A flare, also sometimes called a fusee, is a type of pyrotechnic that produces a brilliant light or intense heat without an explosion. Flares are used for distress signalling, illumination, or defensive countermeasures in civilian and military applications. Flares may be ground pyrotechnics, projectile pyrotechnics, or parachute-suspended to provide maximum illumination time over a large area. Projectile pyrotechnics may be dropped from aircraft, fired from rocket or artillery, or deployed by flare guns or handheld percussive tubes.

US Army 52253 Best Warrior At Night
Illumination flares being used during military training exercises


The earliest recorded use of gunpowder for signalling purposes was the 'signal bomb' used by the Chinese Song Dynasty as the Mongol-led Yuan Dynasty besieged Yangzhou in 1276.[1] These soft-shelled bombs, timed to explode in mid-air, were used to send messages to a detachment of troops far in the distance. Another mention of the signal bomb appears in a text dating from 1293 requesting their collection from those still stored in Zhejiang.[1] A signal gun appears in Korea by 1600. The Wu I Thu Phu Thung Chih or Illustrated Military Encyclopedia written in 1791 depicts a signal gun in an illustration.[2]


Flare 0
Three road flares burning
26.5mm Flare Gun
A conventional flare pistol. This particular model uses 26.5mm flares (manufactured by Patel Ballistics).

Flares produce their light through the combustion of a pyrotechnic composition. The ingredients are varied, but often based on strontium nitrate, potassium nitrate, or potassium perchlorate and mixed with a fuel such as charcoal, sulfur, sawdust, aluminium, magnesium, or a suitable polymeric resin.[3] Flares may be colored by the inclusion of pyrotechnic colorants. Calcium flares are used underwater to illuminate submerged objects.

Movement against perchlorate flares

Many in-service colored signal flares and spectrally balanced decoy flares contain perchlorate oxidizers. Perchlorate, a type of salt in its solid form, dissolves and moves rapidly in groundwater and surface water. Even in low concentrations in drinking water supplies, perchlorate is known to inhibit the uptake of iodine by the thyroid gland. While there are currently no US federal drinking water standards for perchlorate, some states have established public health goals, or action levels, and some are in the process of establishing state maximum contaminant levels. For example, the US Environmental Protection Agency have studied the impacts of perchlorate on the environment as well as drinking water.[4] California has also issued guidance regarding perchlorate use.[5]

US courts have taken action regarding the use of perchlorate in manufacturing pyrotechnic devices such as flares. For example, in 2003, a federal district court in California found that Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) applied because perchlorate is ignitable and therefore a “characteristic” hazardous waste. (see Castaic Lake Water Agency v. Whittaker, 272 F. Supp. 2d 1053, 1059–61 (C.D. Cal. 2003)).

Civilian use

Wien - Anti-Akademikerball-Demo der Offensive gegen rechts - IIIb
Red Flares used at a demonstration in Vienna

In the civilian world, flares are commonly used as signals, and may be ignited on the ground or fired as an aerial signal from a pistol-like flare gun, or launched from a self-contained tube. Flares are commonly found in marine survival kits.

Maritime distress signal

Red flares, either sent as a rocket or held in the hand, are widely recognized as a maritime distress signal.[6] RMS Titanic however used rocket-launched distress shells to attract assistance, emitting white stars to a great height and a deafening sound.

The International Convention for the Safety of Life at Sea (SOLAS) has standards for visual signals, including both handheld and aerial flares. Handheld flares must burn for at least 1 minute at an average luminosity of 15,000 candela, while aerial flares must burn for at least 40 seconds with 30,000 candela average luminosity.[7] Both should burn in a bright red colour. Nations which are members of SOLAS require vessels to carry visual signals on board.


Indiana Harbor Belt Railroad switchman signaling "stop", Calumet City, Illinois, 1943 (LOC fsac.1a34695)
An Indiana Harbor Belt Railroad brakeman uses a fusee to demonstrate a hand signal indicating "stop".

Another type of flare is the fusee, which burns for 10–60 minutes with a bright red light. Fusees are commonly used to indicate obstacles or advise caution on roadways at night; in this usage they are also called highway flares, road flares, or ground flares. They are commonly found in roadside emergency kits.

Fusees are also known as railroad flares and are commonly used to perform hand signals in rail transport applications. Since they can be used only once, fusees nowadays are usually intended for emergency use (as opposed to the lanterns typically used during normal operating conditions). However, in the days before train radio communications, fusees were used to keep trains apart in dark territory. A railroad fusee was timed to burn for ten minutes and quantities were dropped behind a train to ensure a safe spacing. If a following train encountered a burning fusee it was not to pass until the fusee burned out. Fusees made specifically for railroad use can be distinguished from highway fusees by a sharp steel spike at one end, used to embed the fusee upright in a wooden railroad tie.

