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Red

Red

Red is a color at the lowest frequencies of light discernible by the human eye. Red light has a wavelength range of roughly 630-760 nm. Lower frequencies are called infrared, or far red. Red is an additive primary color, complementary to cyan. It was once considered to be a subtractive primary color, and is still sometimes described as such in non-scientific literature; however, the colors cyan, magenta and yellow are now known to be closer to the true subtractive primary colors detected by the eye, and are used in modern color printing.

Usage, symbolism, colloquial expressions


- Red catches people's attention, and is often used to indicate danger or emergency.
  - Red is the color of heat and fire. Taps for hot water are often labeled red. Red is commonly the color of fire alarm boxes, fire extinguishers, and the firefighter profession itself.
  - Red denotes "stop" in, for instance, stop signs, traffic signals, brake lights, or the flashing lights of a school bus.
  - A Red Cross, Red Crescent or Red Crystal flag signify medical personnel, facilities, or equipment, or the Geneva conventions.
  - Red indicates extreme danger on Western color-coded scales, such as wildfire hazard signs or the U.S. Homeland Security Advisory System.
  - In auto racing, a red flag signals all cars to immediately stop. The redline is the maximum speed an engine and its components can run.
  - Emergency exits on passenger aircraft are indicated by red signs and lighting.
  - "Redlining" is delineating a forbidden area (as on a map), for instance where a company denies or increases the cost of services, and is illegal in various circumstances in the U.S.
  - With ships on collision courses, the ship on starboard tack sees the Green for Go light on the ship on port tack, while the ship on port tack sees the Red for Stop light on the ship on starboard tack.
- In religion, red represents the color of fire and so symbolizes the presence of God. It is the liturgical color for Pentecost. It is also considered the color of the Church, since red can also symbolize the blood of martyrs. It is sometimes used for Holy Thursday and during Eastertide. In Catholic tradition it is used for Palm Sunday in anticipation of the death of Jesus.
- In the original Star Trek series, red uniforms are for engineering and security personnel. (On away missions, ensigns in red uniform would often get killed - see Redshirt (science fiction)). For Star Trek: The Next Generation onwards, red uniforms are for command personnel.
- In the Power Rangers and Super Sentai series, the Red Ranger is usually the leader of the team.
- The red M&Ms spokescandy has a cynical personality.
- In the Star Wars universe, red is traditionally (although not always in the Expanded Universe) the color of light saber used by the Sith, evil users of the Force. This is because a red light saber crystal is synthetically made, and therefore separated from the natural world. A red crystal is supposed to be stronger.
- In Association football (soccer), the referee shows a red card to a player who is being sent-off.
- Red can sometimes symbolize evil in any kind of work that involves a villain.
- Being the color of blood, red was associated with the Roman mythology god of war, Mars, and the reddish planet Mars became named after him. The phrase "red-blooded" describes someone who is audacious, robust, or virile; it is sometimes used to contrast with a cold or effete "blue blood" although the terms are unrelated in origin.
- Red is the color of sex and romance, (because of its association with blood, which is responsible for arousal) thus the red of a Valentine heart and of a "red-light district". But it may also denote anger, as in the expression seeing red, or embarrassment, as in being red-faced.
- In English heraldry, red denoted ardent affection or love, while crimson (blood-color) stood for boldness, enthusiasm, or impetuosity. (The American Girls Handy Book, p. 369-370)
- Before the French revolution red was the color of the flag signifying the imposition of martial law.
- Beginning with the Revolution of 1848, "Socialist" red was used as a color of European Revolutionaries, often in the form of the red flag. It was also used by Garibaldi's camicie rosse ("redshirts") in the Italian Risorgimento, and taken up by Leftist and generally radical groups, while the white of legitimist Bourbon partisans became associated with pre-World War I conservatives. This relates to the term "Blood of the workers", representing the suffering of the proletariat.
  - For instance the Civil War in Russia and the Civil War in Finland were fought between the "Red Army" and various "White Armies".
  - The identification of Communism with "Socialist" red (with the red flag being the primary color of the flag of the Soviet Union) and the red star being a Communist emblem led to such Cold War phrases as "the Red Menace" and "Red China" (distinguished from Nationalist China, "Free China," or Taiwan). The color was also associated with political vehicles such as the Red Guard in China and the Red Guards during the Russian Revolution of 1917 as well as with left wing paramilitary groups such as the Red Army Faction in Germany and the Japanese Red Army.
  - Red remains associated with parties on the left of the political spectrum, with several notable exceptions (see "Political Parties" below) Japanese Red Army
- In Chinese symbolism, red is the color of good luck and is used for decoration and wedding attire. Money in Chinese societies is traditionally given in red packets. See also The East is Red. Mao Zedong was sometimes referred to as a "red sun".
- Red ink is also used to denote debt - as well as losses on a balance sheet (hence the phrase, "in the red" usually indicates economic losses).
- In North American stock markets, red is used to denote a drop in stock prices. In East Asian stock markets, red is used to denote a rise in stock prices.
- In maps of political parties, red is traditionally used for the following parties:
  - Australia: Labor
  - Canada: Liberal Party of Canada
  - Germany: Sozialdemokratische Partei Deutschlands (Social Democratic party of Germany) and Partei des Demokratischen Sozialismus (Party of Democratic Socialism)
  - The Netherlands: Partij van de Arbeid (Socialist party)
  - United Kingdom: Labour Party
  - United States: Republican Party, since the 2000 presidential election, when contrasted with blue representing Democrats.
- Red is one of the Christmas colors, with green, white, or both.
- Red, along with yellow and orange, is thought to provoke hunger, hence its use in logos by food vendors.
- In the history of Japan red is the color of military flags used by the Heike (or Taira) clan and of the Genji (or Minamoto) clan, two clans that struggled for power at the close of the Heian era, in the late 12th century.
- Red is the last film in the Three Colors trilogy by Krzysztof Kieślowski.
- Red is the color claimed by the street gangs Bloods and Norteños.
- Red is the word for a fish of the genus Myripristis in Tobian.
- Red is an album by progressive rock band King Crimson.
- Red is the color of the lowest-value balls in snooker. There are 15 at the beginning of a game, each worth 1 point.
- Red Indians is a British term for Native Americans.
- Red and black are colors associated with Satanism (the life force, excitement, arousal etc, which are sustained by ruthless self interest and materialism, or, "darkness") and were also the colors of the Nazi party, and are sometimes claimed by neo-Nazis or sympathizers.
- Red is the color commonly associated with the British Army (i.e Redcoats) and is also used to describe someone of British nationality.
- Red is the color often used for the Roman, British and Soviet Empires.
- Red is the color used for critical or important systems (such as emergency lighting) that operate in low-light or night-time conditions, as rod cells in the human eye do not respond to it and therefore does not interfere in the eye's ability to focus in dim environments.
- A red filter used in black and white photography increases contrast in most scenes. For example, combined with a polarizer, it can turn the sky black. Films simulating the effects of infrared film (such as Ilford's SFX 200) do so by being much more sensitive to red than to other colors.
- Oxygenated blood is red due to the presence of hemoglobin. Red light is the first to be absorbed by sea water, so that many fish and marine invertebrates that appear bright red are black in their native habitat.

