [[ignition point]] temperature. Flames from [[hydrocarbon]] fuels consist primarily of carbon dioxide, water vapor, oxygen, and nitrogen. If hot enough, the gases may become ionized to produce [[Plasma (physics)|plasma]].<ref>{{cite journal |last1=Fukuyama |first1=Takao |last2=Mukai |first2=Nodoka |last3=Togawa |first3=Gaku |title=Dynamic behaviours of a flame as plasma in a strong electric field |journal=Scientific Reports |date=1 November 2019 |volume=9 |issue=1 |pages=15811 |doi=10.1038/s41598-019-50537-x|hdl=10069/39515 |hdl-access=free }}</ref> The [[color]] and [[Intensity (heat transfer)|intensity]] of the flame depend on the type of fuel and composition of the surrounding gases.<ref>{{Cite web|url=http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/flame.html|title=Flame Colors as Chemical Indicators|archive-url=https://web.archive.org/web/20141007091024/http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/flame.html|archive-date=2014-10-07|url-status=dead|access-date=2014-04-01}}</ref> Fire, in its most common form, has the potential to result in [[conflagration]], which can lead to permanent physical damage. It directly impacts land-based ecological systems worldwide. The positive effects of fire include stimulating plant growth and maintaining ecological balance. Its negative effects include hazards to life and property, atmospheric pollution, and water contamination.<ref>{{cite journal | last1=Lentile | first1=Leigh B. | last2=Holden | first2=Zachary A. | last3=Smith | first3=Alistair M. S. | last4=Falkowski | first4=Michael J. | last5=Hudak | first5=Andrew T. | last6=Morgan | first6=Penelope | last7=Lewis | first7=Sarah A. | last8=Gessler | first8=Paul E. | last9=Benson | first9=Nate C | title=Remote sensing techniques to assess active fire characteristics and post-fire effects | year=2006 | journal=International Journal of Wildland Fire | issue=15 | volume=3 | pages=319–345 | doi=10.1071/WF05097 | s2cid=724358 }}</ref> When fire removes [[Soil erosion#Vegetative cover|protective vegetation]], heavy [[rain]]fall can cause [[Soil erosion#Rainfall and surface runoff|soil erosion]].<ref>{{cite journal | last1 = Morris | first1 = S. E. | last2 = Moses | first2 = T. A. | year = 1987 | title = Forest Fire and the Natural Soil Erosion Regime in the Colorado Front Range | journal = Annals of the Association of American Geographers | volume = 77 | issue = 2| pages = 245–54 | doi=10.1111/j.1467-8306.1987.tb00156.x |issn=0004-5608 }}</ref> The burning of vegetation releases [[nitrogen]] into the atmosphere, unlike other plant nutrients such as [[potassium]] and [[phosphorus]] which remain in the [[Wood ash|ash]] and are quickly recycled into the soil.<ref>{{Cite news |date=1990-08-14 |title=SCIENCE WATCH; Burning Plants Adding to Nitrogen |language=en-US |work=The New York Times |url=https://www.nytimes.com/1990/08/14/science/science-watch-burning-plants-adding-to-nitrogen.html |access-date=2023-11-02 |issn=0362-4331 |archive-date=2024-05-27 |archive-url=https://web.archive.org/web/20240527111406/https://www.nytimes.com/1990/08/14/science/science-watch-burning-plants-adding-to-nitrogen.html |url-status=live }}</ref><ref>{{Cite web |date=2019-11-12 |title=How Do Wildfires Affect Soil? - Applied Earth Sciences |url=https://aessoil.com/how-do-wildfires-affect-soil/ |access-date=2023-11-02 |language=en-US |archive-date=2024-05-27 |archive-url=https://web.archive.org/web/20240527111411/https://aessoil.com/how-do-wildfires-affect-soil/ |url-status=live }}</ref> This loss of nitrogen produces a long-term reduction in the fertility of the soil, though it can be recovered by ''[[nitrogen-fixing]]'' plants such as [[clover]], [[pea]]s, and [[bean]]s; by decomposition of animal waste and corpses, and by natural phenomena such as [[lightning]]. Fire is one of the four [[Fire (classical element)|classical elements]] and has been used by humans in [[fire worship|rituals]], in agriculture for clearing land, for cooking, generating heat and light, for signaling, propulsion purposes, [[smelting]], [[forging]], [[incineration]] of waste, [[cremation]], and as a weapon or mode of destruction. Various technologies and strategies have been devised to [[Fire prevention|prevent]], manage, [[Fire protection|mitigate]], and extinguish fires, with professional [[firefighter]]s playing a leading role. == Etymology == The word ''fire'' comes from [[Old English]] {{lang|ags|fȳr}} and has cognates in many [[Germanic languages]] and other [[Indo-European languages]].<ref name=Kroonen>{{cite book|last=Kroonen|first=Guus|date=2013|title=Etymological Dictionary of Proto-Germanic|location=Leiden|publisher=Koninklijke Brill NV|page=151|isbn=978-90-04-18340-7}}</ref> The [[Proto-Germanic]] nominative form is reconstructed as {{lang|gem-x-proto|fōr}}, descending from [[Proto-Indo-European]] {{lang|ine-x-proto|péh<sub>2</sub>wr}}.<ref name=Kroonen /> An alternative spelling existed in [[Middle English]]: {{lang|enm|fier}}; still preserved in ''fiery''.<ref>{{Cite web|title=fire|url=https://www.etymonline.com/word/fire|access-date=2025-02-12|website=Online Etymological Dictionary|language=en|archive-date=2025-01-18|archive-url=https://web.archive.org/web/20250118141346/http://www.etymonline.com/word/fire|url-status=live}}</ref> The word ''ignite'' is derived from the classical [[Latin]] ''ignis'' meaning fire.<ref>{{cite web | title=Origin and history of ''ignite'' | first=Douglas | last=Harper | website=etymonline – online etymology dictionary | url=https://www.etymonline.com/word/ignite | access-date=2025-05-24 }}</ref> The Greek term for fire, ''pyr'', is used in words such as [[pyroclastic]] or [[pyrotechnic]].<ref>{{cite web | title=Origin and history of ''pyro''- | first=Douglas | last=Harper | website=etymonline – online etymology dictionary | url=https://www.etymonline.com/word/pyro- | access-date=2025-05-24 }}</ref> == History == === Fossil record === {{Main|Fossil record of fire}} The fossil record of fire first appears with the establishment of a land-based flora in the [[Middle Ordovician]] period, {{ma|470}}.<ref name="Wellman2000">{{cite journal |last1=Wellman |first1=C. H. |last2=Gray |first2=J. |year=2000 |title=The microfossil record of early land plants |journal=Philos Trans R Soc Lond B Biol Sci |volume=355 |issue=1398 |pages=717–31; discussion 731–2 |doi=10.1098/rstb.2000.0612 |pmc=1692785 |pmid=10905606}}</ref> These land plants contributed large amounts of [[oxygen]] to the atmosphere when they released it as a waste product. When this concentration rose above 13%, it permitted the possibility of [[wildfire]].<ref name="Jones1991">{{cite journal |last1=Jones |first1=Timothy P. |last2=Chaloner |first2=William G. |year=1991 |title=Fossil charcoal, its recognition and palaeoatmospheric significance |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=97 |issue=1–2 |pages=39–50 |bibcode=1991PPP....97...39J |doi=10.1016/0031-0182(91)90180-Y}}</ref> Wildfire is first recorded in the [[Late Silurian]] fossil record, {{Ma|420}}, by fossils of [[charcoal|charred]] plants.<ref name="DoiGMissing">{{cite journal |last1=Glasspool |first1=I. J. |last2=Edwards |first2=D. |last3=Axe |first3=L. |year=2004 |title=Charcoal in the Silurian as evidence for the earliest wildfire |journal=Geology |volume=32 |issue=5 |pages=381–383 |bibcode=2004Geo....32..381G |doi=10.1130/G20363.1}}</ref><ref name="Scott2006">{{cite journal |last1=Scott |first1=A. C. |last2=Glasspool |first2=I. J. |year=2006 |title=The diversification of Paleozoic fire systems and fluctuations in atmospheric oxygen concentration |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=103 |issue=29 |pages=10861–5 |bibcode=2006PNAS..10310861S |doi=10.1073/pnas.0604090103 |pmc=1544139 |pmid=16832054 |doi-access=free}}</ref> Apart from a controversial gap in the [[Late Devonian]], charcoal is present ever since.<ref name="Scott2006" /> The level of atmospheric oxygen is closely correlated with the amount of charcoal in the fossil record, clearly pointing to oxygen as the key factor in the prevalence of wildfire.