In forestry and firefighting, fusees are sometimes used in wildland fire suppression and in the ignition of controlled burns. They ignite at 191 °C (376 °F) and burn as hot as 1,600 °C (2,900 °F).[8] They are especially effective in igniting burnouts or backburns in very dry conditions, but not so effective when fuel conditions are moist. Since controlled burns are often done during relatively high humidity levels (on the grounds that they could not be safely contained during periods of very low humidity), the driptorch is more effective and more often used. Fusees are also commonly carried by wildland firefighters for emergency use, to ignite an escape fire in surrounding fuels in case of being overrun by a fire if no other escape routes are available.

Calcium phosphide is often used in naval flares, as in contact with water it liberates phosphine which self ignites in contact with air; it is often used together with calcium carbide which releases acetylene.

Military use

Maritime signal flare

In 1859, Martha Coston patented the Coston flare based on early work by her deceased husband Benjamin Franklin Coston.[9] It was used extensively by the U.S. Navy during the Civil War and by the United States Life-Saving Service to signal to other ships and to shore.


In 1922, a "landing flare" was an aerial candle attached to a parachute and used for landing an airplane in the dark. The flare burned for less than 4 minutes and the candle power was about 40,000 lumens.[10]


A special variety of flares is used in military aircraft as a defensive countermeasure against heat-seeking missiles. These flares are usually discharged individually or in salvos by the pilot or automatically by tail-warning devices, and are accompanied by vigorous evasive maneuvering. Since they are intended to deceive infrared missiles, these flares burn at temperatures of thousands of degrees, incandescing in the visible spectrum as well.


Flares connected to tripwires are used to guard an area against infiltration. The flare begins burning when the tripwire is triggered, providing both alarm and illumination.


Under the UN hazard number system, pyrotechnic flares are designated class 1.4 explosives.[11]

Several U.S. states, including California and Massachusetts, have begun regulating levels of potassium perchlorate, which can be unsafe at certain levels in drinking water. Contaminated drinking water can lead to such symptoms as gastric irritation, nausea, vomiting, fever, skin rashes, and even fatal aplastic anemia.[12]

See also


  1. ^ a b Joseph Needham (1986). Science and Civilisation in China: The Gunpowder Epic. Cambridge University Press. p. 169. ISBN 978-0-521-30358-3.
  2. ^ Needham (1986), p. 331.
  3. ^ "What is in road flares?". Retrieved 16 January 2009.
  4. ^ http://www.epa.gov/safewater/contaminants/unregulated/perchlorate.html
  5. ^ "Archived copy". Archived from the original on 27 June 2010. Retrieved 24 June 2010.CS1 maint: archived copy as title (link)
  6. ^ "The Merchant Shipping (Distress Signals and Prevention of Collisions) Regulations 1996" (PDF). UK Maritime and Coast Guard Agency. 1996. Retrieved 23 July 2013.
  7. ^ "Internation Life-Saving Appliance (LSA) Code".
  8. ^ The New Generation Fire Shelter (PDF). National Wildfire Coordinating Group. March 2003. Retrieved 16 January 2009.
  9. ^ Vare, Ethlie Ann; Ptacek, Greg (2002). Patently female : from AZT to TV dinners : stories of women inventors and their breakthrough ideas. New York: Wiley. p. 23. ISBN 0471023345.
  10. ^ Hugh Chisholm (1922). The Encyclopædia Britannica: Abbe to English history ("The first of the new volumes"). The Encyclopædia Britannica Company. p. 86. Retrieved 13 October 2011. Electric-Ignition Parachute Flare-Bombs...a landing flare to enable pilots to land in the dark...The candles burn for from 2½ to 3½ min....the candle power is about 40,000 lumens.
  11. ^ "History of Flares". SiriusSignal.com. Sirius Signal. Retrieved 8 June 2015.
  12. ^ Borowicz; et al. (18 December 2014). "Disposal of Pyrotechnic Visual Distress Signals" (PDF). Cite journal requires |journal= (help)

Further reading

External links


Bell-bottoms (or flares) are a style of trousers that become wider from the knees downward, forming a bell-like shape of the trouser leg.


A disease is a particular abnormal condition that negatively affects the structure or function of part or all of an organism, and that is not due to any external injury. Diseases are often construed as medical conditions that are associated with specific symptoms and signs. A disease may be caused by external factors such as pathogens or by internal dysfunctions. For example, internal dysfunctions of the immune system can produce a variety of different diseases, including various forms of immunodeficiency, hypersensitivity, allergies and autoimmune disorders.