Variations


- Scarlet - a shade of red that tends towards red-orange and has no hint of blue
- Vermilion - a fiery shade of red that tends toward red-orange to a silghtly greater degree than scarlet, prepared from cinnabar, the artificial red sulphide of mercury used as a pigment
- Pink - a very light, unsaturated red, traditionally the color of pinks
- Maroon - a deep, dark, brownish (desaturated) red
- Venetian Red (also known as India Red or Indian Red) - A shade of brownish red prepared from sulphate of iron.
- Carmine - a dark, blue-tinged red traditionally the color of a dye made from the cochineal insect
- Rose is a range of colors on the blue side of red
  - Damask specifically refers to the color of the Damask rose.
- Crimson - a shade of red that has no hint of yellow and leans towards red-violet
- Cardinal - a vivid red
- Cerise - another dark blue-red
- Peach is a range of colors on the yellow side of red and generally tending toward a light tint.
- Burgundy - another dark, sometimes grayish violet-red

Red pigments


- Alizarin
- Carmine
- Indian red
- Red lead
- Red ochre
- Vermilion

See also


- List of colors
- Category:Optical spectrum ja:赤 simple:Red th:สีแดง

Color

Color or colour is the perception of the frequency (or wavelength) of light, and can be compared to how pitch (or a musical note) is the perception of the frequency or wavelength of sound. It is a perception which in humans derives from the ability of the fine structures of the eye to distinguish (usually three) differently filtered analyses of a view. The perception of color is influenced by biology (some people are born seeing colors differently or not at all; see color blindness), long-term history of the observer, and also by short-term effects such as the colors nearby. (This is the basis of many optical illusions.) The science of color is sometimes called chromatics. It includes the perception of color by the human eye, the origin of color in materials, color theory in art, and the physics of color in the electromagnetic spectrum.

Physics of color

The colors of the visible light spectrum.
color wavelength interval frequency interval
red ~ 625-740 nm ~ 480-405 THz
orange ~ 590-625 nm ~ 510-480 THz
yellow ~ 565-590 nm ~ 530-510 THz
green ~ 500-565 nm ~ 600-530 THz
cyan ~ 485-500 nm ~ 620-600 THz
blue ~ 440-485 nm ~ 680-620 THz
violet ~ 380-440 nm ~ 790-680 THz
Continuous optical spectrum
Image:Spectrum441pxWithnm.png
Designed for monitors with gamma 1.5.
Computer "spectrum"
Image:Computerspectrum.png
The bars below show the relative intensities of the three
colors mixed to make the color immediately above.
Color, frequency, and energy of light.
Color \lambda \,\!/nm \nu \,\!/1014 Hz \nu_b \,\!/104 cm-1 E \,\!/eV E \,\!/kJ mol-1
Infrared >1000 <3.00 <1.00 <1.24 <120
Red 700 4.28 1.43 1.77 171
Orange 620 4.84 1.61 2.00 193
Yellow 580 5.17 1.72 2.14 206
Green 530 5.66 1.89 2.34 226
Blue 470 6.38 2.13 2.64 254
Violet 420 7.14 2.38 2.95 285
Near ultraviolet 300 10.0 3.33 4.15 400
Far ultraviolet <200 >15.0 >5.00 >6.20 >598
Electromagnetic radiation is a mixture of radiation of different wavelengths and intensities. When this radiation has a wavelength inside the human visibility range (approximately from 380 nm to 740 nm), it is known as light within the (human) visible spectrum. The light's spectrum records each wavelength's intensity. The full spectrum of the incoming radiation from an object determines the visual appearance of that object, including its perceived color. As we will see, there are many more spectra than color sensations; in fact one may formally define a color to be the whole class of spectra which give rise to the same color sensation, although any such definition would vary widely among different species and also somewhat among individuals intraspecifically. A surface that diffusely reflects all wavelengths equally is perceived as white, while a dull black surface absorbs all wavelengths and does not reflect (for mirror reflection this is different: a proper mirror also reflects all wavelengths equally, but is not perceived as white, while shiny black objects do reflect). The familiar colors of the rainbow in the spectrum—named from the Latin word for appearance or apparition by Isaac Newton in 1671—contains all those colors that consist of visible light of a single wavelength only, the pure spectral or monochromatic colors. The frequencies are approximations and given in terahertz (THz). The wavelengths, valid in vacuum, are given in nanometers (nm). A list of other objects of similar size is available.

Important note

The color table should not be interpreted as a definite list – the pure spectral colors form a continuous spectrum, and how it is divided into distinct colors is a matter of taste and culture. Similarly, the intensity of a spectral color may alter its perception considerably; for example, a low-intensity orange-yellow is brown, and a low-intensity yellow-green is olive-green.

Spectral versus non-spectral colors

Most light sources are not pure spectral sources; rather they are created from mixtures of various wavelengths and intensities of light. To the human eye, however, there is a wide class of mixed-spectrum light that is perceived the same as a pure spectral color. In the table above, for instance, when your computer screen is displaying the "orange" patch, it is not emitting pure light at a fixed wavelength of around 600 nm (which is something most computer screens are unable to do). Rather, it is emitting a mixture of about two parts red to one part green light. Were you to print this page on a color printer, the orange patch on the paper, when lit with white light, would reflect yet another, more continuous spectrum. We cannot see those differences (although many animals can), and the reason has to do with the pigments that make up our color vision cells (see below). A useful quantification of this property is the dominant wavelength, which matches a wavelength of spectral light to a non-spectral source that evokes the same color perception. Dominant wavelength is the formal background for the popular concept of hue. In addition to the many light sources that can appear to be pure spectral colors but are actually mixtures, there are many color perceptions that by definition cannot be pure spectral colors due to desaturation or because they are purples (which are a mixture of red and violet light, from either end of the spectrum). Some examples of necessarily non-spectral colors are the achromatic colors (black, gray and white) and other colors such as pink, tan and magenta. See metamerism (color) for a basic introduction as to why color matching challenges exist.

Physical basis of color

A light wave can be analyzed as a superposition of sine waves, each of which has a specific frequency and wavelength. The eye gives limited information about the relative intensities of these sine waves (but not their phases — the eye is even more blind to phase than the ear, which can detect phase relationships of sounds only in certain very specific contexts). To understand which particular color perception will arise from a particular physical spectrum requires knowledge of the physiology of the retina. The human eye is also insensitive to polarization in most cases (though see Haidinger's brush), whereas some fish and mollusks can perceive it.

Color vision

Though the exact status of color is a matter of current philosophical dispute, color is arguably a psychophysical phenomenon that exists only in our minds. (See Qualia, for some of that dispute.) A "red" apple does not give off "red light", and it is misleading to think of things that we see, or of light itself, as objectively colored at all. Rather, the apple simply absorbs light of various wavelengths shining on it to different degrees, in such a way that the unabsorbed light which it reflects is perceived as red. An apple is perceived to be red only because normal human color vision perceives light with different mixes of wavelengths differently—and we have language to describe that difference. language In 1931, an international group of experts called the Commission Internationale d'Eclairage (CIE) developed a mathematical color model. The premise used by the CIE is that color is the combination of three things: a light source, an object, and an observer. The CIE tightly controlled each of these variables in an experiment that produced the measurements for the system. Although Aristotle and other ancient scientists speculated on the nature of light and color vision, it was not until Newton that light was correctly identified as the source of the color sensation. Goethe studied the theory of colors, and in 1801 Thomas Young proposed his trichromatic theory which was later refined by Hermann von Helmholtz. That theory was confirmed in the 1960s and will be described below. Hermann von Helmholtz The retina of the human eye contains three different types of color receptor cells, or cones. One type, relatively distinct from the other two, is most responsive to light that we perceive as violet, with wavelengths around 420 nm (cones of this type are sometimes called short-wavelength cones, S cones, or, most commonly but quite misleadingly, blue cones). The other two types are closely related genetically, chemically and in response. Each type is most responsive to light that we perceive as green or greenish. One of these types (sometimes called long-wavelength cones, L cones, or, misleadingly, red cones) is most sensitive to light we perceive as yellowish-green, with wavelengths around 564 nm; the other type (sometimes called middle-wavelength cones, M cones, or misleadingly green cones) is most sensitive to light perceived as green, with wavelengths around 534 nm. The term "red cones" for the long-wavelength cones is deprecated as this type is actually maximally responsive to light we perceive as greenish, albeit longer wavelength light than that which maximally excites the mid-wavelength/"green" cones. The sensitivity curves of the cones are roughly bell-shaped, and overlap considerably. The incoming signal spectrum is thus reduced by the eye to three values, sometimes called tristimulus values, representing the intensity of the response of each of the cone types. Because of the overlap between the sensitivity ranges, some combinations of responses in the three types of cone are impossible no matter what light stimulation is used. For example, it is not possible to stimulate only the mid-wavelength/"green" cones: the other cones must be stimulated to some degree at the same time, even if light of some single wavelength is used (including that to which the target cones are maximally sensitive). The set of all possible tristimulus values determines the human color space. It has been estimated that humans can distinguish roughly 10 million different colors, although the identification of a specific color is highly subjective, since even the two eyes of a single individual perceive colors slightly differently. This is discussed in more detail below. The rod system (which vision in very low light relies on exclusively) does not by itself sense differences in wavelength; therefore it is not normally implicated in color vision. But experiments have conclusively shown that in certain marginal conditions a combination of rod stimulation and cone stimulation can result in color discriminations not based on the mechanisms described above. While the mechanisms of color vision at the level of the cones in the retina are well described in terms of tristimulus values (see above), color processing and perception above that base level are organized differently. A dominant theory of the higher neural mechanisms of color vision proposes three opponent processes, or opponent channels, constructed out of the raw input from the cones: a red-green channel, a blue-yellow channel, and a black-white ("luminance") channel. This theory tries to account for the structure of our subjective color experience (see discussion below). Blue and yellow are considered complementary colors, or opposites: you could not experience a bluish yellow (or a greenish red), any more than you could experience a dark brightness or a hot coldness. The four "polar" colors proposed as extremes in the two opponent processes other than black-white have some natural claim to being called primary colors. This is in competition with various sets of three primary colors proposed as "generators" of all normal human color experience (see below).