<ref name="Bowman2009">{{cite journal |last1=Bowman |first1=D. M. J. S. |last2=Balch |first2=J. K. |last3=Artaxo |first3=P. |last4=Bond |first4=W. J. |last5=Carlson |first5=J. M. |last6=Cochrane |first6=M. A. |last7=d'Antonio |first7=C. M. |last8=Defries |first8=R. S. |last9=Doyle |first9=J. C. |last10=Harrison |first10=S. P. |last11=Johnston |first11=F. H. |last12=Keeley |first12=J. E. |last13=Krawchuk |first13=M. A. |last14=Kull |first14=C. A. |last15=Marston |first15=J. B. |year=2009 |title=Fire in the Earth system |journal=Science |volume=324 |issue=5926 |pages=481–4 |bibcode=2009Sci...324..481B |doi=10.1126/science.1163886 |pmid=19390038 |s2cid=22389421 |last16=Moritz |first16=M. A. |last17=Prentice |first17=I. C. |last18=Roos |first18=C. I. |last19=Scott |first19=A. C. |last20=Swetnam |first20=T. W. |last21=Van Der Werf |first21=G. R. |last22=Pyne |first22=S. J. |url=https://resolver.caltech.edu/CaltechAUTHORS:20090707-150808418 |access-date=2024-01-26 |archive-date=2024-05-27 |archive-url=https://web.archive.org/web/20240527111415/https://authors.library.caltech.edu/records/m358a-0c317 |url-status=live }}</ref> Fire also became more abundant when grasses became the dominant component of many ecosystems, around {{Ma|6|7}},<ref name="Retallack1997">{{cite journal |last1=Retallack |first1=Gregory J. |date=1997 |title=Neogene expansion of the North American prairie |journal=PALAIOS |volume=12 |issue=4 |pages=380–90 |bibcode=1997Palai..12..380R |doi=10.2307/3515337 |jstor=3515337}}</ref> providing excellent [[tinder]] for more rapid spread of fire.<ref name="Bowman2009" /> This widespread emergence of wildfire may have initiated a [[positive feedback]] process, whereby they produced a warmer, drier climate more conducive to fire.<ref name="Bowman2009" /> === Human control === The period of history characterized by the influence of human-caused fire activity on Earth has been dubbed the [[pyrocene]]. This epoch includes the burning of [[fossil fuel]]s, especially for technological uses.<ref>{{cite web | title=Human use of fire has produced an era of uncontrolled burning: Welcome to the Pyrocene | first=Stephen | last=Pyne | date=February 10, 2025 | publisher=Modern Sciences | url=https://modernsciences.org/human-use-fire-era-uncontrolled-burning-pyrocene-february-2025/ | access-date=2025-02-26 }}</ref> ==== Early human control ==== {{Main|Control of fire by early humans}} <mapframe text="Archaeological sites with early human fire use from the [https://www.roceeh.uni-tuebingen.de/roadweb ROAD database] (CC BY-SA 4.0 ROCEEH)" width="400", height="300"> { "type": "ExternalData", "service": "page", "title": "ROCEEH/Early_fire.map" } </mapframe> The ability to control fire was a dramatic change in the habits of early humans.<ref>{{cite journal |last1=Gowlett |first1=J. A. J. |title=The discovery of fire by humans: a long and convoluted process |journal=[[Philosophical Transactions of the Royal Society B|Philosophical Transactions of the Royal Society B: Biological Sciences]] |date=2016 |volume=371 |issue=1696 |pages=20150164 |doi=10.1098/rstb.2015.0164 |pmid=27216521 |pmc=4874402 |doi-access=free}}</ref> [[Making fire]] to generate heat and light made it possible for people to [[cooking|cook]] food, simultaneously increasing the variety and availability of nutrients and reducing disease by killing pathogenic microorganisms in the food.<ref>{{Cite journal |last1=Gowlett |first1=J. A. J. |last2=Wrangham |first2=R. W. |date=2013 |title=Earliest fire in Africa: towards the convergence of archaeological evidence and the cooking hypothesis |journal=Azania: Archaeological Research in Africa |volume=48 |issue=1 |pages=5–30 |doi=10.1080/0067270X.2012.756754 |s2cid=163033909}}</ref> The heat produced would also help people stay warm in cold weather, enabling them to live in cooler climates. Fire also kept nocturnal predators at bay. Evidence of occasional cooked food is found from {{Ma|1.0}},<ref>{{cite journal |last1=Kaplan |first1=Matt |year=2012 |title=Million-year-old ash hints at origins of cooking |url=https://www.nature.com/news/million-year-old-ash-hints-at-origins-of-cooking-1.10372 |url-status=live |journal=Nature |doi=10.1038/nature.2012.10372 |s2cid=177595396 |archive-url=https://web.archive.org/web/20191001174313/http://www.nature.com/news/million-year-old-ash-hints-at-origins-of-cooking-1.10372 |archive-date=1 October 2019 |access-date=25 August 2020|url-access=subscription }}</ref> suggesting it was used in a controlled fashion.<ref>{{cite web |last=O'Carroll |first=Eoin |date=5 April 2012 |title=Were Early Humans Cooking Their Food a Million Years Ago? |url=https://abcnews.go.com/Technology/early-humans-cooking-food-million-years-ago/story?id=16080804#.T4IyWe1rFDI |url-status=live |archive-url=https://web.archive.org/web/20200204145413/https://abcnews.go.com/Technology/early-humans-cooking-food-million-years-ago/story?id=16080804#.T4IyWe1rFDI |archive-date=4 February 2020 |access-date=10 January 2020 |work=ABC News |quote=Early humans harnessed fire as early as a million years ago, much earlier than previously thought, suggests evidence unearthed in a cave in South Africa.}}</ref><ref>{{cite journal | first1=Francesco | last1=Berna | first2=Paul | last2=Goldberg | first3=Liora Kolska | last3=Horwitz | first4=Michael | last4=Chazan |date=May 15, 2012 |title=Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa |journal=PNAS |volume=109 |issue=20 |pages=E1215–E1220 |doi=10.1073/pnas.1117620109 |pmc=3356665 |pmid=22474385 |doi-access=free}}</ref> Other sources put the date of regular use at 400,000 years ago.<ref name="Bowman2009b">{{cite journal |last1=Bowman |first1=D. M. J. S. |last2=Balch |first2=J. K. |last3=Artaxo |first3=P. |last4=Bond |first4=W. J. |last5=Carlson |first5=J. M. |last6=Cochrane |first6=M. A. |last7=d'Antonio |first7=C. M. |last8=Defries |first8=R. S. |last9=Doyle |first9=J. C. |last10=Harrison |first10=S. P. |last11=Johnston |first11=F. H. |last12=Keeley |first12=J. E. |last13=Krawchuk |first13=M. A. |last14=Kull |first14=C. A. |last15=Marston |first15=J. B. |year=2009 |title=Fire in the Earth system |journal=Science |volume=324 |issue=5926 |pages=481–84 |bibcode=2009Sci...324..481B |doi=10.1126/science.1163886 |pmid=19390038 |s2cid=22389421 |last16=Moritz |first16=M. A. |last17=Prentice |first17=I. C. |last18=Roos |first18=C. I. |last19=Scott |first19=A. C. |last20=Swetnam |first20=T. W. |last21=Van Der Werf |first21=G. R. |last22=Pyne |first22=S. J. |url=https://resolver.caltech.edu/CaltechAUTHORS:20090707-150808418 |access-date=2024-01-26 |archive-date=2024-05-27 |archive-url=https://web.archive.org/web/20240527111415/https://authors.library.caltech.edu/records/m358a-0c317 |url-status=live }}</ref> Evidence becomes widespread around 50 to 100 thousand years ago, suggesting regular use from this time; resistance to [[air pollution]] started to evolve in human populations at a similar point in time.<ref name="Bowman2009b" /> The use of fire became progressively more sophisticated, as it was used to create charcoal and to control wildlife from tens of thousands of years ago.<ref name="Bowman2009b" /> [[File:Potjiekos over a fire.gif|thumb|Here, food is cooked in a [[Potjie|cauldron]] above fire in [[South Africa]].]] By the [[Neolithic Revolution]], during the introduction of grain-based agriculture, people all over the world used fire as a tool in [[landscape]] management. These fires were typically [[controlled burn]]s or "cool fires", as opposed to uncontrolled "hot fires", which damage the soil. Hot fires destroy plants and animals, and endanger communities.<ref>{{cite book |last=Pyne |first=Stephen J. |title=Advances in Historical Ecology |date=1998 |publisher=University of Columbia Press |isbn=0-231-10632-7 |editor-last=Balée |editor-first=William |series=Historical Ecology Series |pages=78–84 |chapter=Forged in Fire: History, Land and Anthropogenic Fire |chapter-url=https://books.google.com/books?id=A5cUpbvNcH4C&pg=PA76 }}</ref> This is especially a problem in the forests of today where traditional burning is prevented in order to encourage the growth of timber crops. Cool fires are generally conducted in the spring and autumn. They clear undergrowth, burning up [[biomass]] that could trigger a hot fire should it get too dense. They provide a greater variety of environments, which encourages game and plant diversity. For humans, they make dense, impassable forests traversable.