In humans, disease is often used more broadly to refer to any condition that causes pain, dysfunction, distress, social problems, or death to the person afflicted, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms, deviant behaviors, and atypical variations of structure and function, while in other contexts and for other purposes these may be considered distinguishable categories. Diseases can affect people not only physically, but also mentally, as contracting and living with a disease can alter the affected person's perspective on life.

Death due to disease is called death by natural causes. There are four main types of disease: infectious diseases, deficiency diseases, hereditary diseases (including both genetic diseases and non-genetic hereditary diseases), and physiological diseases. Diseases can also be classified in other ways, such as communicable versus non-communicable diseases. The deadliest diseases in humans are coronary artery disease (blood flow obstruction), followed by cerebrovascular disease and lower respiratory infections. In developed countries, the diseases that cause the most sickness overall are neuropsychiatric conditions, such as depression and anxiety.

The study of disease is called pathology, which includes the study of etiology, or cause.

EQ Virginis

EQ Virginis is a flare star in the constellation of Virgo. It is an orange dwarf of spectral type K5Ve and is a member of a IC 2391 moving group. The moving group of stars is between 30 and 50 million years old.

Flare (countermeasure)

A flare or decoy flare is an aerial infrared countermeasure used by a plane or helicopter to counter an infrared homing ("heat-seeking") surface-to-air missile or air-to-air missile. Flares are commonly composed of a pyrotechnic composition based on magnesium or another hot-burning metal, with burning temperature equal to or hotter than engine exhaust. The aim is to make the infrared-guided missile seek out the heat signature from the flare rather than the aircraft's engines.

Flare (magazine)

Flare is a Canadian online fashion magazine. It is published by Rogers Communications.

Flare Gun

Flare Gun is an album by the Japanese noise musician Merzbow. It was released as an LP in a limited edition of 479 copies.

Flare gun

A flare gun, also known as a Very pistol or signal pistol, is a large-bore handgun that discharges flares. The flare gun is used to create illumination for improved vision or as a distress signal. A flare gun can be used as a deadly weapon; however, that is not its intended function.

Flare star

A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to the magnetic energy stored in the stars' atmospheres. The brightness increase is across the spectrum, from X rays to radio waves. The first known flare stars (V1396 Cygni and AT Microscopii) were discovered in 1924. However, the best-known flare star is UV Ceti, first observed to flare in 1948. Today similar flare stars are classified as UV Ceti type variable stars (using the abbreviation UV) in variable star catalogs such as the General Catalogue of Variable Stars.

Most flare stars are dim red dwarfs, although recent research indicates that less massive brown dwarfs might also be capable of flaring. The more massive RS Canum Venaticorum variables (RS CVn) are also known to flare, but it is understood that these flares are induced by a companion star in a binary system which causes the magnetic field to become tangled. Additionally, nine stars similar to the Sun had also been seen to undergo flare events prior

to the flood of superflare data from the Kepler observatory.

It has been proposed that the mechanism for this is similar to that of the RS CVn variables in that the flares are being induced by a companion, namely an unseen Jupiter-like planet in a close orbit.

Gas flare

A gas flare, alternatively known as a flare stack, is a gas combustion device used in industrial plants such as petroleum refineries, chemical plants, natural gas processing plants as well as at oil or gas production sites having oil wells, gas wells, offshore oil and gas rigs and landfills.

In industrial plants, flare stacks are primarily used for burning off flammable gas released by pressure relief valves during unplanned over-pressuring of plant equipment. During plant or partial plant startups and shutdowns, flare stacks are also often used for the planned combustion of gases over relatively short periods.

Gas flaring at many oil and gas production sites protects against the dangers of over-pressuring industrial plant equipment. An example of the consequences of failure to flare escaping gas was evident in the Bhopal disaster when a flare tower was broken and couldn't flare escaping methyl isocyanate gas (The gas had been in an overpressured tank and released by a safety valve), which resulted in its release into the surrounding area. When petroleum crude oil is extracted and produced from oil wells, raw natural gas associated with the oil is brought to the surface as well. Especially in areas of the world lacking pipelines and other gas transportation infrastructure, vast amounts of such associated gas are commonly flared as waste or unusable gas. The flaring of associated gas may occur at the top of a vertical flare stack (as in the adjacent photo) or it may occur in a ground-level flare in an earthen pit. Preferably, associated gas is reinjected into the reservoir, which saves it for future use while maintaining higher well pressure and crude oil producibility.