Clinical issues

If one or more types of a person's color-sensing cones are missing or less responsive than normal to incoming light, that person has a smaller or skewed color space and is said to be color deficient. Another term frequently used is color blind, although this can be misleading; only a small fraction of color deficient individuals actually see completely in black and white, and most simply have anomalous color perception. Some kinds of color deficiency are caused by anomalies in the number or nature of cones of the various types, as just described. Others (like central or cortical achromatopsia) are caused by neural anomalies in those parts of the brain where visual processing takes place. Some animals may have more than three different types of color receptor (most marsupials, birds, reptiles, and fish; see tetrachromat, below) or fewer (most mammals; these are called dichromats and monochromats). Humans and other old-world primates are actually rather unusual in possessing three kinds of receptors. An unusual and elusive neurological condition sometimes affecting color perception is synaesthesia.

Tetrachromat

A normal human is a trichromat (from Greek: tri=three, chroma=color). In theory it may be possible for a person to have four, rather than three, distinct types of cone cell. If these four types are sufficiently distinct in spectral sensitivity and the neural processing of the input from the four types is developed, a person may be a tetrachromat (tetra=four). Such a person might have an extra and slightly different copy of either the medium- or long-wave cones. It is not clear whether such people exist or that the human brain could actually process the information from such an extra cone type separately from the standard three. However, strong evidence suggests that such people do exist, they are all female by genetic imperative, and their brains gladly adapt to use the additional information. For many species, tetrachromacy is the normal case, although the cone cells of animal tetrachromats have a very different (more evenly-spaced) spectral sensitivity distribution than those of possible human tetrachromats.

Color perception

There is an interesting phenomenon which occurs when an artist uses a limited color palette: the eye tends to compensate by seeing any grey or neutral color as the color which is missing from the color wheel. E.g.: in a limited palette consisting of red, yellow, black, and white, a mixture of yellow and black will appear as a variety of green, a mixture of red and black will appear as a variety of purple, and pure grey will appear bluish. When the eye shifts attention after viewing a color for some time, then an afterimage of the complement of that color (the color opposite to it in the color wheel) is perceived by the eye for some time wherever it moves. This effect of color perception was utilised by Vincent van Gogh, a Post-Impressionist painter.

Effect of luminosity

Note that the color experience of a given light mixture may vary with absolute luminosity, because both rods and cones are active at once in the eye, with each having different color curves, and rods taking over gradually from cones as the brightness of the scene is reduced. This effect leads to a change in color rendition with absolute illumination levels that can be summarised in the "Kruithof curve".

Cultural influences

Different cultures have different terms for colors, and may also assign some color names to slightly different parts of the spectrum, or have a different color ontology: for instance, the Han character 青 (pronounced qīng in Mandarin and aoi in Japanese) has a meaning that covers both blue and green; blue and green are traditionally considered shades of 青; In more contemporary terms, they are 藍 (lán) and 綠 (lǜ) respectively. Similarly, languages are selective when deciding which hues are split into different colors on the basis of how light or dark they are. Apart from the black-grey-white continuum, English splits some hues into several distinct colors according to lightness: such as red and pink or orange and brown. To English speakers, these pairs of colors, which are objectively no more different that light green and dark green, are conceived as totally different. An Italian will make the same red-pink and orange-brown distinctions, but will also make a further distinction between blu and azzurro, which English speakers would simply call dark and light blue. To Italian speakers, blu and azzurro are as separate as red and pink or orange and brown. Color terms evolve. It is argued that there are a limited number of universal "basic color terms" which begin to be used by individual cultures in a relatively fixed order. For example, a culture would start with only two terms, meaning roughly 'dark' (covering black, dark colors and cold colors such as blue ) and 'bright' (covering white, light colors and warm colors such as red), before adding more specific color names, in the order of red; green and/or yellow; blue; brown; and orange, pink, purple, and/or gray. Older arguments for this theory also stipulated that the acquisition and use of basic color terms further along the evolutionary order indicated a more complex culture with more highly developed technology. A somewhat dated example of a universal color categories theory is Basic Color Terms: Their Universality and Evolution (1969) by Brent Berlin and Paul Kay. A more recent example of a linguistic determinism theory might be Is color categorisation universal? New evidence from a stone-age culture (1999) by Jules Davidoff et al. The idea of linguistically determined color categories is often used as evidence for the Sapir-Whorf hypothesis (Language, Thought, and Reality (1956) by Benjamin Lee Whorf). Additionally, different colors are often associated with different emotional states, values, or groups, but these associations can vary between cultures. In one system, red is considered to motivate action; orange and purple are related to spirituality; yellow cheers; green creates cosiness and warmth; blue relaxes; and white is associated with either purity or death. These associations are described more fully in the individual color pages, and under color psychology. See also: National colors

Color constancy

The trichromatric theory discussed above is strictly true only if the whole scene seen by the eye is of one and the same color, which of course is unrealistic. In reality, the brain compares the various colors in a scene, in order to eliminate the effects of the illumination. If a scene is illuminated with one light, and then with another, as long as the difference between the light sources stays within a reasonable range, the colors of the scene will nevertheless appear constant to us. This was discovered by Edwin Land in the 1970s and led to his retinex theory of color constancy.

Contrast

Note: the following comparison requires an all-digital display setup (commonly, a laptop or DVI-connected LCD) to avoid errors caused by an unfortunate interaction between frequency response and gamma curves. Compare the visibility of the RGB primary and secondary colors against a white background:
red green blue red+green green+blue red+blue red+green+blue zero light
Again, compare variations on gray backgrounds—#7f7f7f, #5f5f5f & #9f9f9f—the eight RGB primaries are equidistant from #7f7f7f in a 3-d geometrical representation of RGB color space—a reminder of the importance of background color for color perception. Background = #7f7f7f
red green blue red+green green+blue red+blue red+green+blue zero light
And let's look at black again, for completeness. (Note that your monitor background probably is not perfectly black, as you can see by switching off the monitor.) Background = #000000
red green blue red+green green+blue red+blue red+green+blue zero light

