2018年3月31日星期六

Pink color in science and nature

Pink is a pale red color that is named after a flower of the same name. It was first used as a color name in the late 17th century. According to surveys in Europe and the United States, pink is the color most often associated with charm, politeness, sensitivity, tenderness, sweetness, childhood, femininity and the romantic. It is associated with chastity and innocence when combined with white, but associated with eroticism and seduction when combined with purple or black.

Science and nature

Optics
Red is the only color whose lighter shades have a different name, pink, than the color itself. In optics, the word "pink" can refer to any of the pale shades of colors between bluish red to red in hue, of medium to high lightness, and of low to moderate saturation. Although pink is generally considered a tint of red, the hues of most shades of pink are slightly bluish, and lie between red and magenta. A few variations of pink, such as salmon color, lean toward orange.

Why sunrises and sunsets sometimes look pink
As a ray of white sunlight travels through the atmosphere, some of the colors are scattered out of the beam by air molecules and airborne particles. This is called Rayleigh scattering. Colors with a shorter wavelength, such as blue and green, scatter more strongly, and are removed from the light that finally reaches the eye. At sunrise and sunset, when the path of the sunlight through the atmosphere to the eye is longest, the blue and green components are removed almost completely, leaving the longer wavelength orange, red and pink light. The remaining pinkish sunlight can also be scattered by cloud droplets and other relatively large particles, which give the sky above the horizon a pink or reddish glow.

Why cooked beef, cured ham, steamed shrimp and salmon are pink
Raw beef is red, because the muscles of vertebrate animals, such as cows and pigs, contain a protein called myoglobin, which binds oxygen and iron atoms. When beef is cooked, the myoglobin proteins undergo oxidation, and gradually turn from red to pink to brown; that is, from rare to medium to well-done. Pork contains less myoglobin than beef and therefore is less red; when heated, it changes from pinkish-red to less pink to tan or white.

Ham, though it contains myoglobins like beef, undergoes a different transformation. Traditional hams, such as prosciutto, are made by taking the hind leg or thigh of a pig, covering it with sea salt, which removes the moisture content, and then letting it dry or cure for as long as two years. The salt (sodium nitrate) permits the ham to retain its original pink color, even when dried out. Supermarket hams are made by a different and faster process; they are brined, or infused with a salt-water solution, containing sodium nitrite, which transfers nitric oxide, which bonds with the myoglobin to form the traditional pink cured ham color.

The shells and flesh of crustaceans such as crabs, lobsters and shrimp contain a pink carotenoid pigment called astaxanthin. Their shells, naturally blue-green, turn pink or red when cooked. The flesh of the salmon also contains astaxanthins, which makes it pink. Farm-bred salmon are sometimes fed these pigments to improve their pinkness, and it is sometimes also used to enhance the color of egg yolks.

Roast beef gets its distinctive pink color from myoglobin, which gradually turns from red to pink to brown (rare to medium to well-done) when heated.

Prosciutto hams also get their pink color from salt combined with the natural protein called myoglobin.

The shells and flesh of steamed shrimp contain a natural carotenoid pigment called astaxanthin, which turns pink when heated. The same process turns cooked lobster and crab from blue-green to red when they are boiled.

The meat of the salmon is also colored pink by the natural carotenoid pigment called astaxanthin.

Plants and flowers
Pink is one of the most common colors of flowers; it serves to attract the insects and birds necessary for pollination and perhaps also to deter predators. The color comes from natural pigments called anthocyanins, which also provide the pink in raspberries.

A pink rose picture

Pigments - Pinke

In the 17th century, the word pink or pinke was also used to describe a yellowish pigment, which was mixed with blue colors to yield greenish colors. Thomas Jenner's A Book of Drawing, Limning, Washing (1652) categorizes "Pink & blew bice" amongst the greens (p.  38), and specifies several admixtures of greenish colors made with pink—e.g. "Grasse-green is made of Pink and Bice, it is shadowed with Indigo and Pink … French-green of Pink and Indico [shadowed with] Indico" (pp. 38–40). In William Salmon's Polygraphice (1673), "Pink yellow" is mentioned amongst the chief yellow pigments (p. 96), and the reader is instructed to mix it with either Saffron or Ceruse for "sad" or "light" shades thereof, respectively.