Lens flare

Lens flare refers to a phenomenon wherein light is scattered or flared in a lens system, often in response to a bright light, producing a sometimes undesirable artifact within the image. This happens through light scattered by the imaging mechanism itself, for example through internal reflection and scattering from material imperfections in the lens. Lenses with large numbers of elements such as zooms tend to exhibit greater lens flare, as they contain a relatively large number of interfaces at which internal scattering may occur. These mechanisms differ from the focused image generation mechanism, which depends on rays from the refraction of light from the subject itself.

Flare manifests itself in two ways: as visible artifacts, and as a haze across the image. The haze makes the image look "washed out" by reducing contrast and color saturation (adding light to dark image regions, and adding white to saturated regions, reducing their saturation). Visible artifacts, usually in the shape of the lens iris, are formed when light follows a pathway through the lens that contains one or more reflections from the lens surfaces.

Flare is particularly caused by very bright light sources. Most commonly, this occurs when shooting into the sun (when the sun is in frame or the lens is pointed in the direction of the sun), and is reduced by using a lens hood or other shade. For good-quality optical systems, and for most images (which do not have a bright light shining into the lens), flare is a secondary effect that is widely distributed across the image and thus not visible, although it does reduce contrast.

Lens hood

In photography, a lens hood or lens shade is a device used on the front end of a lens to block the Sun or other light source(s) to prevent glare and lens flare. Lens hoods may also be used to protect the lens from scratches and the elements without having to put on a lens cover.

The geometry of a lens hood is dependent on three parameters: the focal length of the lens, the size of the front lens element and the dimensions of the image sensor or film in the camera.

MadCap Software

MadCap Software is an American computer software firm headquartered in San Diego, California that creates help authoring tools and solutions for technical writers and documentations teams. Several principal managers, software engineers, and support personnel were recruited from rival firms, such as Adobe Systems and Macromedia, to found MadCap Software. MadCap's authoring tools are all based on xHTML.

Rosa 'Sun Flare'

Rosa 'Sun Flare', (aka JACjem), is a yellow floribunda rose cultivar, bred by William Warriner and introduced into United States by Jackson & Perkins in 1981. The rose won a gold medal in Japan in 1981, Portland in 1982 and was named an All-America Rose Selections winner in 1983.

Solar flare

A solar flare is a sudden flash of increased brightness on the Sun, usually observed near its surface

and in close proximity to a sunspot group.

Powerful flares are often, but not always, accompanied by a coronal mass ejection. Even the most powerful flares are barely detectable in the total solar irradiance (the "solar constant").Solar flares occur in a power-law spectrum of magnitudes; an energy release of typically 1020 joules of energy suffices to produce a clearly observable event, while a major event can emit up to 1025 joules.Flares are closely associated with the ejection of plasmas and particles through the Sun's corona into outer space; flares also copiously emit radio waves.

If the ejection is in the direction of the Earth, particles associated with this disturbance can penetrate into the upper atmosphere (the ionosphere) and cause bright auroras, and may even disrupt long range radio communication.

It usually takes days for the solar plasma ejecta to reach Earth. Flares also occur on other stars, where the term stellar flare applies.

High-energy particles, which may be relativistic, can arrive almost simultaneously with the electromagnetic radiations.

On July 23, 2012, a massive, potentially damaging, solar storm (solar flare, coronal mass ejection and electromagnetic radiation) barely missed Earth. In 2014, Pete Riley of Predictive Science Inc. published a paper in which he attempted to calculate the odds of a similar solar storm hitting Earth within the next 10 years, by extrapolating records of past solar storms from the 1960s to the present day. He concluded that there may be as much as a 12% chance of such an event occurring.


Spreadtrum Communications, Inc. (Chinese: 展讯通信有限公司; pinyin: Zhǎnxùn Tōngxìn Yǒuxiàn Gōngsī), now Unisoc, is a Chinese fabless semiconductor company headquartered in Shanghai which produces chipsets for mobile phones.

Spreadtrum has research centres in Shanghai, Beijing, Tianjin, Suzhou, Hangzhou, Chengdu, Xiamen, US, Finland and India, technical support centre in Shenzhen, and international field support offices in South Korea, Taiwan and Mexico. Its products support a broad range of wireless communications standards, including GSM, GPRS, EDGE, TD-SCDMA, W-CDMA, HSPA+ and TD-LTE.