Measurement and reproduction of color

monitor Two different light spectra which have the same effect on the three color receptors in the human eye will be perceived as the same color. This is exemplified by the white light that is emitted by fluorescent lamps, which typically has a spectrum consisting of a few narrow bands, while daylight has a continuous spectrum. The human eye cannot tell the difference between such light spectra just by looking into the light source, although reflected colors from objects can look different. (This is often exploited e.g. to make fruit or tomatoes look more brightly red in shops.) Similarly, most human color perceptions can be generated by a mixture of three colors called primaries. This is used to reproduce color scenes in photography, printing, television, and other media. There are a number of methods or color spaces for specifying a color in terms of three particular primary colors. Each method has its advantages and disadvantages depending on the particular application. No mixture of colors, though, can produce a fully pure color perceived as completely identical to a spectral color, although one can get very close for the longer wavelengths, where the chromaticity diagram above has a nearly straight edge. For example, mixing green light (530 nm) and blue light (460 nm) produces cyan light that is slightly desaturated, because response of the red color receptor would be greater to the green and blue light in the mixture than it would be to a pure cyan light at 485 nm that has the same intensity as the mixture of blue and green. Because of this, and because the primaries in color printing systems generally are not pure themselves, the colors reproduced are never perfectly saturated colors, and so spectral colors cannot be matched exactly. However, natural scenes rarely contain fully saturated colors, thus such scenes can usually be approximated well by these systems. The range of colors that can be reproduced with a given color reproduction system is called the gamut. The CIE chromaticity diagram can be used to describe the gamut. Another problem with color reproduction systems is connected with the acquisition devices, like cameras or scanners. The characteristics of the color sensors in the devices are often very far from the characteristics of the receptors in the human eye. In effect, acquisition of colors that have some special, often very "jagged", spectra caused for example by unusual lighting of the photographed scene can be relatively poor. Species that have color receptors different from humans, e. g. birds that may have four receptors, can differentiate some colors that look the same to a human. In such cases, a color reproduction system `tuned' to a human with normal color vision may give very inaccurate results for the other observers. The next problem is different color response of different devices. For color information stored and transferred in a digital form, color management technique based on color profiles attached to color data and to devices with different color response helps to avoid deformations of the reproduced colors. The technique works only for colors in gamut of the particular devices, e.g. it can still happen that your monitor is not able to show you real color of your goldfish even if your camera can receive and store the color information properly and vice versa.

Pigments and reflective media

When producing a color print or painting a surface, the applied paint changes the surface; if the surface is then illuminated with white light (which consists of equal intensities of all visible wavelengths), the reflected light will have a spectrum corresponding to the desired color. If a dab of paint looks red in white light, that is because the reflection of all non-red wavelengths is interrupted by the pigment, such that only red light is reflected into one's eye.

Structural color

Structural color is a property of some surfaces that are scored with fine parallel lines, formed of many thin parallel layers, or otherwise composed of periodic microstructures on the scale of the color's wavelength, to make a diffraction grating. The grating reflects some wavelengths more than others due to interference phenomena, causing white light to be reflected as colored light. Variations in the pattern's spacing often give rise to an iridescent effect, as seen in peacock feathers, films of oil, and mother of pearl, because the reflected color depends upon the viewing angle. Structural color is studied in the field of thin-film optics. A layman's term that describes particularly the most ordered structural colors is iridescence.

Footnotes

# The spelling color is predominant in American English, while colour is used in Commonwealth English. See our/or.

See also


- Metamerism
- Chromophore
- List of colors
- Qualia
- Color blindness
- Color temperature
- Color theory
  - Color scheme
- Colors and emblems for parties
- Political color
- Color psychology
- Synaesthesia (the mental connection, almost always arbitrary, between senses, usually involving color)
- Goethe's Theory of Colors
- The International Commission on Illumination defines colors and color spaces
- Thermochromics
- Tincture (heraldry). The colors in heraldry.

External links and sources


- [http://www.physicstoday.org/vol-55/iss-7/p43.html Comparative Article examining Goethean and Newtonian Color]
- [http://palimpsest.stanford.edu/waac/wn/wn21/wn21-3/wn21-308.html Kruithof curve citation]
- [http://www.soluxtli.com/edu13.htm Article by technical lighting manufacturer on rod/cone vision, with cites to literature]
- [http://www.angelfire.com/psy/reading/Colour.html The Psychology of Colour]
- [http://plato.stanford.edu/entries/color/ Stanford Encyclopedia of Philosophy entry]
- [http://webexhibits.org/causesofcolor/ Why are things colored?]
- [http://www.research.ibm.com/people/l/lloydt/color/color.HTM Why Should Engineers and Scientists Be Worried About Color?]
- [http://poynterextra.org/cp/colorproject/color.html Color, Contrast & Dimension in News Design] Category:Color Category:Image processing Category:Vision ko:색 ja:色 simple:Color

1 E-7 m

To help compare different orders of magnitude this page lists lengths between 10-7 and 10-6 m (100 nm and 1 µm).
- Distances shorter than 100 nm
- 100 nm — greatest particle size that can fit through a surgical mask
- 120 nm — greatest particle size that can fit through a ULPA filter [http://www.ristenbatt.com/filt_eff.htm]
- 125 nm — standard depth of pits on compact discs (width: 500 nm, length: 850 nm to 3.5 µm)
- 180 nm — typical length of the rabies virus
- 200 nm — typical size of a Mycoplasma bacterium, among the smallest bacteria
- 280 nm — near ultraviolet wavelength
- 300 nm — greatest particle size that can fit through a HEPA filter
- 380-420 nm — wavelength of violet light (see color and optical spectrum)
- 420-440 nm — wavelength of indigo light
- 440-500 nm — wavelength of blue light
- 500-520 nm — wavelength of cyan light
- 520-565 nm — wavelength of green light
- 565-590 nm — wavelength of yellow light
- 590-625 nm — wavelength of orange light
- 625-740 nm — wavelength of red light
- Distances longer than 1 µm

See also


- Orders of magnitude (length) -07 ja:1 E-7 m

Nanometer

To help compare different orders of magnitudes this page lists lengths between 10-9 m (metre) and 10-8 m (1 nm and 10 nm).
- Lengths shorter than 1 nm
- 1 nm = 1 nanometre = 1000 picometres = 10 Ångströms
- is roughly the length of a sucrose molecule, calculated by Albert Einstein.
- 1.1 nm — diameter of a single-walled carbon nanotube
- 2 nm — diameter of DNA helix
- 3 nm — flying height of the head of a hard disk
- Lengths longer than 10 nm

See also


- Orders of magnitude (length) -09 ja:1 E-9 m

Primary color

:This page is about actual colors. For the political book and movie, see Primary Colors A primary color (or colour) is a color that cannot be created by mixing other colors in the gamut of a given color space. Primary colors may themselves be mixed to produce most of the colors in a given color space: mixing two primary colors produces what is generally called a secondary color, mixing a secondary with a primary produces what is sometimes called a tertiary color. Traditionally, the colors red, yellow, and blue are considered to be primary pigments in the art world. However those colors are not the same hue as the "red", "yellow" and "blue" used in alternate color systems. Many modern applications use primary additive colors of red, green and blue; and the primary pigments of magenta, yellow, and cyan. If the color space is considered as a vector space, the primary colors can be regarded as a set of basis vectors for that space.

Biological basis

Primary colors are not a physical but rather a biological concept, based on the physiological response of the human eye to light. The human eye contains receptors called cones which normally respond to red, green, and blue light. Humans and other species with three such types of color receptors are known as trichromats. Although the peak responsivities of the cones do not occur exactly at the red, green and blue frequencies, those three colors are chosen as primary because they provide a wide gamut, making it possible to almost independently stimulate the three color receptors. To generate optimal color ranges for species other than humans, other additive primary colors would have to be used. For species known as tetrachromats with four different color receptors, one would use four primary colors. Many birds and marsupials are tetrachromats and it has been suggested that some female humans are born as tetrachromats as well, having an extra receptor for yellow. On the other hand, most mammals have only two types of color receptors and are therefore dichromats; to them, there are only two primary colors.