<ref>{{cite journal | title=Fire as a forest management tool: prescribed burning in the southern United States | last1=Wade | first1=D. D. | last2=Lundsford | first2=J. | year=1990 | journal=Unasylva | volume=41 | issue=3 | pages=28–38 | url=https://www.fao.org/4/t9500e/t9500e07.htm | access-date=2025-02-25 }}</ref> Another human use for fire in regards to landscape management is its use to clear land for agriculture. [[Slash-and-burn]] agriculture is still common across much of tropical Africa, Asia and South America. For small farmers, controlled fires are a convenient way to clear overgrown areas and release nutrients from standing vegetation back into the soil.<ref name="blogs.ei.columbia.edu">{{cite web |last=Krajick |first=Kevin |date=16 November 2011 |title=Farmers, Flames and Climate: Are We Entering an Age of 'Mega-Fires'? – State of the Planet |url=http://blogs.ei.columbia.edu/2011/11/16/farmers-flames-and-climate-are-we-entering-an-age-of-mega-fires/ |url-status=live |archive-url=https://web.archive.org/web/20120526005052/http://blogs.ei.columbia.edu/2011/11/16/farmers-flames-and-climate-are-we-entering-an-age-of-mega-fires/ |archive-date=2012-05-26 |access-date=2012-05-23 |publisher=Columbia Climate School}}</ref> However, this useful strategy is also problematic. Growing population, fragmentation of forests and warming climate are making the earth's surface more prone to ever-larger escaped fires. These harm ecosystems and human infrastructure, cause health problems, and send up spirals of carbon and soot that may encourage even more warming of the atmosphere – and thus feed back into more fires. Globally today, as much as 5 million square kilometres – an area more than half the size of the United States – burns in a given year.<ref name="blogs.ei.columbia.edu" /> ==== Later human control ==== {{multiple image | align = right | total_width = 400 | image1 = The Great Fire of London, with Ludgate and Old St. Paul's.JPG | alt1 = | image2 = Royal Air Force Bomber Command, 1942-1945. CL3400.jpg | alt2 = The Lyceum in 1861 | footer = [[The Great Fire of London]] (1666) and [[Hamburg]] after four [[fire-bombing]] raids in July 1943, which killed an estimated 50,000 people<ref>"[http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/03/europe_german_destruction/html/4.stm In Pictures: German destruction] {{Webarchive|url=https://web.archive.org/web/20191213141457/http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/03/europe_german_destruction/html/4.stm |date=2019-12-13 }}". [[BBC News]].</ref> }} Throughout much of history, cultures attempted to explain nature and the properties of matter by proposing a set of four (or five) [[classical element]]s, of which [[Fire (classical element)|fire formed one of the components]]. As scientific understanding developed following the [[Middle Ages]], this philosophy was replaced by a set of chemical elements and their interactions. Instead, the classical elements found an equivalency in the [[State of matter|states of matter]]: solid, liquid, gas, and plasma.<ref>{{cite journal | title=The Origin of the Elements | last=Penzias | first=A. A. | author-link=Arno Allan Penzias | journal=Science | date=August 1979 | volume=205 | issue=4406 | pages=549–554 | doi=10.1126/science.205.4406.549 | bibcode=1979Sci...205..549P }}</ref> During the 17th century, a study of combustion was made by [[Jan Baptist van Helmont]] who discovered that burning charcoal released a ''gas sylvestris'', or wild spirit.<ref name=Dolman_2023>{{cite book | chapter=The discovery of the Carbon Dioxide molecule | first=Han | last=Dolman | date=March 2023 | pages=37–61 | title=Carbon Dioxide through the Ages: From wild spirit to climate culprit | isbn=9780198869412 | publisher=Oxford University Press | doi=10.1093/oso/9780198869412.003.0003 }}</ref> This was subsequently incorporated into [[Phlogiston theory]] by [[Johann Joachim Becher]] in 1667; a concept that would dominate alchemical thinking for nearly two centuries.<ref>{{cite web | title=Combustion | work=Science Encyclopedia | url=https://science.jrank.org/pages/1628/Combustion-History.html | access-date=2025-03-07 }}</ref> It was [[Antoine Lavoisier]] who demonstrated that combustion did not involve the release of a substance, but rather something was being taken up.<ref name=Dolman_2023/> In 1777, Lavoisier proposed a new theory of combustion based on the reaction of a material with a component of air, which he termed oxygène. By 1791, Lavoisier's chemistry concepts had been widely adopted by young scientists, and Phlogiston theory was rejected.<ref>{{cite web | title=The Chemical Revolution of Antoine-Laurent Lavoisier | series=International Historic Chemical Landmark | publisher=[[American Chemical Society]] | url=https://www.acs.org/education/whatischemistry/landmarks/lavoisier.html | access-date=2025-03-07 }}</ref> Fire has been used for centuries as a method of torture and execution,<ref>{{cite conference | last1=Petaros | first1=A. | last2=Borrini | first2=M. | last3=Josip | first3=A. | year=2009 | title=The history of fire and torture – fire in crimes committed against the integrity of life and health | conference=V Meeting of the International Society for the History of Medicine | pages=92-92 | url=https://www.croris.hr/crosbi/publikacija/prilog-skup/554979 | access-date=2025-02-25 }}</ref> as evidenced by [[death by burning]] as well as torture devices such as the [[Boot (torture)|iron boot]],<ref>{{cite journal | title=Torture under English Law | first=Ernest G. | last=Black | journal=University of Pennsylvania Law Review and American Law Register | volume=75 | issue=4 | date=February 1927 | pages=344–348 | doi=10.2307/3307506 | jstor=3307506 }}</ref> which could be heated over an open fire to the agony of the wearer.<ref>{{cite journal | title=The Use and Forms of Judicial Torture in England and Scotland | first=R. D. | last=Melville | journal=The Scottish Historical Review | volume=2 | issue=7 | date=April 1905 | pages=225–248 | jstor=25517609 }} In particular, see p. 238.</ref> There are numerous modern applications of fire. In its broadest sense, fire is used by nearly every human being on Earth in a controlled setting every day. Users of [[internal combustion]] vehicles employ fire every time they drive. Thermal [[power station]]s provide [[electricity]] for a large percentage of humanity by igniting fuels such as [[coal]], [[oil]] or [[natural gas]], then using the resultant heat to boil water into [[steam]], which then drives [[turbine]]s.<ref>{{cite web | title=Why Fire Is the Greatest Tool of All Time | first=Vince | last=Guerrieri | date=February 17, 2020 | work=Popular Mechanics | publisher=Hearst Digital Media | url=https://www.popularmechanics.com/home/tools/a30456620/fire-greatest-tool/ | access-date=2025-02-26 }}</ref> ==== Use in war ==== The use of fire in [[Conventional warfare|warfare]] has a long [[military history|history]]. Fire was the basis of all [[early thermal weapons]], including [[incendiary device]]s, heated projectiles, and the use of smoke. This class of weapons was particularly evident during naval battles and [[siege warfare]]. The [[Byzantine Empire|Byzantine]] fleet used [[Greek fire]] to attack ships and men.<ref>{{cite journal | title=Fire and Brimstone: SO<sub>2</sub> as a Chemical Weapon in History | first1=Matthew D. | last1=Turner | first2=Jason | last2=Sapp | journal=Military Medicine | volume=188 | issue=11–12 | date=November 2023 | pages=286–288 | doi=10.1093/milmed/usad160 | doi-access=free }}</ref><ref>{{cite web | title=Incendiary Weapons - History | website=GlobalSecurity.org | url=https://www.globalsecurity.org/military/systems/munitions/incendiary-history.htm | access-date=2025-02-26 }}</ref><ref>{{cite journal | title=Chemical warfare in the middle ages. Kallinikos' 'prepared fire' | first=Nicholas D. | last=Cheronis | journal=Journal of Chemical Education | volume=14 | issue=8 | page=360 | date=August 1, 1937 | doi=10.1021/ed014p360 | bibcode=1937JChEd..14..360C }}</ref><ref name=McNab_2015>{{cite book | title=The Flamethrower | first=Chris | last=McNab | publisher=Bloomsbury Publishing | year=2015 | isbn=9781472809032 | page=6 | url=https://books.google.com/books?hl=en&lr=&id=onyXCwAAQBAJ&pg=PA6&v=onepage }}</ref> The invention of [[gunpowder]] in China led to the [[fire lance]], a flame-thrower weapon dating to around 1000 CE which was a precursor to [[History of the firearm|projectile weapons driven by burning gunpowder]].