Sonics
Pink noise (About this sound sample (help•info)), also known as 1/f noise, in audio engineering is a signal or process with a frequency spectrum such that the power spectral density is proportional to the reciprocal of the frequency.

Lighting
Grow lights often use a combination of red and blue wavelengths, which generally appear pink to the human eye.

Pink neon signs are generally produced using one of two different methods. One method is to use neon gas and a blue or purple phosphor, which generally produces a warmer (more reddish) or more intense shade of pink. Another method is to use an argon/mercury blend and a red phosphor, which generally produces a cooler (more purplish) or softer shade of pink.

Pink LEDs can be produced using two methods, either with a blue LED using two phosphors (yellow for the first phosphor, and red, orange, or pink for the second), or by placing a pink dye on top of a white LED. Color shifting was a common issue with early pink LEDs, where the red, orange, or pink phosphors or dyes faded over time, causing the pink color to eventually shift towards white or blue. These issues have been mitigated by the more recent introduction of more fade-resistant phosphors.

Engineering
Insulation manufactured by Owens Corning is dyed pink, with the Pink Panther as its corporate mascot. The company holds a trademark on the color pink for insulation products in order to prevent competitors from using it, and is the first company in the United States to trademark a color.

The United States Manual on Uniform Traffic Control Devices specifies fluorescent pink as an optional color for traffic signs used for incident management as an alternative to the traditional orange in order to distinguish them from construction zone signs.

Source From Wikipedia

Pink color in history and art

Pink is a pale red color that is named after a flower of the same name. It was first used as a color name in the late 17th century. According to surveys in Europe and the United States, pink is the color most often associated with charm, politeness, sensitivity, tenderness, sweetness, childhood, femininity and the romantic. It is associated with chastity and innocence when combined with white, but associated with eroticism and seduction when combined with purple or black.

History, art and fashion

From prehistory to post-classical history
The color pink has been described in literature since ancient times. In the Odyssey, written in approximately 800 BCE, Homer wrote "Then, when the child of morning, rosy-fingered dawn appeared..." Roman poets also described the color. Roseus is the Latin word meaning "rosy" or "pink." Lucretius used the word to describe the dawn in his epic poem On the Nature of Things (De rerum natura).

Pink was not a common color in the fashion of the Middle Ages; nobles usually preferred brighter reds, such as crimson. However, it did appear in women's fashion, and in religious art. In the 13th and 14th century, in works by Cimabue and Duccio, the Christ child was sometimes portrayed dressed in pink, the color associated with the body of Christ.

In the high Renaissance painting the Madonna of the Pinks by Raphael, the Christ child is presenting a pink flower to the Virgin Mary. The pink was a symbol of marriage, showing a spiritual marriage between the mother and child.

Modern history
Early modern
During the Renaissance, pink was mainly used for the flesh color of faces and hands. The pigment commonly used for this was called light cinabrese; it was a mixture of the red earth pigment called sinopia, or Venetian red, and a white pigment called Bianco San Genovese, or lime white. In his famous 15th century manual on painting, Il Libro Dell'Arte, Cennino Cennini described it this way: "This pigment is made from the loveliest and lightest sinopia that is found and is mixed and mulled with St. John’s white, as it is called in Florence; and this white is made from thoroughly white and thoroughly purified lime. And when these two pigments have been thoroughly mulled together (that is, two parts cinabrese and the third white), make little loaves of them like half walnuts and leave them to dry. When you need some, take however much of it seems appropriate. And this pigment does you great credit if you use it for painting faces, hands and nudes on walls..."

Late modern
The 18th century
The golden age of the color pink was the Rococo Period (1720–1777) in the 18th century, when pastel colors became very fashionable in all the courts of Europe. Pink was particularly championed by Madame de Pompadour (1721–1764), the mistress of King Louis XV of France, who wore combinations of pale blue and pink, and had a particular tint of pink made for her by the Sevres porcelain factory, created by adding nuances of blue, black and yellow.

While pink was quite evidently the color of seduction in the portraits made by George Romney of Emma, Lady Hamilton, the future mistress of Admiral Horatio Nelson, in the late 18th century, it had the completely opposite meaning in the portrait of Sarah Barrett Moulton painted by Thomas Lawrence in 1794. In this painting, it symbolized childhood, innocence and tenderness. Sarah Moulton was just eleven years old when the picture was painted, and died the following year.