Additive primaries

dichromat Media that combine emitted lights to create the sensation of a range of colors are using the additive color system. Television is the most common use of this. The Additive primaries are red, green, and blue. Because of the response curves of the three different color receptors in the human eye, these colors are optimal in the sense that the largest range of colors (gamut) visible by humans can be generated by mixing light of these colors. Additive mixing of red and green light, produce shades of yellow or orange. Mixing green and blue produces shades of cyan, and mixing red and blue produces shades of purple and magenta. Mixing equal proportions of the additive primaries results in shades of grey; when all three colors are fully saturated, the result is white. The color space that is generated is called the RGB ("red, green, blue") color space

Subtractive primaries

Media that use reflected light and colorants to produce colors are using the subtractive color method of color mixing. In the printing industry, to produce the varying colors, apply the subtractive primaries yellow, cyan, and magenta together in varying amounts. Subtractive color works best when the surface (or paper) is white, or close to it. magenta Mixing yellow and cyan produces shades of green; mixing yellow with magenta produces shades of red, and mixing magenta with cyan produces shades of blue. In theory, mixing equal amounts of all three pigments should produce shades of grey, resulting in black when all three are fully saturated, but in practice they tend to produce muddy brown colors. For this reason, a fourth "primary" pigment, black, is often used in addition to the cyan, magenta, and yellow colors. The color space generated is the so-called CMYK color space. (standing for "Cyan, Magenta, Yellow, and Black - K is used to represent black as 'B' could be confused with 'Blue'"). In practice, mixtures of actual materials like paint tend to be less precise. Brighter, or more specific colors can be created using natural pigments instead of mixing, and natural properties of pigments can interfere with the mixing. For example, mixing magenta and green in acrylic creates a dark cyan - something which would not happen if the mixing process were perfectly subtractive. In the subtractive model, adding white to a color does not change its hue but does reduce its saturation. For a more detailed and extensive treatment of color, see color. See printing

See Also


- Secondary color
- Tertiary color

External links


- [http://www.newton.dep.anl.gov/askasci/phy00/phy00871.htm Ask A Scientist: Primary Colors]
- [http://hyperphysics.phy-astr.gsu.edu/hbase/vision/colcon.html#c1 The Color-Sensitive Cones at HyperPhysics]
- [http://handprint.com/HP/WCL/wcolor.html Handprint.com : do "primary" colors exist?] - a very comprehensive site on color primaries, color perception, color psychology, color theory, and color mixing
- [http://www.cecs.csulb.edu/~jewett/colors/index.html Color Tutorial] Category:Color

Cyan

:This article is about the color. For other senses of this word see cyan (disambiguation). Cyan is a color made by mixing equal amounts of green and blue light (it also is a pure spectral color). As such, cyan is the complement of red: cyan pigments absorb red light. Cyan is sometimes called blue-green or turquoise and often goes undistinguished from light blue. Cyan is often referred to as "Electric Blue". Cyan is one of the common inks used in four-color printing, along with magenta, yellow, and black; this set of colors is referred to as CMYK. Note that while both of these colors are called cyan they are actually substantially different from one another. Cyan printing ink is much less vivid--indeed, CMYK printing technology cannot accurately reproduce pure cyan (100% blue + 100% green) on paper. paper

See also


- List of colors
- ja:シアン (色) nb:Cyan

Magenta

:This article is about the dye color magenta. For other uses of the word, see Magenta (disambiguation). Magenta is a color made up of red and blue light. A common precise definition for the color does not exist--however, in printing, the color is made up of equal parts of red and blue. As such, this shade magenta is the complement of green: magenta pigments absorb green light. In any case, it is not a spectral color: the hue cannot be generated by light of a single wavelength. Along with yellow and cyan, a magenta of equal amounts of red and blue constitutes the three subtractive primary colors. Magenta, properly speaking, is a variant of purple. A specific shade of magenta, fuchsia, was assigned as an alias for the RGB code of magenta on a list of standarized web colors. In general use, magenta itself can vary from the deep pink color shown below to the purple shade shown above. This specific variant of magenta is also called Fuchsia after the color of the flowers of the same name, named after Leonhart Fuchs. Leonhart Fuchs

History

Magenta was one of the first aniline dyes, discovered shortly after the Battle of Magenta (1859), which occurred near the town of Magenta in northern Italy. The color is named after the battle, and hence indirectly after the town. If the visible spectrum is wrapped to form a color wheel, magenta appears between red and blue: center
center

See also


- List of colors Category:Shades of violet Category:Shades of red ja:マゼンタ

Tap (valve)

A tap is a valve for controlling the release of a liquid or gas. In British English the word is used for any everyday type of valve, particularly the fittings on bathtubs and sinks that would be called faucets elsewhere. In American English the usage is sometimes more specialised, with the term tap restricted to uses such as beer taps and the word "faucet" used for cold water outlets; although some Americans use "tap" in the broader sense as well.

Water taps

American English Water for baths, sinks and basins can be provided by separate hot and cold taps; this arrangement is common in the UK, particularly in bathrooms. In kitchens, and in the US and many other places, mixer taps are used instead. This is a single, more complex, valve whose handle moves up and down to control the amount of water flow and from side to side to control the temperature of the water (achieved by mixing the hot and cold water together). Latest designs do this using a built in thermostat. If separate taps are fitted, it may not be immediately clear which tap is hot and which is cold. The hot tap generally has a red indicator and/or be labeled H or Hot. The cold tap tends to have a blue or green indicator and/or be labeled C or Cold. (Note that the French for 'hot' is chaud, which starts with a 'C'.) Mixer taps may have a red-blue stripe or arrows indicating which side will give hot and which cold. In some countries there is a 'standard' arrangement of hot/cold taps: for example in the United States the hot tap is generally on the left. This convention applies in the UK too, but many installations exist where it has been ignored.

Beer taps

While in other contexts, depending on location, a "tap" may be a "faucet", "valve" or "spigot", the use of "tap" for beer is almost universal. This may be because the word was originally coined for the wooden valve in traditional barrels. A "beer tap" now may be one of several items: ; Pressure-dispense bar tap : Almost universally in modern times, bulk beer is supplied in kegs that are served with the aid of external pressure. In a normal bar dispense system, this pressure comes from a cylinder of carbon dioxide (or occasionally nitrogen) which forces the beer out of the keg and up a narrow tube to the bar. At the end of this tube is a valve built into a fixture (usually somewhat decorative) on the bar. This is the beer tap, and opening it with a small lever causes beer, pushed by the gas from the cylinder, to flow into the glass. ; Portable keg tap : Sometimes, beer kegs designed to be connected to the above system are instead used on their own, perhaps at a party or outdoor event. In this case, a self-contained portable tap is required that allows beer to be served straight from the keg. Because the keg system uses pressure to force the beer up and out of the keg, these taps must have a means of supplying it. The typical "picnic tap" uses a hand pump to push air into the keg; this will cause the beer to spoil faster but is perfectly acceptable when it will be consumed in a short time. Portable taps with small CO2 cylinders are also available. nitrogen ; Cask beer tap : Beers brewed and served in the traditional way (typically real ale) do not use artificial gas. Taps for cask beer are simple on-off valves that are hammered into the end of the cask (see keystone for details). When beer is served directly from the cask ("by gravity"), as at beer festivals and some pubs, it simply flows out of the tap and into the glass. When the cask is stored in the cellar and served from the bar, as in most pubs, the beer line is screwed onto the tap and the beer is sucked through it by a hand-operated low-pressure pump on the bar. The taps used are the same, and in beer-line setups the first pint is often poured from the cask as for "gravity", for tasting, before the line is connected. Cask beer taps can be brass (now discouraged for fear of lead contamination), stainless steel (good, but expensive), plastic (acceptable, and cheaper), and wood (to be avoided if possible).

Gas taps

keystone Although a gas tap may be a valve that releases any gas, the word is most commonly used to refer to taps that control the flow of natural gas in the home (for gas fires) or in school science laboratories (for Bunsen burners).