<ref>{{cite journal | title=Cathayan Arrows and Meteors: The Origins of Chinese Rocketry | journal=Journal of Chinese Military History | first=Stephen G. | last=Haw | year=2013 | volume=2 | issue=1 | pages=28-42 | doi=10.1163/22127453-12341243 }}</ref> The earliest modern [[flamethrower]]s were used by infantry in the [[World War I|First World War]], first used by German troops against entrenched French troops near Verdun in February 1915.<ref>{{Cite web | title=Flamethrower in action | url=https://nzhistory.govt.nz/media/photo/flamethrower-action | access-date=2023-11-02 | website=nzhistory.govt.nz | language=en | archive-date=2024-05-27 | archive-url=https://web.archive.org/web/20240527111922/https://nzhistory.govt.nz/media/photo/flamethrower-action | url-status=live }}</ref> They were later successfully mounted on armoured vehicles in the Second World War.<ref>{{cite book | title=Churchill Crocodile Flamethrower | first=David | last=Fletcher | volume=136 | series=New Vanguard | pages=4–6 | publisher=Bloomsbury Publishing | year=2012 | isbn=9781780968032 | url=https://books.google.com/books?id=dJ2jCwAAQBAJ&pg=PA4 }}</ref> Hand-thrown [[incendiary bombs]] improvised from glass bottles, later known as [[Molotov cocktails]], were deployed during the [[Spanish Civil War]] in the 1930s.<ref>{{cite journal | title=Anionic markers for the forensic identification of Chemical Ignition Molotov Cocktail composition | first1=C. | last1=Martín-Alberca | first2=J. L. | last2=Ferrando | first3=C. | last3=García-Ruiz | journal=Science & Justice | volume=53 | issue=1 | date=March 2013 | pages=49–54 | doi=10.1016/j.scijus.2012.11.004 }}</ref> During that war, incendiary bombs were deployed against [[Bombing of Guernica|Guernica]] by Fascist [[Aviazione Legionaria|Italian]] and Nazi [[Condor Legion|German]] air forces that had been created specifically to support [[Francisco Franco|Franco's]] [[Francoist Spain|Nationalists]].<ref>{{cite journal | title=Xabier Irujo. Gernika, 1937: The Market Day Massacre | first=Ian | last=Patterson | location=Reno | publisher=University of Nevada Press | journal=The American Historical Review | volume=122 | issue=1 | date=February 1, 2017 | pages=263–264 | doi=10.1093/ahr/122.1.263 }}</ref> Incendiary bombs were dropped by [[Axis Powers|Axis]] and [[Allies of World War II|Allies]] during the Second World War, notably on [[Coventry Blitz|Coventry]], [[Bombing of Tokyo (10 March 1945)|Tokyo]], [[German bombing of Rotterdam|Rotterdam]], [[The Blitz|London]], [[Bombing of Hamburg in World War II|Hamburg]] and [[Bombing of Dresden in World War II|Dresden]]. In the latter two cases, [[firestorm]]s were deliberately caused in which a ring of fire surrounding each city was drawn inward by an [[Vertical draft|updraft]] created by a central cluster of fires.<ref name="BarashWebel2008">{{cite book | first1=David P. | last1=Barash | first2=Charles P. | last2=Webel |url=https://books.google.com/books?id=eeze4_wGViMC |title=Peace and Conflict Studies |date=10 July 2008 |publisher=SAGE |isbn=978-1-4129-6120-2 |pages=365 }}</ref> The United States Army Air Force extensively used incendiaries against Japanese targets in the latter months of the war, devastating entire cities constructed primarily of wood and paper houses. The incendiary fluid [[napalm]] was used in July 1944, towards the end of the [[World War II|Second World War]], although its use did not gain public attention until the [[Vietnam War]].<ref>{{Cite journal |last=Guillaume |first=Marine |date=2016-12-01 |title=Napalm in US Bombing Doctrine and Practice, 1942-1975 |url=https://apjjf.org/-Marine-Guillaume/4983/article.pdf |journal=The Asia-Pacific Journal |volume=14 |issue=23 |archive-url=https://web.archive.org/web/20200904095842/https://apjjf.org/-Marine-Guillaume/4983/article.pdf |archive-date=2020-09-04 |url-status=live }}</ref> ==== Productive use for energy ==== [[File:ChineseCoalPower.jpg|thumb|A [[Fossil fuel power plant|coal-fired power station]] in China]] Burning [[fuel]] converts chemical energy into heat energy; [[wood]] has been used as fuel since [[prehistory]].<ref>{{cite book | title=Science for All Americans | first1=F. James | last1=Rutherford | first2=Andrew | last2=Ahlgren | year=1991 | pages=114–118 | publisher=Oxford University Press | isbn=9780195361865 | url=https://www.google.com/books/edition/Science_for_All_Americans/LKadiKAUljEC?gbpv=1&pg=PA114 }}</ref> The [[International Energy Agency]] states that nearly 80% of the world's power has consistently come from [[fossil fuel]]s such as [[petroleum]], [[natural gas]], and [[coal]] in the past decades.<ref>{{cite web | date=October 2022 | url=https://www.iea.org/reports/world-energy-outlook-2022 | title=World Energy Outlook 2022 | publisher=IEA | archive-url=https://web.archive.org/web/20221027232322/https://www.iea.org/reports/world-energy-outlook-2022 | archive-date=2022-10-27 }}</ref> The fire in a [[power station]] is used to heat water, creating steam that drives [[turbine]]s. The turbines then spin an [[electric generator]] to produce electricity.<ref>{{Cite web |title=How electricity is generated |url=https://www.eia.gov/energyexplained/electricity/how-electricity-is-generated.php |access-date=2023-11-02 |website=U.S. Energy Information Administration }}</ref> Fire is also used to provide [[work (physics)|mechanical work]] directly by [[thermal expansion]], in both [[external combustion engine|external]] and [[internal combustion engine]]s.{{cn|date=May 2025}} The [[Burn|unburnable]] solid remains of a combustible material left after a fire is called ''clinker'' if its [[melting point]] is below the flame temperature, so that it fuses and then solidifies as it cools, and ''ash'' if its melting point is above the flame temperature.<ref>{{cite web |title=Clinker Formation in Biomass Boiler: What Is It and How To Prevent It |url=https://azwood.co.nz/articles/clinker-formation-in-biomass-boiler-what-is-it-and-how-to-prevent-it |publisher=Azwood |accessdate=2025-05-02}}</ref> == Physical properties == === Chemistry === {{Main|Combustion}} [[File:Combustion reaction of methane.jpg|thumb|The balanced chemical equation for the [[combustion]] of [[methane]], a [[hydrocarbon]]]] Fire is a chemical process in which a [[fuel]] and an [[oxidizing agent]] react, yielding [[carbon dioxide]] and [[water]].<ref name="newscientist">{{cite web|title=What is fire?|url=https://www.newscientist.com/question/what-is-fire/|work=New Scientist|access-date=November 5, 2022|archive-date=February 2, 2023|archive-url=https://web.archive.org/web/20230202012338/https://www.newscientist.com/question/what-is-fire/|url-status=live}}</ref> This process, known as a [[combustion reaction]], does not proceed directly and involves [[Reaction intermediate|intermediates]].<ref name="newscientist" /> Although the oxidizing agent is typically [[oxygen]], other compounds are able to fulfill the role. For instance, [[chlorine trifluoride]] is able to ignite [[sand]].<ref>{{cite news|last=Lowe|first=Derek|date=February 26, 2008|title=Sand Won't Save You This Time|url=https://www.science.org/content/blog-post/sand-won-t-save-you-time|work=Science|access-date=November 5, 2022|archive-date=February 19, 2023|archive-url=https://web.archive.org/web/20230219062224/https://www.science.org/content/blog-post/sand-won-t-save-you-time|url-status=live}}</ref> Fires start when a [[flammable]] or a combustible material, in combination with a sufficient quantity of an [[oxidizer]] such as oxygen gas or another oxygen-rich compound (though non-oxygen oxidizers exist, such as chlorine),<ref name=Stauffer_NicDaéid_2017/> is exposed to a source of heat or ambient [[temperature]] above the [[flash point]] for the [[fuel]]/oxidizer mix, and is able to sustain a rate of rapid oxidation that produces a [[chain reaction]]. This is commonly called the [[Fire triangle|fire tetrahedron]].<ref>{{cite journal | title=New Techniques and a New Approach to the Effective Extinguishing of Fully Developed Fires in Enclosed Spaces | first1=Norbert | last1=Tuśnio | first2=Paweł | last2=Wolny | journal=Internal Security | volume=8 | issue=1 | year=2016 | doi=10.5604/20805268.1231596 }}</ref> Fire cannot exist without all of these elements in place and in the right proportions. For example, a flammable liquid will start burning only if the fuel and oxygen are in the right proportions.