The 19th century
In 19th century England, pink ribbons or decorations were often worn by young boys; boys were simply considered small men, and while men in England wore red uniforms, boys wore pink. In fact the clothing for children in the 19th century was almost always white, since, before the invention of chemical dyes, clothing of any color would quickly fade when washed in boiling water. Queen Victoria was painted in 1850 with her seventh child and third son, Prince Arthur, who wore white and pink.

The 20th century
In the 20th century, pinks became bolder, brighter, and more assertive, in part because of the invention of chemical dyes which did not fade. The pioneer in the creation of the new wave of pinks was the Italian designer Elsa Schiaparelli, (1890-1973) who was aligned with the artists of the surrealist movement, including Jean Cocteau. In 1931 she created a new variety of the color, called shocking pink, made by mixing magenta with a small amount of white. She launched a perfume called Shocking, sold in a bottle in the shape of a woman's torso, said to be modelled on that of Mae West. Her fashions, co-designed with artists such as Cocteau, featured the new pinks.

In Nazi Germany in the 1930s and 1940s, inmates of Nazi concentration camps who were accused of homosexuality were forced to wear a pink triangle. Because of this, the pink triangle has become a symbol of the modern gay rights movement.

The transition to pink as a sexually differentiating color for girls occurred gradually, through the selective process of the marketplace, in the 1930s and 40s. In the 1920s, some groups had been describing pink as a masculine color, an equivalent of the red that was considered to be for men, but lighter for boys. But stores nonetheless found that people were increasingly choosing to buy pink for girls, and blue for boys, until this became an accepted norm in the 1940s.

The US presidential inauguration of Dwight D. Eisenhower in 1953 when Eisenhower's wife Mamie Eisenhower wore a pink dress as her inaugural gown is thought to have been a key turning point to the association of pink as a color associated with girls. Mamie's strong liking of pink led to the public association with pink being a color that "ladylike women wear." The 1957 American musical Funny Face also played a role in cementing the color's association with women.

In 1973, Sheila Levrant de Bretteville created "Pink," a broadside (poster) meant to explore the notions of gender as associated with the color pink, for an American Institute of Graphic Arts exhibition about color. This was the only entry about the color pink. Various women including many in the Feminist Studio Workshop at the Woman's Building submitted entries exploring their association with the color. De Bretteville arranged the squares of paper to form a "quilt" from which posters were printed and disseminated throughout Los Angeles. She was often called "Pinky" as a result.

Christo and Jeanne-Claude's Surrounded Islands wrapped wooded islands in Miami's Biscayne Bay with 6,500,000 sq ft (600,000 m2) of bright pink fabric. Thomas von Taschitzki has said that "the monochrome pink wrappings"..."form a counterpoint to the small green wooded islands."

Many of Franz West's aluminium sculptures were often painted a bright pink, for example Sexualitätssymbol (Symbol of Sexuality). West has said that the pink was intended as an "outcry to nature".

Source From Wikipedia

Yellow color in culture

Yellow is the color between green and orange on the spectrum of visible light. It is evoked by light with a dominant wavelength of roughly 570–590 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the RGB color model, used to create colors on television and computer screens, yellow is a secondary color made by combining red and green at equal intensity. Carotenoids give the characteristic yellow color to autumn leaves, corn, canaries, daffodils, and lemons, as well as egg yolks, buttercups, and bananas. They absorb light energy and protect plants from photodamage. Sunlight has a slight yellowish hue, due to the surface temperature of the sun.

Because it was widely available, yellow ochre pigment was one of the first colors used in art; the Lascaux cave in France has a painting of a yellow horse 17,000 years old. Ochre and orpiment pigments were used to represent gold and skin color in Egyptian tombs, then in the murals in Roman villas. In the early Christian church, yellow was the color associated with the Pope and the golden keys of the Kingdom, but was also associated with Judas Iscariot and was used to mark heretics. In the 20th century, Jews in Nazi-occupied Europe were forced to wear a yellow star. In China, yellow was the color of the Middle Kingdom, and could be worn only by the Emperor and his household; special guests were welcomed on a yellow carpet.