Physics of taps

Most water and gas taps have adjustable flow. Turning the knob or working the lever sets the flow rate by adjusting the size of an opening in the valve assembly, giving rise to choked flow through the narrow opening in the valve. The choked flow rate is independent of the viscosity or temperature of the fluid or gas in the pipe, and depends only weakly on the supply pressure, so that flow rate is stable at a given setting. At intermediate flow settings the pressure at the valve restriction drops nearly to zero from the venturi effect; in water taps, this causes the water to boil momentarily at room temperature as it passes through the restriction. Bubbles of cool water vapor form and collapse at the restriction, causing the familiar hissing sound. At very low flow settings, the viscosity of the water becomes important and the pressure drop (and hissing noise) vanish; at full flow settings, parasitic drag in the pipes becomes important and the water again becomes quiet. Most taps use a soft washer which is screwed down onto a seat in order to stop the flow. This is called a "globe valve" in engineering and, while it gives a leak-proof seal and good fine adjustment of flow, the tortuous S-shaped path the water is forced to follow offers a significant obstruction to the flow. For high pressure domestic water systems this does not matter, but for low pressure systems where flowrate is important, such as a shower fed by a storage tank, a "stop tap" or, in engineering terms, a "gate valve" is preferred. This uses a metal disc the same diameter as the pipe which is screwed into place perpendicularly to the flow, cutting it off. There is no resistance to flow when the tap is fully open, but this type of tap rarely gives a perfect seal when closed. In the UK the latter type of tap normally has a wheel-shaped handle rather than a crutch or capstan handle. One reason that most beer taps are not designed for adjustable flow is that the beer itself is damaged by the pressure drop in a choked-flow valve: holding a beer tap partially open causes the beer to foam vigorously, ruining the pour. Category:Valves ja:蛇口

Firefighter

hood should be tucked inside the turnout jacket to protect the head and neck from superheated environments.]] A firefighter is a person who is trained and equipped to put out fires, rescue people, and in some areas provide emergency medical services. The fire service, also known in some countries as the fire brigade or fire department, is one of the emergency services. Firefighters are sometimes referred to as firemen, although women have increasingly joined firefighting units. emergency services Fire fighting is the process and profession of extinguishing fires. Firefighting is important in urban areas, where firefighters are on constant standby, in wildland areas, and on board ships. Not all firefighters are paid for their services. In some countries, including the United States, Canada, Finland, Australia, and New Zealand, there are often paid, or professional, firefighters working alongside volunteer firefighters. In the United Kingdom and Ireland, the use of retained firefighters (who are part-time, but are paid when on duty) rather than volunteers is standard. The three main goals in firefighting are the protection of life, the environment and property, in that order. When a life is not in danger, a firefighter must weigh the costs and benefits of protecting property and the environment. Is it logical to risk your life in an attempt to put the fire out in a gasoline storage warehouse or would it be more productive and safe to evacuate the area and prevent the explosion from harming anyone? This is the core of a firefighter's thought process as they evaluate any and all situations. Of course when a life is at risk, all attempts are made to save it.

Fire-fighting skills

Note: this mostly discusses structural firefighting. See wildfire for a discussion of forest fires. Firefighting has several basic skills: prevention, self-preservation, rescue, preservation of property and fire control. Firefighting is further broken down into skills which include size-up, extinguishment, ventilation, and salvage and overhaul. Search and Rescue, which has already been mentioned, is performed early in any fire scenario and many times is in unison with extinguishment and ventilation.

Prevention

Prevention attempts to ensure that no place simultaneously has sufficient heat, fuel and air to allow ignition and combustion. Most prevention programs are directed at controlling the energy of activation (heat). Fire suppression sprinkler systems have a proven record for controlling and extinguishing unwanted fires. Many fire officials recommend that every building, including residences, have sprinklers. Correctly working sprinklers in a residence greatly reduce the risk of death from a fire. With the small rooms typical of a residence, one or two sprinklers can cover most rooms. In addition, a major duty of fire services is the regular inspection of buildings to ensure they are up to the current building fire codes to ensure they are able to resist fire damage.

Self-preservation

Self-preservation is critical. The basic technique firefighters use is to know where they are, and to avoid hazards. Current standards in the United States recommend that firefighters work in teams, using two-in, two-out whenever in an IDLH (Immediately Dangerous to Life or Health) environment. Tools are generally carried at all times, and a special device called a PASS device is commonly worn to alert others when a firefighter stops moving for a specified period of time (usually from 10-30 seconds depending on manufacturer). Breathing apparatus known as the SCBA is worn to protect against smoke inhalation and toxic fumes. In the United States, the National Fire Protection Association (NFPA) sets a number of standards for firefighters. These standards may be adopted as law by state or local governments, or enforced by the firefighting organizations on their own.

Rescue

Rescue consists of searching, and then removing people that are alive. Animals may also be recovered, if resources and conditions permit. Generally triage and first aid are performed outside. The general form of rescue is to shuffle through the structure with the right hand against the wall, or utilizing a tool. Many fire departments follow a two-in, two-out rule, and in a large room the second person would follow behind the first, usually on their immediate left. This is called a right hand search. There is also a left hand search, which is the same thing except the right and left are reversed. Rescuers must remember to search beds and cupboards, and to identify themselves to victims. Many children are very frightened of fire-fighters in breathing masks. Rescue may also involve the extrication of victims of motor vehicle accidents. Here firefighters use spreaders, cutters, and hydraulic rams, tools more commonly known as the Jaws of Life. More technical forms of rescue include subsets such as rope rescue, swiftwater rescue, confined space rescue, and trench rescue. These types of rescue are often extremely hazardous and physically demanding. They also require extensive technical training.

Property

Buildings that are made of fuel, such as frame buildings, are different from fire-proof buildings such as concrete high-rises. Generally, the fire in a fire-proof building can be limited to a floor. Other floors can be safe simply by preventing smoke inhalation and damage. A burnable building must be evacuated. Property preservation is a great help to people. Most fires can be limited to burning only the upper part of a frame structure. If possible, gas, electricity and water should be turned off during the search, and all movable property should be tipped into the middle of a room and covered with a heavy cloth tarp. This reduces damage from water, smoke and burning embers. If the structure doesn't catch, it's very helpful to ventilate it to reduce smoke damage.

Fire control

Main article: Fire control Fire control Fire control consists of depriving a fire of fuel, oxygen or heat. Firefighters are equipped with a wide variety of equipment to accomplish this task. Some of their tools include extrication equipment, ladder trucks, tanker trucks, pumper trucks, and ambulances. Very frequent training and refresher training is required. heat