<ref name=Stauffer_NicDaéid_2017>{{cite book | contribution=Chemistry of Fire | first1=E. | last1=Stauffer | last2=NicDaéid | first2=N. | year=2017 | title=Forensic Engineering | pages=137–143 | editor-first=Max M. | editor-last=Houck | series=Advanced Forensic Science Series | publisher=Elsevier, Inc. | isbn=978-0-12-802718-9 | chapter-url=https://books.google.com/books?id=EIPDDgAAQBAJ&pg=PA137 }}</ref> Some fuel-oxygen mixes may require a [[catalyst]], a substance that is not consumed, when added, in any [[chemical]] reaction during combustion, but which enables the reactants to combust more readily.<ref>{{cite journal | title=Catalytic combustion (review) | first=D. L. | last=Trimm | journal=Applied Catalysis | volume=7 | issue=3 | date=September 15, 1983 | pages=249–282 | doi=10.1016/0166-9834(83)80027-X }}</ref> Once ignited, a chain reaction must take place whereby fires can sustain their own heat by the further release of heat energy in the process of combustion and may propagate, provided there is a continuous supply of an oxidizer and fuel.<ref>{{cite journal | title=Fundamentals of Fire Behavior | first=H. T. | last=Gisborne | journal=Fire Management Today | pages=15–23 | volume=64 | issue=1 | date=Winter 2004 | publisher=U.S. Department of Agriculture, Forest Service | url=https://books.google.com/books?id=IhxqmIV7ybUC&pg=PP15 }}</ref> If the oxidizer is oxygen from the surrounding air, the presence of a force of [[gravity]],<ref>{{cite journal | title=An investigation into the effects of gravity level on rate of heat release and time to ignition | first=D. | last=Bryant | journal=Fire and Materials | volume=19 | issue=3 | date=May 1995 | pages=119–126 | doi=10.1002/fam.810190304 }}</ref> or of some similar force caused by acceleration, is necessary to produce [[convection]], which removes combustion products and brings a supply of oxygen to the fire. Without gravity, a fire rapidly surrounds itself with its own combustion products and non-oxidizing gases from the air, which exclude oxygen and [[wikt:extinguish|extinguish]] the fire. Because of this, the risk of fire in a [[spacecraft]] is small when it is [[Orbital maneuver|coasting]] in inertial flight.<ref>{{cite web|url=https://www.youtube.com/watch?v=fuFftT6ZR4k| archive-url=https://ghostarchive.org/varchive/youtube/20211211/fuFftT6ZR4k| archive-date=2021-12-11 | url-status=live|title=Ask Astronaut Greg Chamitoff: Light a Match!|last=NASA Johnson|date=29 August 2008|access-date=30 December 2016|via=YouTube}}{{cbignore}}</ref><ref>{{cite web|url=http://io9.com/5779127/how-does-fire-behave-in-zero-gravity|title=How does fire behave in zero gravity?|first=Esther|last=Inglis-Arkell|work=io9 |date=8 March 2011 |access-date=30 December 2016|archive-date=13 November 2015|archive-url=https://web.archive.org/web/20151113161252/http://io9.com/5779127/how-does-fire-behave-in-zero-gravity|url-status=live}}</ref> This does not apply if oxygen is supplied to the fire by some process other than thermal convection. [[File:Fire tetrahedron.svg|thumb|The fire [[tetrahedron]]]] Fire can be [[fire protection|extinguished]] by removing any one of the elements of the fire tetrahedron.<ref name=Stauffer_NicDaéid_2017/> Consider a natural gas flame, such as from a stove-top burner. The fire can be extinguished by any of the following: * turning off the gas supply, which removes the fuel source; * covering the flame completely, which smothers the flame as the combustion both uses the available oxidizer (the oxygen in the air) and displaces it from the area around the flame with CO<sub>2</sub>; * [[Fire extinguisher#Halons, Halon-replacement clean agents and carbon dioxide|application of an inert gas]] such as [[carbon dioxide]], smothering the flame by displacing the available oxidizer;<ref>{{cite journal | title=Comparative study of single inert gas in confined space inhibiting open flame coal combustion | first1=Baiwei | last1=Lei | first2=Binbin | last2=He | first3=Bowen | last3=Xiao | first4=Peiying | last4=Du | first5=Bing | last5=Wu | journal=Fuel | volume=265 | date=April 1, 2020 | doi=10.1016/j.fuel.2019.116976 }}</ref> * application of water, which removes heat from the fire faster than the fire can produce it<ref>{{cite journal | title=Fire suppression by water sprays | first1=G. | last1=Grant | first2=J. | last2=Brenton | first3=D. | last3=Drysdale | journal=Progress in Energy and Combustion Science | volume=26 | issue=2 | date=April 2000 | pages=79–130 | doi=10.1016/S0360-1285(99)00012-X }}</ref> (similarly, blowing hard on a flame will displace the heat of the currently burning gas from its fuel source, to the same end); or * application of a retardant chemical such as [[halomethane#Fire extinguishing|Halon]] ([[Fire extinguisher#Halons, Halon-replacement clean agents and carbon dioxide|largely banned]] in some countries {{asof|2023|lc=y}}) to the flame, which retards the chemical reaction itself until the rate of combustion is too slow to maintain the chain reaction.<ref>{{cite journal | title=Thermal characteristics of fire extinguishing agents in compartment fire suppression | first1=Tae-Sun | last1=Kim | first2=Tae-Hee | last2=Park | first3=Jeong-Hwa | last3=Park | first4=Ji-Hyun | last4=Yang | first5=Dong-Hun | last5=Han | first6=Byeong-Chae | last6=Lee | first7=Jin-Suk | last7=Kwon | journal=Science Progress | date=August 2024 | volume=107 | issue=3 | doi=10.1177/003685042412634 | pmid=39096047 }}</ref> In contrast, fire is intensified by increasing the overall rate of combustion. Methods to do this include balancing the input of fuel and oxidizer to [[stoichiometry|stoichiometric]] proportions,<ref name=Stauffer_NicDaéid_2017/> increasing fuel and oxidizer input in this balanced mix, increasing the ambient temperature so the fire's own heat is better able to sustain combustion, or providing a catalyst, a non-reactant medium in which the fuel and oxidizer can more readily react. === Flame === {{Main|Flame}} {{See also|Flame test}} [[File:Candle-light-animated.gif|thumb|upright|left|A [[candle]]'s [[flame]]]] A [[diffusion flame]] is a mixture of reacting gases and solids emitting visible, [[infrared]], and sometimes [[ultraviolet]] light, the [[frequency spectrum]] of which depends on the [[chemical composition]] of the burning material and intermediate reaction products. During the burning of [[hydrocarbon]]s, for example wood, or the incomplete [[combustion]] of gas, [[incandescent]] solid particles called [[soot]] produce the familiar red-orange glow of "fire".<ref>{{cite book | title=Principles of Combustion | first1=Allan T. | last1=Kirkpatrick | first2=Kenneth K. | last2=Kuo | year=2024 | page=369 | isbn=9781394187072 | publisher=Wiley | url=https://www.google.com/books/edition/Principles_of_Combustion/uokoEQAAQBAJ?gbpv=1&pg=PA369 }}</ref><ref>{{cite book | title=Fundamentals of Combustion | first=D. P. | last=Mishra | year=2007 | pages=172–174 | isbn=9788120333482 | publisher=PHI Learning | url=https://www.google.com/books/edition/FUNDAMENTALS_OF_COMBUSTION/PwDVwvFBqA0C?gbpv=1&pg=PA172 }}</ref> This light has a [[continuous spectrum]]. Complete combustion of gas has a dim blue color<ref>{{cite web | title=Why does natural gas burn blue? | date=October 31, 2023 | website=Met | url=https://group.met.com/en/media/energy-insight/why-does-natural-gas-burn-blue | access-date=2025-03-03 }}</ref> due to the emission of single-wavelength radiation from various electron transitions in the excited molecules formed in the flame. Usually oxygen is involved, but [[hydrogen]] burning in [[chlorine]] also produces a flame, producing [[hydrogen chloride]] (HCl).<ref>{{cite journal | title=The Atomic Weight of Chlorine: An Attempt to Determine the Equivalent of Chlorine by Direct Burning with Hydrogen | last1=Dixon | first1=Harold B. | last2=Edgar | first2=E. C. | journal=Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character | volume=205 | pages=169–200 | year=1906 | doi=10.1098/rsta.1906.0005 | bibcode=1906RSPTA.205..169D }}</ref> Other possible combinations producing flames, amongst many, are [[fluorine]] with [[hydrogen]],<ref>{{cite journal | title=The Premixed Hydrogen-Fluorine Flame and its Burning Velocity | last1=Grosse | first1=A. V. | last2=Kirshenbaum | first2=A. D. | journal=Journal of the American Chemical Society | volume=77 | issue=19 | pages=5012–5013 | date=October 1955 | doi=10.1021/ja01624a018 | bibcode=1955JAChS..77.5012G }}</ref> and [[hydrazine]] with [[dinitrogen tetroxide]].