The company originally produced chips for GSM handsets, but most of its resources are now focused on the Chinese TD-SCDMA 3G standard. In addition to GSM and combined GSM/TD-SCDMA baseband chipsets, Spreadtrum also supplies chips for two Chinese mobile TV standards: TD-MBMS and CMMB. Spreadtrum's customers accounted for 50% of TD-SCDMA handset sales in China Mobile's current round of TD-SCDMA trials.Spreadtrum was formerly a public company listed on NASDAQ, but agreed to an acquisition by Tsinghua Unigroup in July 2013 for about $1.78 billion; the deal completed on 23 December 2013.In 2014, Tsinghua Unigroup acquired RDA Microelectronics for US$907 Million. RDA Microelectronics was a fabless semiconductor company that designs, develops and markets wireless system-on-chip and radio-frequency semiconductors for cellular, connectivity and broadcast applications.

In 2018, the company was renamed Unisoc. Also in 2018, the company began working on a 5G smartphone platform with an Intel 5G modem. In February 2018, Spreadtrum was introducing high-end smartphones with Augmented Reality.

Tidal disruption event

A tidal disruption event (also known as a tidal disruption flare) is an astronomical phenomenon that occurs when a star approaches sufficiently close to a supermassive black hole that it is pulled apart by the black hole's tidal force, experiencing spaghettification. A portion of the star's mass can be captured into an accretion disk around the black hole, resulting in a temporary flare of electromagnetic radiation as matter in the disk is consumed by the black hole.


Turntablism is the art of manipulating sounds and creating new music, sound effects, mixes and other creative sounds and beats, typically by using two or more turntables and a cross fader-equipped DJ mixer. The mixer is plugged into a PA system for live events and/or broadcasting equipment (if the DJ is performing on radio, TV or Internet radio) so that a wider audience can hear the turntablist's music. Turntablists manipulate records on a turntable by moving the record with their hand to cue the stylus to exact points on a record, and by touching or moving the platter or record to stop, slow down, speed up or, spin the record backwards, or moving the turntable platter back and forth (the popular rhythmic "scratching" effect which is a key part of hip hop music), all while using a DJ mixer's crossfader control and the mixer's gain and equalization controls to adjust the sound and level of each turntable. Turntablists typically use two or more turntables and headphones to cue up desired start points on different records.

Turntablists, who are often called DJs (or "deejays"), generally prefer direct-drive turntables over belt-driven or other types, because the belt can be stretched or damaged by "scratching" and other turntable manipulation such as slowing down a record, whereas a direct drive turntable can be stopped, slowed down, or spun backwards without damaging the electric motor. The word turntablist was originated by Luis "DJ Disk" Quintanilla (Primus, Herbie Hancock, Invisibl Skratch Piklz). After a phone conversation with Disk, it was later popularised in 1995 by DJ Babu to describe the difference between a DJ who simply plays and mixes records and one who performs by physically manipulating the records, stylus, turntables, turntable speed controls and mixer to produce new sounds. The new term coincided with the resurgence of hip-hop DJing in the 1990s.

John Oswald described the art: "A phonograph in the hands of a 'hiphop/scratch' artist who plays a record like an electronic washboard with a phonographic needle as a plectrum, produces sounds which are unique and not reproduced—the record player becomes a musical instrument." Some turntablists use turntable techniques like beat mixing/matching, scratching, and beat juggling. Some turntablists seek to have themselves recognized as traditional musicians capable of interacting and improvising with other performers. Depending on the records and tracks selected by the DJ and his/her turntablist style (e.g., hip hop music), a turntablist can create rhythmic accompaniment, percussion breaks, basslines or beat loops, atmospheric "pads", "stabs" of sudden chords or interwoven melodic lines.


A wrench or spanner is a tool used to provide grip and mechanical advantage in applying torque to turn objects—usually rotary fasteners, such as nuts and bolts—or keep them from turning.

In Commonwealth English (excluding Canada), spanner is the standard term. The most common shapes are called open-ended spanner and ring spanner. The term wrench is generally used for tools that turn non-fastening devices (e.g. tap wrench and pipe wrench), or may be used for a monkey wrench - an adjustable pipe wrench.In North American English, wrench is the standard term. The most common shapes are called open-end wrench and box-end wrench. In American English, spanner refers to a specialised wrench with a series of pins or tabs around the circumference. (These pins or tabs fit into the holes or notches cut into the object to be turned.) In American commerce, such a wrench may be called a spanner wrench to distinguish it from the British sense of spanner.

Higher quality wrenches are typically made from chromium-vanadium alloy tool steels and are often drop-forged. They are frequently chrome-plated to resist corrosion and for ease of cleaning.

Hinged tools, such as pliers or tongs, are not generally considered wrenches in English, but exceptions are the plumber wrench (pipe wrench in British English) and Mole wrench (sometimes Mole grips in British English).

The word can also be used in slang to describe an unexpected obstacle, for example, "He threw a spanner in the works" (in U.S. English, "monkey wrench").

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