History of fire brigades

The history of organized combatting of structural fires dates back at least to ancient Egypt where hand-operated pumps may have been employed to extinguish fires. However, such attempts could be of limited value given the large structural conflagrations that could sweep through Rome and other cities. The Roman fire brigade (Vigiles) was formed in AD 6 by Augustus to combat fires using bucket brigades and pumps, as well as poles, hooks and even ballistae to tear down buildings in advance of the flames. It is generally thought that this is where the "hook" in "hook and ladder company" comes from. The Vigiles patrolled the streets of Rome to watch for fires and served as the police force. Rome suffered a number of serious fires, most notably the fire that started near the Circus Maximus on 19 July AD 64 and eventually destroyed two thirds of Rome. The Emperor Nero was blamed for the conflagration, and may in fact have allowed the fire to burn. At least one Roman may have become very rich from this fire, buying properties in advance of the flames and using teams of slaves in attempts to defend his recent acquisitions from being consumed. Another great city that experienced such a need for organized fire control was London, which suffered great fires in 798, 982 and 989. Little is known about the development of firefighting in Europe until after the Great Fire of London in 1666. It started in a baker's shop on Pudding Lane, consumed about two square miles (5 km²) of the city, leaving tens of thousands homeless. Prior to this fire, London had no organized fire protection system. Afterwards, insurance companies formed private fire brigades to protect their clients’ property. Insurance brigades would only fight fires at buildings the company insured. These buildings were identified by a badge or sign. Still, it was not until 1672 that the Dutch inventor Jan Van der Heiden invented the firehose. Constructed of flexible leather and coupled every 50 feet (15 m) with brass fittings, the length and connections remain the standard to this day. Meanwhile, in America, Jamestown, Virginia had been virtually destroyed in a fire in January, 1608. Fire "wardens" were appointed in New Amsterdam in 1648. Wardens were to patrol the cities to inspect chimneys. "Rattle Watches" were performed at night by eight appointees, who were to rouse citizens to fight fires by bucket brigade if necessary. In Boston, serious fires in 1653 and 1676 had inspired the city to take greater measures towards combatting fire. The fire engine was developed by Richard Newsham of London in 1725. Pulled as a cart to the fire, these manual pumps were manned by teams of men and could deliver up to 160 gallons per minute (12 L/s) at up to 120 feet (40 m). Benjamin Franklin created the Union Fire Company in 1736 in Philadelphia, the first volunteer fire company in America. There were no full-time paid firefighters in America until 1850. Even after the formation of paid fire companies in the United States, there were disagreements and often fights over territory. New York City companies were famous for sending runners out to fires with a large barrel to cover the hydrant closest to the fire in advance of the engines. Often fights would break out between the runners and even the responding fire companies for the right to fight the fire and receive the insurance money that would be paid to the company that fought it. Napoleon Bonaparte is generally attributed as creating the first "professional" firefighters, known as Sapeurs-Pompiers, from the French Army. Created under the Commandant of Engineers in 1810, the company was organized after a fire at the ballroom in the Austrian Embassy in Paris which injured several dignitaries. In the UK, [http://www.lbfire.org.uk organized firefighting arrived in Edinburgh, Scotland], when the Edinburgh Fire Engine Establishment was formed in 1824, led by James Braidwood. London followed in 1832 with the London Fire Engine Establishment. The first horse-drawn steam engine for fighting fires was invented in 1829, but not accepted in structural firefighting until 1860, and ignored for another two years afterwards. Internal combustion engine fire engines arrived in 1907, built in the United States, leading to the decline and disappearance of steam engines by 1925. Today, fire and rescue remains a patchwork of paid and volunteer responders. Typically, fire services in rural areas consist of volunteers while full-time organizations dominate cities and urban areas, although there are exceptions.

National information

France

French firefighters are called Sapeurs-Pompiers, and reflecting the rural nature of much of the country (wide areas with low density of population), the Volunteer Fire brigade (SPV, sapeur-pompier volontaire), with over 190,000 firefighters is the largest firefighting force in France. In addition to being called out from work to attend an incident, they may be on standby at firestations outside their working hours; the intervention and attending hours are paid by the session. The volunteer firebrigade is also a way to promote the culture of civil defense and of solidarity amongst the population. The Professional Fire Brigade (SPP, sapeur-pompier professionnel) numbers over 30,000 firefighters, employed by the départements and working on shifts. In some towns there is a mixture of professionals and volunteers, in others only one or the other. In Paris and Marseille, the fire brigades are made up of military personnel, but under the control of the Ministry of the Interior in a similar way to the Gendarmes. The Paris Fire Brigade (BSPP) has around 7,000 firefighters, and the Marseille Marine Fire Battalion (BMPM) has over 2,000. French firefighters tackle over 3.6 million incidents each year:
- 10% fires,
- 10% traffic accidents (freeing the casualties and prehospital care as first responders),
- 59% other help to people (mainly prehospital care as first responders),
- 21% other incidents (gas escapes, stuck elevators, etc). With the SAMU (French EMS), they are the backbone of the French civil defense.

Germany

civil defense] German fire brigades (Feuerwehr) are organized on a town/village basis, with each town having at least one brigade. In Germany there are about 25,000 fire departments - 24,000 volunteer fire departments (Freiwillige Feuerwehr), 800 private fire departments (Werkfeuerwehr; which mostly protect large industrial complexes) and 100 public fire departments (Berufsfeuerwehr; in the larger towns and cities). These have a total of 1,300,000 active fire fighters. German fire departments are often very well-equipped. For further information read the article in the German Wikipedia or at least have a look at the article "fire engine" here in the English Wikipedia.

the Hong Kong SAR, People's Republic of China

fire engine The Hong Kong Fire Services Department (HKFSD) not only has firefighters, but Ambulanceman/Ambulancewoman. As of 14/5/2005, there are 8,675 uniformed personnel (including ambulanceman/ambulancewoman) and 676 civilian members. The head of HKFSD is called Director but not Commissioner. Assisted by the Deputy Director, Director of the HKFSD is the head of three Operational Fire Commands: Hong Kong, Kowloon and N.T.(i.e. The three Districts). Each of the Commands is under the control of the Chief Fire Officer(CFO). In reality, there is one additional Command : The Heartquarters(HQ), which is under control of the CFO(HQ). See [http://www.hkfsd.gov.hk/home/eng/index.html for more information]

Spain

Spanish firefighters are famous for their collaboration with Third World countries. They are led by Jorge de Miguel San Martin, the chief of staff of the Spanish fire department.

United Kingdom

Main article: Fire brigades in the United Kingdom The fire brigades in England are organised on a county basis, with each post-1974 county having its own brigade. In Scotland and Wales they are on a regional basis, with eight and three brigades respectively. Northern Ireland has a single brigade, the Northern Ireland Fire Brigade. In rural areas, there are often fire stations manned by part-time retained firefighters. In addition there are a number of independent fire brigades, such as the Peterborough volunteers, the Downe House School brigade and those run by large industrial concerns. As well as responding to fires and such like, British fire brigades also have a legal obligation (in the Fire and Rescue Services Act 2004) to respond to any emergency, which can pose a threat to life, and the environment. Many of these legal changes have come about as a result of the increased terrorist threat and recent industrial action. More information can be found [http://www.fire-uk.org/ here]. Information on fire safety issued by the Office of the Deputy Prime Minister can be found [http://www.firekills.gov.uk here].

Miscellaneous

In popular literature, firefighters are usually depicted with Dalmatian dogs. This breed originated in southern Europe to assist with herding livestock and run along with horses, and in the days of horse-drawn fire apparatus the horses were usually released on arrival at the fire and the Dalmatians would lead/direct the horses to a safe place to wait until the fire was out. Dalmatians also filled the role of protecting the horses` feet from other dogs as the fire equipment was being transported to the fire scene. Firefighters often refer to law enforcement officers as "blue canaries", tongue in cheek, because one can evaluate a hazardous material incident from a distance by watching the police—they always drive right up to the scene, and if their cars don't stall, it's not an oxygen deprived atmosphere. Then they jump out of their vehicle, and if they don't die, it's not a poisonous atmosphere. Then they start lighting flares, and if there isn't an explosion, it's not an explosive atmosphere, and if the car doesn't melt into a puddle, the atmosphere isn't corrosive, and the firefighters can move in. This is a reference to the practice of using canaries to test for oxygen depletion in early mines. Another tongue in cheek reference is the "New Jersey Taste Test", where a firefighter or police officer walks to a hazardous material, dips up a little with their finger, then tastes it. See "blue canaries" above. The "Hazmat Rule of Thumb": If you can hold your thumb up and still see the incident, you are still too close. Roughly 72% of fire departments in the United States are all volunteer. Fire hydrants are referred to in some regions as "fire plugs". This term originated with the advent of the first municipal water systems, in which the "pipes" were often actually hollowed out logs. For firefighting purposes, cobblestones were removed from the street or sidewalk to access the wooden water main. A hole was drilled into the log and then "plugged" with a wooden plug or stake. In the event of a fire, firefighters would locate the "fire plug" and unplug it to obtain water.

See also


- Arlington County Fire Department
- Bushfire
- FDNY
- Fire/Burglar alarms
- Fire engine
- Fire station
- Fireboat
- Fire safety
- Glossary of firefighting equipment
- Glossary of firefighting terms
- Glossary of wildland fire terms
- LAFD
- List of historic fires
- Smokejumper
- Smoke detector
- Water tender Category:Protective service occupations
- ja:消防

Photo Reference

The photograph of the firefighter with "61" on his helmet is courtesy of http://www.local1800.org IAFF Local 1800 Clinton Township Firefighters Association and http://www.clintontwp-columbus.org/fire.htm Clinton Township Division of Fire.