<ref>{{cite conference | last1=Melof | first1=Brian M. | last2=Grubelich | first2=Mark C. | date=November 15, 2000 | title=Investigation of Hypergolic Fuels with Hydrogen Peroxide | url=https://www.osti.gov/biblio/767866 | language=English | conference=3rd International Hydrogen Peroxide Propulsion Conference | osti=767866 }}</ref> Hydrogen and hydrazine/[[UDMH]] flames are similarly pale blue, while burning [[boron]] and its compounds, evaluated in mid-20th century as a [[Zip fuel|high energy fuel]] for [[Jet engine|jet]] and [[rocket engine]]s, emits intense green flame, leading to its informal nickname of "Green Dragon".<ref>{{cite web | title=Diborane: The Story of an Undergraduate vs a Nobel Laureate | first1=Ollie | last1=Whitley | first2=Stephen | last2=Belding | series=Molecule of the Month | date=October 2020 | publisher=University of Bristol School of Chemistry | url=https://www.chm.bris.ac.uk/motm/diborane/diboraneh.htm | access-date=2025-03-03 }}</ref> [[File:Northwest Crown Fire Experiment.png|thumb|A [[controlled burn]] in the [[Northwest Territories]], showing variations in the flame color due to temperature. The hottest parts near the ground appear yellowish-white, while the cooler upper parts appear red.]] The glow of a flame is complex. [[Black-body radiation]] is emitted from soot, gas, and fuel particles, though the soot particles are too small to behave like perfect blackbodies. There is also [[photon]] emission by de-excited [[atom]]s and [[molecule]]s in the gases. Much of the radiation is emitted in the visible and infrared bands. The color depends on temperature for the black-body radiation, and on chemical makeup for the [[emission spectra]].<ref>{{cite web | title=Examples of blackbody radiators | date=November 12, 1998 | publisher=NASA – Atmospheric Chemistry and Dynamics Laboratory | url=https://acd-ext.gsfc.nasa.gov/anonftp/acd/daac_ozone/Lecture4/Text/Lecture_4/blkbdyexamples.html#candle | access-date=2025-03-05 }}</ref> [[File:Space Fire.jpg|thumb|Fire is affected by gravity. Left: Flame on Earth; Right: Flame on the [[International Space Station|ISS]]]] The common distribution of a flame under normal gravity conditions depends on [[convection]], as soot tends to rise to the top of a general flame, as in a [[candle]] in normal gravity conditions, making it yellow. In [[Weightlessness|microgravity or zero gravity]],<ref>{{cite web | url=https://science.nasa.gov/headlines/y2000/ast12may_1.htm | title=Spiral flames in microgravity] | archive-url=https://web.archive.org/web/20100319113411/http://science.nasa.gov/headlines/y2000/ast12may_1.htm | archive-date=2010-03-19 | publisher=[[National Aeronautics and Space Administration]] | year=2000 }}</ref> such as an environment in [[outer space]], convection no longer occurs, and the flame becomes spherical, with a tendency to become more blue and more efficient (although it may go out if not moved steadily, as the CO<sub>2</sub> from combustion does not disperse as readily in microgravity, and tends to smother the flame). There are several possible explanations for this difference, of which the most likely is that the temperature is sufficiently evenly distributed that soot is not formed and complete combustion occurs.<ref>{{cite web | url=http://microgravity.grc.nasa.gov/combustion/cfm/usml-1_results.htm | title=CFM-1 experiment results | archive-url=https://web.archive.org/web/20070912095009/http://microgravity.grc.nasa.gov/combustion/cfm/usml-1_results.htm |archive-date=2007-09-12 | publisher=National Aeronautics and Space Administration | date=April 2005 }}</ref> Experiments by [[National Aeronautics and Space Administration|NASA]] reveal that [[diffusion flame]]s in microgravity allow more soot to be completely oxidized after they are produced than diffusion flames on Earth, because of a series of mechanisms that behave differently in micro gravity when compared to normal gravity conditions.<ref>{{cite web | url=http://microgravity.grc.nasa.gov/combustion/lsp/lsp1_results.htm | title=LSP-1 experiment results | archive-url=https://web.archive.org/web/20070312020123/http://microgravity.grc.nasa.gov/combustion/lsp/lsp1_results.htm | archive-date=2007-03-12 | publisher=National Aeronautics and Space Administration | date=April 2005 }}</ref> These discoveries have potential applications in [[applied science]] and [[Private industry|industry]], especially concerning [[fuel efficiency]]. ==== Typical adiabatic temperatures ==== {{Main|Adiabatic flame temperature}} The adiabatic flame temperature of a given fuel and oxidizer pair is that at which the gases achieve stable combustion. * [[Oxygen|Oxy]]–[[dicyanoacetylene]] {{convert|4990|C|F|sigfig=2}}<ref name=ScienceNotes>{{cite web | title=Adiabatic Flame Temperature Chart | website=Science Notes | date=January 6, 2021 | first=Anne | last=Helmenstine | url=https://sciencenotes.org/adiabatic-flame-temperature-chart/ | access-date=2025-03-05 }}</ref> * [[Oxygen|Oxy]]–[[acetylene]] {{convert|3997|C|F|sigfig=2}}<ref name=Engineering_Toolbox>{{cite web | title=Adiabatic Flame Temperatures | website=Engineering Toolbox | year=2003 | url=https://www.engineeringtoolbox.com/adiabatic-flame-temperature-d_996.html | access-date=2025-03-01 }}</ref> * [[Oxyhydrogen]] {{convert|3473|C|F|sigfig=2}}<ref name=Engineering_Toolbox/> * [[Air]]–[[acetylene]] {{convert|2500|C|F|sigfig=2}}<ref name=Engineering_Toolbox/> * [[Blowtorch]] (air–[[MAPP gas]]) {{convert|2020|°C|°F|abbr=on|sigfig=2}}<ref name=ScienceNotes/> * [[Bunsen burner]] (air–[[natural gas]]) {{convert|1300|to|1600|C|F|sigfig=2}}<ref>{{Cite web|url=http://www.derose.net/steve/resources/engtables/flametemp.html|title=Flame temperatures|website=www.derose.net|access-date=2007-07-09|archive-date=2014-04-17|archive-url=https://web.archive.org/web/20140417022946/http://www.derose.net/steve/resources/engtables/flametemp.html|url-status=live}}</ref> * [[Candle]] (air–[[paraffin wax|paraffin]]) {{convert|1000|°C|°F|abbr=on|sigfig=2}}<ref name=ScienceNotes/> == Fire science == Fire science is a branch of [[physical science]] which includes fire behavior, dynamics, and [[combustion]]. Applications of fire science include [[fire protection]], [[fire investigation]], and [[wildfire]] management. === Ecology === {{Main|Fire ecology}} Every natural ecosystem on land has its own [[fire regime]], and the organisms in those ecosystems are adapted to or dependent upon that fire regime. Fire creates a mosaic of different [[habitat]] patches, each at a different stage of [[Ecological succession|succession]].<ref>{{cite book | last1=Begon | first1=M. | first2=J. L. | last2=Harper | first3=C. R. | last3=Townsend | year=1996 | title=[[Ecology: From Individuals to Ecosystems]] | edition=Third | publisher=Blackwell Science Ltd. | location=Cambridge, Massachusetts, US | isbn=978-1-4051-1117-1 }}</ref> Different species of plants, animals, and microbes specialize in exploiting a particular stage, and by creating these different types of patches, fire allows a greater number of species to exist within a landscape.<ref>{{Cite journal | last=Hutto | first=Richard L. | date=December 1, 2008 | title=The Ecological Importance of Severe Wildfires: Some Like It Hot | journal=Ecological Applications | language=en | volume=18 | issue=8 | pages=1827–1834 | doi=10.1890/08-0895.1 | pmid=19263880 | issn=1939-5582 | doi-access=free | bibcode=2008EcoAp..18.1827H}}</ref> === Firefighting === {{Main|Firefighting|Aerial firefighting|Wildfire suppression}} [[Fire fighting]] services are provided in most developed areas to extinguish or contain uncontrolled fires. Trained [[firefighter]]s use [[fire apparatus]], water supply resources such as [[water main]]s and [[fire hydrant]]s or they might use A and B class foam depending on what is feeding the fire.<ref>{{cite web | title=Class A and B: What you need to know about foam | first=Geary | last=Roberts | website=Fire Apparatus Magazine | date=April 1, 2010 | url=https://www.fireapparatusmagazine.com/equipment/class-a-and-b-what-you-need-to-know-about-foam/ | access-date=2025-02-28 }}</ref><ref>{{cite web | title=Firefighting tools recommended for fire professionals | first=John | last=Smit | website=World Rescuers | url=https://worldrescuers.com/firefighting-tools/ | access-date=2025-02-28 }}</ref> The early detection of a wildfire outbreak can be performed by a [[fire lookout]] observing from a [[fire lookout tower|tower]] constructed for that purpose. The use of these towers peaked in 1938 and has been in decline since that time; most of the fire surveillance work is now performed using [[infrared sensor]]s and aircraft.