According to surveys in Europe, Canada, and the United States, yellow is the color people most often associate with amusement, gentleness, humor, and spontaneity, but also with duplicity, envy, jealousy, avarice, and, in the U.S., with cowardice. In Iran it has connotations of pallor/sickness, but also wisdom and connection. In China and many Asian countries, it is seen as the color of happiness, glory, harmony and wisdom.

Symbolism and associations
In the west, yellow is not a well-loved color; in a 2000 survey, only six percent of respondents in Europe and America named it as their favorite color. compared with 45 percent for blue, 15 percent for green, 12 percent for red, and 10 percent for black. For seven percent of respondents, it was their least favorite color. Yellow is the color of ambivalence and contradiction; the color associated with optimism and amusement; but also with betrayal, duplicity, and jealousy. But in China and other parts of Asia, yellow is a color of virtue and nobility.

In China
Yellow has strong historical and cultural associations in China, where it is the color of happiness, glory, and wisdom. In China, there are five directions of the compass; north, south, east, west, and the middle, each with a symbolic color. Yellow signifies the middle. China is called the Middle Kingdom; the palace of the Emperor was considered to be in the exact center of the world.

The legendary first emperor of China was called the Yellow Emperor. The last emperor of China, Puyi (1906–67), described in his memoirs how every object which surrounded him as a child was yellow. "It made me understand from my most tender age that I was of a unique essence, and it instilled in me the consciousness of my 'celestial nature' which made me different from every other human."

The Chinese Emperor was literally considered the child of heaven, with both a political and religious role, both symbolized by yellow. Only members of the Imperial household were permitted to wear yellow. Distinguished visitors were honored with a yellow, not a red, carpet.

In Chinese symbolism, yellow, red and green are masculine colors, while black and white are considered feminine. In the traditional symbolism of the two opposites which complement each other, the yin and yang, the masculine yang is traditionally represented by yellow. Just as there are five elements, five directions and five colors in the Chinese world-view, there are also five seasons; summer, winter, fall, spring, and the end of summer, symbolized by yellow leaves.

Light and reason
Yellow, as the color of sunlight, is commonly associated with warmth. Yellow combined with red symbolized heat and energy. A room painted yellow feels warmer than a room painted white, and a lamp with yellow light seems more natural than a lamp with white light.

As the color of light, yellow is also associated with knowledge and wisdom. In English and many other languages, "brilliant" and "bright" mean intelligent. In Islam, the yellow color of gold symbolizes wisdom. In medieval European symbolism, red symbolized passion, blue symbolized the spiritual, and yellow symbolized reason. In many European universities, yellow gowns and caps are worn by members of the faculty of physical and natural sciences, as yellow is the color of reason and research.

Gold and blond
In ancient Greece and Rome, the gods were often depicted with yellow, or blonde hair; which was described in literature as 'golden'. The color yellow was associated with the sun gods Helios and Apollo. It was fashionable in ancient Greece for men and women to dye their hair yellow, or to spend time in the sun to bleach it. In ancient Rome, prostitutes were required to bleach their hair, to be easily identified, but it also became a fashionable hair color for aristocratic women, influenced by the exotic blonde hair of many of the newly conquered slaves from Gaul, Britain, and Germany. However, in medieval Europe and later, the word yellow often had negative connotations; associated with betrayal, so yellow hair was more poetically called 'blond,' 'light', 'fair,' or most often "golden".

Visibility and caution
Yellow is the most visible color from a distance, so it is often used for objects that need to be seen, such as fire engines, road maintenance equipment, school buses and taxicabs. It is also often used for warning signs, since yellow traditionally signals caution, rather than danger. Safety yellow is often used for safety and accident prevention information. A yellow light on a traffic signal means slow down, but not stop. The Occupational Safety and Health Administration (OSHA) uses Pantone 116 (a yellow hue) as their standard color implying "general warning," while the Federal Highway Administration similarly uses yellow to communicate warning or caution on highway signage. A yellow penalty card in a soccer match means warning, but not expulsion.

Optimism and pleasure
Yellow is the color most associated with optimism and pleasure; it is a color designed to attract attention, and is used for amusement. Yellow dresses in fashion are rare, but always associated with gaiety and celebration.