Stop sign

A stop sign is a traffic sign, usually erected at road junctions, that instructs drivers to make a brief and temporary, but complete, stop upon reaching it, and then to proceed only if the way ahead is clear. Stop signs are not generally required at every intersection, but they are often used to control conflicting traffic movements at dangerous intersections which are not busy enough to justify the installation of either traffic lights or, especially in Europe, a roundabout. In the United States and Canada they are commonly used in residential areas, and near places where children play, as a general traffic calming measure. In these countries it is not uncommon for stop signs to be erected on all three or four intersecting roads. The intentional removal of stop signs from their posted locations is a crime in most U.S. states. Fatal accidents caused by someone removing a stop sign on purpose could also result in manslaughter charges against the offender. The purposeful removal of stop signs began in the 1980s as a college prank and, today, one may find illegally obtained stop signs hanging in the occasional college dorm rooms. Anyone who wishes to legitimately obtain a stop sign for home display can purchase one new from a traffic supply house for about US$75. US$ The following remarks concerning the right-of-way rules at intersections with multiple stop signs apply to the United States and Canada:
- Generally, the driver who stops first continues first.
- If two drivers stop simultaneously at stop signs at a single intersection, the rule is that the car that comes to a complete stop first has the right of way. Common sense applies.
- Stop signs may be augmented with additional information such as a plate bearing the legend "4-way stop". This is important, because a driver accustomed to negotiating four-way stops may falsely believe when encountering a two-way stop that cross traffic is required to stop. Since the first car to stop has the right of way at a four-way stop, this driver may believe that it is safe to turn in front of the oncoming traffic. Therefore, if there is only a plain stop sign, the assumption has to be that cross traffic will not stop. "4-way stop" plates are provided on the fail-safe principle that if they are missing (through disrepair, vandalism, etc.) the "more dangerous" message is given. Stop signs, usually based on the American design, are found all over the world, although in Europe they tend to be used far more sparingly than in North America, generally being restricted (on the principle that "familiarity breeds contempt") to situations where coming to a dead stop is absolutely essential because of poor visibility at the intersection concerned. In all countries, the driver must actually stop even if no vehicles or pedestrians are visible. However, some drivers practice the illegal manoeuvre known as a rolling or "California" stop: slowing down significantly but not stopping completely at the sign. Yield signs ("Give way" signs in the UK, Australia, and New Zealand), on the other hand, require the driver only to slow and prepare to stop, but do not require an actual stop if the way ahead is clear.

History

New Zealand Stop signs originated in Detroit, Michigan in 1915. The first had black letters on a white background and were somewhat smaller than the modern one. As they became more widespread, a committee supported by the American Association of State Highway and Transportation Officials (AASHO) met in 1922 to standardize them, and it selected the octagonal shape that has been used in the U.S. ever since. The unique eight-sided shape of the sign allows drivers facing the back of the sign to identify that oncoming drivers have a stop sign and prevent confusion with other traffic signs. In 1924, the sign changed to black on yellow, the predominant color until 1954. Another competing group, the NCSHS, simultaneously advocated an even smaller, red-on-yellow stop sign. All of these signs were typically mounted only two or three feet above the ground. These two organizations conflicted but eventually combined into the Joint Committee on Uniform Traffic Control Devices, which in 1935 published the famous Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) detailing the stop sign's appearance. The MUTCD stop sign was altered eight times between 1935 and 1971, mostly dealing with its reflectorization and its mounting height; the most drastic change came in 1954, when the sign gained its white-on-red color. Red is also the color for stop on traffic signals, unifying red as stop signal for drivers worldwide. The mounting height reached its current level of 2.1 m (7 ft) in 1971. Although already widespread, use of the MUTCD stop sign passed into law in the United States in 1966. They were later adopted by the European Union as part of their effort to standardize road travel across member countries.

Different (Non-English) variants

Although English-speaking and European Union countries use the original word "STOP" on stop signs, most countries, and sometimes even smaller political districts, prefer to use a roughly equivalent word in their primary language instead; its appearance is otherwise the same of white text on a red octagon. The few known exceptions include Israel (which uses a solid white hand on a red octagon) and Japan (which uses the local word for Stop in white type on an inverted solid red triangle). Although the word used isn't universally standardized, some commonly seen examples are: European Union

See also


- Traffic sign
- Road safety
- Rules of the road

External links


- [http://signalfan.freeservers.com/road%20signs/stopsign.htm History of the Stop Sign in America]
- [http://www.geog.okstate.edu/users/lightfoot/stop/page/main.htm Stop Signs from Around the World]
- [http://www.mycrazyhobby.com/stop/ A Collection of Stop and Yield Signs] Category:Traffic signs

School bus

by Wayne dealer Jeff Davis at Virginia State Capitol]] A school bus is a bus used to transport children and adolescents to and from school. The first school bus was horse-drawn, introduced in 1827 by George Shillibeer for a Quaker school at Abney Park in Stoke Newington, London, and was designed to carry twenty-five children. Since then, school buses of many types have become widespread, and motorised, and are used in all parts of the world. Some countries have specially built, painted and equipped school buses. In Canada and the United States they are required to comply with different safety standards than conventional passenger vans and buses. They are commonly painted an orangey-yellow color (officially known as "National School Bus Glossy Yellow") for purposes of visibility and safety and equipped with specialized traffic warning devices. Most used in recent years have been diesel-powered. Full-size school buses can seat forty-five to seventy passengers or even more, but in many districts smaller vehicles are used as well. Such smaller vehicles are commonly known as "short buses", and are often associated with developmentally handicapped programs. Some U.S. school districts purchase the buses and hire their own drivers, while others engage the service of school bus contractors such as Laidlaw to perform this function. School buses in the UK in almost all cases are contracted out to local bus companies. Elsewhere in Europe school bus services are contracted to local bus companies, which use regional buses that operate on regular lines at other times, or in some case older regional buses.

School buses in the U.S.and Canada

Early modes: wagons, kid hacks

Wayne Works, predecessor of Wayne Corporation, was founded in the United States of America in 1837. By 1886, and possibly earlier, it is known that Wayne Works was making horse-drawn school carriages which many people referred to as "school hacks," "school cars," "school trucks," or "kid hacks." ("hack" was a term for certain types of horse-drawn carriages.)

Motorized vehicles

In 1914, Wayne Works dropped a wooden kid hack onto an automobile chassis, creating a predecessor to the modern motor school bus. In the bodies for school transportation the company produced through this era, passengers sat on perimeter seating, facing the center rather than the front of the bus. Entry and egress was through a door at the rear, a design begun in non-motorized days so as not to startle the horses. This was possibly a precursor to the modern rear emergency door commonly found on modern school buses. In 1927, Blue Bird Body Company and Wayne Works began building all-steel bus bodies, followed by others by 1935. In the 1930s, the school bus bodies of Wayne Works began to include a group of heavy-duty "collision rails" or "guard rails" as an added safety feature. Early school buses primarily served rural areas where it was deemed impractical for the young students to walk the distances necessary to get back and forth from school on their own, and were sometimes no more than a truck with perhaps a tarpaulin stretched over the truck bed. Wayne Works was one of the earliest school bus companies to offer glass in place of the standard canvas curtains in the passenger area long before many "school" bus companies did in the early 1930s.

Experiments with transit-style school buses

rural In the 1930s, Wayne Works, Crown Coach of California, and other school bus body companies manufactured some transit-style school buses, that is, types with a more or less flat front-end design (known in modern times as "type D" school buses). Crown Coach built the first heavy duty, high capacity, transit style school coach in 1932, and is considered to have made the most transit buses during this period, as many California school districts operated in terrain requiring heavy duty vehicles. In 1950, Albert L. Luce, founder of the Blue Bird Body Company, developed a transit style design which evolved into the Blue Bird All-American, generally considered the first successful east coast school bus transit design. However, the "conventional" design, with a truck type hood and f