<ref>{{cite web | title=History of Fire Tower Lookout and Cabin Rentals | publisher=USDA Forest Service | url=https://www.fs.usda.gov/detail/r1/recreation/?cid=fsp5_030804 | access-date=2025-03-05 }}</ref> [[Aerial firefighting|Fire suppression aircraft]] guided by a lookout can be used to help manage wildfires. These are primarily used in support of ground crews<ref>{{cite web | title=Does Using Airplanes to Put out Forest Fires Actually Work? | first=Ben | last=Christopher | website=Priceonomics | url=https://priceonomics.com/does-using-airplanes-to-put-out-forest-fires/ | access-date=2025-02-28 }}</ref> === {{anchor|Fire management}}Management, prevention and protection systems === {{Main|Wildfire#Prevention|Fire prevention|Fire protection|Fire safety}} [[File:Fire inside an abandoned convent in Massueville, Quebec, Canada.jpg|thumb|An abandoned convent on fire in [[Quebec]]]] Controlling a fire to optimize its size, shape, and intensity is generally called ''fire management'', and the more advanced forms of it, as traditionally (and sometimes still) practiced by skilled cooks, [[blacksmith]]s, [[ironmaster]]s, and others, are highly [[skill]]ed activities. They include knowledge of which fuel to burn; how to arrange the fuel; how to stoke the fire both in early phases and in maintenance phases; how to modulate the heat, flame, and smoke as suited to the desired application; how best to bank a fire to be revived later; how to choose, design, or modify stoves, fireplaces, bakery ovens, or industrial [[Industrial furnace|furnace]]s; and so on. Detailed expositions of fire management are available in various books about blacksmithing, about skilled [[camping]] or [[reconnaissance|military scouting]], and about [[home economics|domestic arts]].<ref>{{cite book | title=Blacksmithing | first=James M. | last=Drew | year=2013 | publisher=Read Books Limited | page=22 | isbn=9781473385436 | url=https://www.google.com/books/edition/Blacksmithing/z_99CgAAQBAJ?gbpv=1&pg=PT22 }}</ref><ref>{{cite book | series=The Safety Network | title=Home Fire Safety Checklist | year=1989 | page=2 | publisher=U.S. Consumer Product Safety Commission | url=https://www.google.com/books/edition/The_Safety_Network/jxJQHY90hm4C?gbpv=1&pg=PP2 }}</ref><ref>{{cite book | title=Leave No Trace in the Outdoors | first=Jeffrey | last=Marion | year=2014 | pages=53–62 | publisher=Stackpole Books | isbn=9780811760515 | url=https://www.google.com/books/edition/Leave_No_Trace_in_the_Outdoors/mbZDBQAAQBAJ?gbpv=1&pg=PA53 }}</ref> Wildfire prevention programs around the world may employ techniques such as ''wildland fire use'' and ''prescribed or [[controlled burn]]s''.<ref>{{cite journal | date=January 1998 | title=UK: The Role of Fire in the Ecology of Heathland in Southern Britain | url=http://www.fire.uni-freiburg.de/iffn/country/gb/gb_1.htm | url-status=live | journal=International Forest Fire News | volume=18 | pages=80–81 | archive-url=https://web.archive.org/web/20110716212702/http://www.fire.uni-freiburg.de/iffn/country/gb/gb_1.htm | archive-date=2011-07-16 | access-date=2011-09-03 }}</ref> ''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.<ref>{{cite web |title=Prescribed Fires |url=http://www.smokeybear.com/prescribed-fires.asp |url-status=dead |archive-url=https://web.archive.org/web/20081020171425/http://www.smokeybear.com/prescribed-fires.asp |archive-date=2008-10-20 |access-date=2008-11-21 |publisher=SmokeyBear.com}}</ref> Fire prevention is intended to reduce sources of ignition. Fire prevention also includes education to teach people how to avoid causing fires.<ref>{{cite web | url=http://www.firecomm.gov.mb.ca/safety_education_nero_and_ashcan.html#6 | title=Fire & Life Safety Education | publisher=[[Manitoba]] Office of the Fire Commissioner | archive-url=https://web.archive.org/web/20081206013312/http://www.firecomm.gov.mb.ca/safety_education_nero_and_ashcan.html#6 | archive-date=December 6, 2008 }}</ref> Buildings, especially schools and tall buildings, often conduct [[fire drill]]s to inform and prepare citizens on how to react to a building fire. Purposely starting destructive fires constitutes [[arson]] and is a crime in most jurisdictions.<ref>{{cite book |last1=Ward |first1=Michael |url=https://books.google.com/books?id=yXt5AW6bJiUC&pg=PA349 |title=Fire Officer: Principles and Practice |date=March 2005 |publisher=Jones & Bartlett Learning |isbn=9780763722470 }}</ref> Model [[building code]]s require [[passive fire protection]] and [[active fire protection]] systems to minimize damage resulting from a fire. A common form of active fire protection is [[fire sprinkler]]s.<ref>{{cite book | title=Principles of Fire Prevention | first=David | last=Diamantes | year=2014 | chapter=Fire Protection Systems Testing | pages=120–132 | ISBN=9781284041866 | publisher=Jones & Bartlett Learning, LLC | chapter-url=https://www.google.com/books/edition/Principles_of_Fire_Prevention/koGHCgAAQBAJ?gbpv=1&pg=PA120 }}</ref> To maximize passive fire protection of buildings, building materials and furnishings in most developed countries are tested for [[Fire-resistance rating|fire-resistance]], combustibility and [[flammability]]. [[Upholstery]], [[carpeting]] and [[plastics]] used in vehicles and vessels are also tested. Where fire prevention and fire protection have failed to prevent damage, [[fire insurance]] can mitigate the financial impact.<ref>{{Cite book |last1=Baars |first1=Hans |url=https://books.google.com/books?id=l6ePCgAAQBAJ&pg=PA33 |title=Foundations of Information Security Based on ISO27001 and ISO27002 |last2=Smulders |first2=Andre |last3=Hintzbergen |first3=Kees |last4=Hintzbergen |first4=Jule |date=2015-04-15 |publisher=Van Haren |isbn=9789401805414 |edition=3rd revised |language=en }}</ref> ==In culture== [[File:Injak bara.jpg|right|thumb|A [[firewalking]] ceremony]] Fire has been an importance element of human culture since the [[Lower Paleolithic]].<ref>{{cite journal | title=The Effects of Fire in Human Life and in the Cuisine from the Paleolithic to the Modern Age | first=Abdullah | last=Badem | journal=Journal of Ecohumanism | year=2024 | volume=3 | issue=6 | pages=269–293 | doi=10.62754/joe.v3i6.4002 }}</ref> Archaeological evidence demonstrates that [[fire worship]] has been widely practiced since [[prehistory]], with dedicated structures found dating from at least the [[Chalcolithic]] period. The religion of [[Zoroastrianism]] is closely linked to this practice. In some societies [[List of fire deities|fire was a deity]], while others viewed it as the [[theophany|manifestation of the divine]].<ref name=Pyne_2016/> The fire in a [[hearth]] was perceived as symbolic of the Heavenly Fire, and thus is considered a sacred component by fire worshipping cultures.<ref>{{cite journal | last=Tashak | first=V. I. | year=2003 | title=Hearths at the Podzvonkaya Palaeolithic site: Evidence suggestive of the spirituality of early populations of the Trans-Baikal region | journal=Archaeology, Ethnology & Anthropology of Eurasia | volume=3 | issue=15 | pages=70–78 }}</ref> The origin of fire became a subject of mythology. In ancient Greek culture, the Titan–god [[Prometheus]] was responsible for [[theft of fire|stealing heavenly fire]] and gifting it to humanity.<ref name=Pyne_2016>{{cite journal | title=Fire in the mind: changing understandings of fire in Western civilization | first=Stephen J. | last=Pyne | journal=Philosophical Transactions of the Royal Society B: Biological Sciences | date=June 5, 2016 | volume=371 | issue=1696 | doi=10.1098/rstb.2015.0166 | pmc=4874404 }}</ref> The use of a [[pyre]] as a [[Funeral|funerary]] practice dates back to at least the Ancient Roman period in the West,<ref>{{cite journal | title=Building a Roman Funeral Pyre | first=David | last=Noy | journal=Antichthon | volume=34 | date=November 2000 | pages=30–45 | doi=10.1017/S0066477400001167 }}</ref> and to about 4,000 years ago on the Indian subcontinent.