In other cultures
The ancient Maya associated the color yellow with the direction South. The Maya glyph for "yellow" (k'an) also means "precious" or "ripe".
Yellow" ("giallo"), in Italy, refers to crime stories, both fictional and real. This association began in about 1930, when the first series of crime novels published in Italy had yellow covers.
Music
The Beatles 1966 album Revolver features the No. 1 hit, "Yellow Submarine". Subsequently, United Artists released an animated film in 1968 called Yellow Submarine, based on the music of the Beatles.
The March 1967 album by Donovan called Mellow Yellow reached number 2 on the U.S. Billboard charts in 1966 and number 8 in the UK in early 1967. The featured song on the album, "Mellow Yellow", popularized during the Spring of 1967 a widely believed hoax that it was possible to get high by smoking scrapings from the inside of banana peels, although this rumor was actually started in 1966 by Country Joe McDonald.
Coldplay achieved worldwide fame with their 2000 single "Yellow".
"Yellow River" is a song recorded by the British band Christie in 1970.
The "Yellow River Piano Concerto" is a piano concerto arranged by a collaboration between musicians including Yin Chengzong and Chu Wanghua. Its premiere was in 1969 during the Cultural Revolution.

Politics
In the United States, a yellow dog Democrat was a Southern voter who consistently voted for Democratic candidates in the late 19th and early 20th centuries because of lingering resentment against the Republicans dating back to the Civil War and Reconstruction period. Today the term refers to a hard-core Democrat, supposedly referring to a person who would vote for a "yellow dog" before voting for a Republican.
In China the Yellow Turbans were a Daoist sect that staged an extensive rebellion during the Han Dynasty.
Yellow is an important color of anarcho-capitalist symbolism.
The 1986 People Power Revolution in the Philippines was also known as the Yellow Revolution due to the presence of yellow ribbons during the demonstrations.
Contemporary political parties using yellow include the Liberal Democrats and UKIP in the UK, SNP in Scotland and Libertarian Party in the US.

Historic flags
The banner of the Holy Roman Empire (15th century). The black, yellow and red colors reappeared first in 1848 and then in the 20th century in the German flag.

(1819) The flag of Gran Colombia, which won independence from Spain, then broke into three countries (Colombia, Venezuela and Ecuador) in 1830.

Imperial flag of the Qing Dynasty, China (1890–1912), the last dynasty of China, overthrown by the Xinhai Revolution of 1911.

Flag of South Vietnam (1955–75). This was the flag of the anti-communist southern part of Vietnam during the Vietnam War. It was replaced by the flag of North Vietnam after communist forces took Saigon on April 30, 1975.

The flag of East Germany (1959–90). It differs from the West German flag by the presence of a communist symbol in the center, and it fell out of use when Germany was reunified after the fall of the Berlin Wall.

Selected national and international flags
Three of the five most populous countries in the world (China, India, and Brazil) have yellow or gold in their flag, representing about half of the world's population. While many flags use yellow, their symbolism varies widely, from civic virtue to golden treasure, golden fields, the desert, royalty, the keys to Heaven and the leadership of the Communist Party. In classic European heraldry, yellow, along with white, is one of the two metals (called gold and silver) and therefore flags following heraldic design rules must use either yellow or white to separate any of their other colors (see rule of tincture).

Flag of India (1947). The yellow color is officially called India saffron, and represents courage and sacrifice.

Flag of Germany. Black, red and yellow were the colors of the Holy Roman Emperor, and, in 1919, of the German Weimar Republic. The modern German flag was adopted in 1949.

Flag of Ukraine (1992 (originally in 1918)).

Flag of Belgium (1831). The yellow comes from the yellow lion in the coat of arms of the Duchy of Brabant, founded in 1183–84.

Flag of Bhutan (1956). The Bhutan flag features Druk, the thunder dragon of Bhutanese mythology. The yellow represents civic tradition, the red the Buddhist spiritual tradition.

Flag of the People's Republic of China (1949). The four small gold stars represent the workers, peasants, urban middle class, and rural middle class. The large star represents the Chinese Communist Party.

Flag of Brazil (1889). The yellow color was inherited from the flag of the Empire of Brazil (1822–1889), where it represented the color of the House of Habsburg.

Flag of Brunei (1956). In Southeast Asia yellow is the color of royalty. it is the color of the Sultan of Brunei, and also appears on the flag of Thailand and of Malaysia.

Flag of Colombia. The asymmetric design of the flag is based on the old Flag of Gran Colombia. The yellow color represents the golden treasure taken from Colombia over the centuries.

Flag of Spain (1978). The yellow in the Spanish flag comes from the traditional Crown of Castille and the Crown of Aragon. The general design was adopted in 1785 for the Spanish Navy, to be visible from a great distance at sea.

Flag of Lithuania (1918 to 1940, restored in 1989, modified in 2004). Yellow represents the golden fields of Lithuania, green the countryside, and red the blood of Lithuanian martyrs.

Flag of Malaysia (original version, 1950, current version 1963.) The yellow crescent represents Islam, the yellow star the unity of the fourteen states of Malaysia. The red and white stripes (like the stripes on the U.S. flag) are adopted from the flag of the British East India Company.

Flag of Mozambique (1983). The colors are those of the Marxist Liberation Front of Mozambique, or FRELIMO, which rules the country. Yellow represents the country's mineral wealth.

Flag of Romania (1848, and again in 1989, after the fall of the Communist regime.) Blue, yellow and red were the colors of the Wallachian uprising of 1821, and the 1848 revolution which won independence for Romania. Yellow represents justice.

Flag of Sweden (adopted 1906, but colors in use since at least the mid-16th century). The legend says that in 1157, during the First Swedish Crusade, the Swedish king Eric the Holy saw a golden cross appear in the blue sky.

Flag of Chad (1959). The color yellow here represents the sun and the desert in the north of the country. This flag is identical to that of Romania, except that it uses a slightly darker indigo blue rather than cobalt blue.

Flag of the European Union. The flag of the European Union was first created for the Council of Europe in 1953, then adopted by the European Union in 1985. The twelve yellow or gold stars do not represent any particular countries; twelve was chosen as a number which represented unity and harmony.

Flag of Vatican City (1929). The yellow color represents the golden key of the Kingdom of heaven, described in the Book of Matthew of the New Testament, and part of the Papal seal on the flag.

Religion
in The Roman Catholic church, yellow symbolizes gold, and the golden key to the Kingdom of Heaven, which Christ gave to Saint Peter. The flag of the Vatican City and the colors of the pope are yellow and white, symbolizing the gold key and the silver key. White and yellow together can also symbolize easter, rebirth and Resurrection. Golden haloes mark the saints in religious paintings. Yellow also has a negative meaning, symbolizing betrayal; Judas Iscariot is usually portrayed wearing a pale yellow toga, and without a halo.
In Hinduism, the divinity Krishna is commonly portrayed dressed in yellow. Yellow and saffron are also the colors worn by sadhu, or wandering holy men in India. The Hindu almighty and divine god Lord Ganesha or Ganpati is mostly dressed with a dhotar in yellow, which is popularly known as pivla pitambar and is considered to be the most auspicious one.
In Buddhism, the saffron colors of robes to be worn by monks were defined by the Buddha himself and his followers in the 5th century BC. The robe and its color is a sign of renunciation of the outside world and commitment to the order. The candidate monk, with his master, first appears before the monks of the monastery in his own clothes, with his new robe under his arm, and asks to enter the order. He then takes his vows, puts on the robes, and with his begging bowl, goes out to the world. Thereafter, he spends his mornings begging and his afternoons in contemplation and study, either in a forest, garden, or in the monastery.
According to Buddhist scriptures and commentaries, the robe dye is allowed to be obtained from six kinds of substances: roots and tubers, plants, bark, leaves, flowers and fruits. The robes should also be boiled in water a long time to get the correctly sober color. Saffron and ochre, usually made with dye from the curcuma longa plant or the heartwood of the jackfruit tree, are the most common colors. The so-called forest monks usually wear ochre robes and city monks saffron, though this is not an official rule.

The color of robes also varies somewhat among the different "vehicles", or schools of Buddhism, and by country, depending on their doctrines and the dyes available. The monks of the strict Vajrayana, or Tantric Buddhism, practiced in Tibet, wear the most colorful robes of saffron and red. The monks of Mahayana Buddhism, practiced mainly in Japan, China and Korea, wear lighter yellow or saffron, often with white or black. Monks of Hinayana Buddhism, practiced in Southeast Asia, usually wear ochre or saffron color. Monks of the forest tradition in Thailand and other parts of Southeast Asia wear robes of a brownish ochre, dyed from the wood of the jackfruit tree.