<ref>{{Cite news |last=Taylor |first=Jerome |date=2008-10-14 |title=The burning issue of Hindu funeral pyres |url=https://www.independent.co.uk/news/uk/home-news/the-burning-issue-of-hindu-funeral-pyres-960259.html |url-status=live |archive-url=https://web.archive.org/web/20250422222730/https://www.independent.co.uk/news/uk/home-news/the-burning-issue-of-hindu-funeral-pyres-960259.html |archive-date=2025-04-22 |access-date=2025-04-22 |work=[[The Independent]]}}</ref> [[Cremation]] of corpses is a tradition long practiced in some cultures, including Hindu. After early religious resistance in some countries, in the 19th century this practice became more widespread and is now commonplace.<ref>{{cite journal | title=Living with the Dead: Burial, Cremation and Memory | first=Ken | last=Warpole | journal=Studies: An Irish Quarterly Review | volume=98 | issue=392 | pages=447–456 | year=2009 | jstor=25660708 }}</ref> In some nations, suicide by [[self-immolation]] remains common.<ref>{{cite journal | title=Why self-immolation? A qualitative exploration of the motives for attempting suicide by self-immolation | first1=Leeba | last1=Rezaie | first2=Seyed Ali | last2=Hosseini | first3=Mehdi | last3=Rassafiani | first4=Farid | last4=Najafi | first5=Jalal | last5=Shakeri | first6=Hamid Reza | last6=Khankeh | journal=Burns | volume=40 | issue=2 | date=March 2014 | pages=319–327 | doi=10.1016/j.burns.2013.06.016 }}</ref> The symbology of fire remains important to the present day. Where wood is plentiful, the [[bonfire]] can be used for celebration purposes, in many cases as part of a tradition. An example is [[Guy Fawkes Night]] in England.<ref>{{cite journal | title=Observing UK Bonfire Night pollution from space: analysis of atmospheric aerosol | first1=R. J. | last1=Pope | first2=A. M. | last2=Marshall | first3=B. O. | last3=O'Kane | journal=Weather | volume=71 | issue=11 | date=November 2016 | pages=288–291 | doi=10.1002/wea.2914 }}</ref> The [[barbecue]] is a fire-based cultural tradition in the United States.<ref>{{cite journal | title=Barbecue as a Historical Looking Glass | first=Zach | last=Myers | journal=Legacy | volume=18 | issue=1 | url=https://opensiuc.lib.siu.edu/legacy/vol18/iss1/7 | access-date=2025-03-06 }}</ref> The fiery ignition of [[fireworks]] has become a modern tradition to celebrate the [[New Year]]s arrival.<ref>{{cite journal | title=Impact of New Year's Eve fireworks on the size resolved element distributions in airborne particles | first1=Stefan | last1=Tanda | first2=Roman | last2=Ličbinský | first3=Jitka | last3=Hegrová | first4=Walter | last4=Goessler | journal=Environment International | pages=371–378 | date=July 2019 | pmid=31078006 | doi=10.1016/j.envint.2019.04.071 | doi-access=free }}</ref> In contrast, [[book burning]] has been used as a form of protest, whether for political, religious, or moral reasons.<ref>{{cite journal | title=Moral Bonfires: An Exploration of Book Burning in American Society | first=Lisa | last=Olson | journal=Dalhousie Journal of Interdisciplinary Management | volume=16 | year=2021 | doi=10.5931/djim.v16i1.10886 | doi-access=free }}</ref> The act of "burning in [[effigy]]" has a similar role, as in the annual [[burning of Judas]] ritual.<ref>{{cite news | title=Greek towns ritually burn Judas as Orthodox celebrate Easter | first1=Petros | last1=Giannakouris | first2=Demetris | last2=Nellas | work=Times of Israel | date=April 9, 2018 | url=https://www.timesofisrael.com/greek-towns-ritually-burn-judas-as-orthodox-celebrate-easter/ | access-date=2025-03-06 }}</ref> Humans lack an instinctual fascination with fire, yet in modern societies adults can become drawn to it out of curiosity. In societies that are dependent on daily fire use, children lose interest in fire at about age seven due to regular exposure.<ref>{{cite web | title=Why We Are Drawn to Fire | first=Natalie | last=Wolchover | date=April 23, 2012 | website=Live Science | url=https://www.livescience.com/19853-fire-fascination.html | access-date=2025-03-11 }}</ref> [[Arson]] is the act of intentionally setting fire to a property. A separate but related behavior is [[pyromania]], which is classified as an [[impulse-control disorder]] where individuals repeatedly fail to resist impulses to deliberately start fires.<ref>{{cite book | title=The American Psychiatric Publishing Textbook of Psychiatry | first=Robert E. | last=Hales | section=Impulse Disorders Not Elsewhere Classified | editor1-first=Stuart C. | editor1-last=Yudofsky | editor2-first=Glen O. | editor2-last=Gabbard | publisher=American Psychiatric Publishing | page=793 | year=2008 | isbn=9781585622573 | url=https://books.google.com/books?id=2RzFWRIAsPAC&pg=PA793 }}</ref> In contrast is [[pyrophobia]], an irrational fear of fire. This [[anxiety disorder]] is a less common phobia.<ref>{{cite web | title=DSM-5 Phobia Types, Diagnosis, and Treatment | date=January 12, 2022 | first=Elizabeth | last=Millard | website=MedCentral | publisher=[[HealthCentral]] | url=https://www.medcentral.com/behavioral-mental/anxiety/assessment-diagnosis-adherence-phobia | access-date=2025-03-11 }}</ref> == See also == {{div col|colwidth=22em}} * ''[[The Chemical History of a Candle]]'' * [[Colored fire]] * [[Deflagration]] * [[Fire making]] * [[Fire pit]] * [[Fire whirl]] * [[Flame test]] * [[Life Safety Code]] * [[List of fire deities]] * [[List of fires]] * [[List of light sources]] * [[Piano burning]] * [[Pyrokinesis]] * [[Pyrolysis]] * [[Pyromania]] * [[Pyrophobia]] {{div col end}} == References == === Notes === {{notelist}} === Citations === {{Reflist}} ==Further reading== * Haung, Kai (2009). [http://ecommons.txstate.edu/arp/287/ Population and Building Factors That Impact Residential Fire Rates in Large U.S. Cities. Applied Research Project] {{Webarchive|url=https://web.archive.org/web/20120308201531/http://ecommons.txstate.edu/arp/287/ |date=2012-03-08 }}. Texas State University. * {{Cite book|title=Community Involvement in and Management of Forest Fires in South East Asia |url=http://www.asiaforests.org/doc/resources/fire/pffsea/Report_Community.pdf |year=2002 |publisher=Project FireFight South East Asia |last=Karki |first=Sameer |access-date=2009-02-13 |url-status=usurped |archive-url=https://web.archive.org/web/20090225154641/http://www.asiaforests.org/doc/resources/fire/pffsea/Report_Community.pdf |archive-date=February 25, 2009 }} * Kosman, Admiel (January 13, 2011). [http://www.haaretz.com/weekend/magazine/sacred-fire-1.329892 "Sacred fire"]. ''[[Haaretz]]''. * Pyne, Stephen J. ''Fire : a brief history'' (University of Washington Press, 2001). ** Pyne, Stephen J. ''World fire : the culture of fire on earth'' (1995) [https://archive.org/details/worldfireculture0000pyne online] ** Pyne, Stephen J. ''Tending fire : coping with America's wildland fires'' (2004) [https://archive.org/details/tendingfirecopin0000pyne_x6q9 online] ** Pyne, Stephen J. ''Awful splendour : a fire history of Canada'' (2007) [https://archive.org/details/awfulsplendourfi0000pyne online] ** Pyne, Stephen J. ''Burning bush : a fire history of Australia'' (1991) [https://archive.org/details/burningbushfireh0000pyne online] ** Pyne, Stephen J. ''Between Two Fires: A Fire History of Contemporary America'' (2015) ** Pyne, Stephen J. ''California: A Fire Survey'' (2016) * Safford, Hugh D., et al. "Fire ecology of the North American Mediterranean-climate zone." in ''Fire ecology and management: Past, present, and future of US forested ecosystems'' (2021): 337–392. re California and its neighbors [https://www.fs.usda.gov/research/treesearch/download/63841.pdf online] == External links == {{Commons}} {{Wikiquote|Fire}} * [http://www.howstuffworks.com/Fire.htm How Fire Works] at [[HowStuffWorks]] * [http://www.straightdope.com/columns/021122.html What exactly is fire?] from [[The Straight Dope]] * [https://www.pbs.org/wgbh/nova/fire/onfire.html On Fire], an [[Adobe Flash]]–based science tutorial from the [[Nova (American TV program)|''NOVA'' (TV series)]] * [http://discovermagazine.com/2011/oct/20-things-you-didnt-know-about-fire "20 Things You Didn't Know About... Fire"] from ''[[Discover (magazine)|Discover]]'' magazine {{Fire}} {{Natural disasters}} {{Authority control}} [[Category:Fire| ]] [[Category:Terrestrial plasmas]] [[Category:Articles containing video clips]] [[Category:Cooking techniques]]
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