In the religions of the islands of Polynesia, yellow is a sacred color, the color of the divine essence; the word "yellow" in the local languages is the same as the name of the curcuma longa plant, which is considered the food of the gods.

Metaphysics
In the metaphysics of the New Age Prophetess, Alice A. Bailey, in her system called the Seven Rays which classifies humans into seven different metaphysical psychological types, the fourth ray of harmony through conflict is represented by the color yellow. People who have this metaphysical psychological type are said to be on the Yellow Ray."
Yellow is used to symbolically represent the third, solar plexus chakra (Manipura).
Psychics who claim to be able to observe the aura with their third eye report that someone with a yellow aura is typically someone who is in an occupation requiring intellectual acumen, such as a scientist.

Sports
In Association football (soccer), the referee shows a yellow card to indicate that a player has been officially warned because they have committed a foul or have wasted time.
Originally in Rugby League and then later, also in Rugby Union, the referee shows a yellow card to indicate that a player has been sent to the sin bin.
In cycle racing, the yellow jersey – or maillot jaune – is awarded to the leader in some stage races. The tradition was begun in the Tour de France where the sponsoring L'Auto newspaper (later L'Équipe) was printed on distinctive yellow newsprint.

Transportation
In some countries, taxicabs are commonly yellow. This practice began in Chicago, where taxi entrepreneur John D. Hertz painted his taxis yellow based on a University of Chicago study alleging that yellow is the color most easily seen at a distance.
In Canada and the United States, school buses are almost uniformly painted a yellow color (often referred to as "school bus yellow") for purposes of visibility and safety, and British bus operators such as FirstGroup are attempting to introduce the concept there.
"Caterpillar yellow" and "high-visibility yellow" are used for highway construction equipment.
In the rules of the road, yellow (called "amber" in Britain) is a traffic light signal meaning "slow down", "caution", or "slow speed ahead". It is intermediate between green (go) and red (stop). In railway signaling, yellow is often the color for warning, slow down, such as with distant signals.
Selective yellow is used in some automotive headlamps and fog lights to reduce the dazzling effects of rain, snow, and fog.

Vexillology
In International maritime signal flags a yellow flag denotes the letter "Q". It also means a ship asserts that it does not need to be quarantined.

Idioms and expressions
Yellow-belly is an American expression which means a coward. The term comes from the 19th century and the exact origin is unknown, but it may refer to the color of sickness, which means a person lacks strength and stamina.
Yellow pages refers in various countries to directories of telephone numbers, arranged alphabetically by the type of business or service offered.
The Yellow Peril was a term used in politics and popular fiction in the late 19th and early 20th century to describe the alleged economic and cultural danger posed to Europe and America by Chinese immigration. The term was first used by Kaiser Wilhelm II in Germany in 1895, and was the subject of numerous books and later films.
High yellow was a term sometimes used in the early 20th century, to describe light-skinned African-Americans.

Source From Wikipedia

Yellow color in history and art

Yellow is the color between green and orange on the spectrum of visible light. It is evoked by light with a dominant wavelength of roughly 570–590 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the RGB color model, used to create colors on television and computer screens, yellow is a secondary color made by combining red and green at equal intensity. Carotenoids give the characteristic yellow color to autumn leaves, corn, canaries, daffodils, and lemons, as well as egg yolks, buttercups, and bananas. They absorb light energy and protect plants from photodamage. Sunlight has a slight yellowish hue, due to the surface temperature of the sun.

Because it was widely available, yellow ochre pigment was one of the first colors used in art; the Lascaux cave in France has a painting of a yellow horse 17,000 years old. Ochre and orpiment pigments were used to represent gold and skin color in Egyptian tombs, then in the murals in Roman villas. In the early Christian church, yellow was the color associated with the Pope and the golden keys of the Kingdom, but was also associated with Judas Iscariot and was used to mark heretics. In the 20th century, Jews in Nazi-occupied Europe were forced to wear a yellow star. In China, yellow was the color of the Middle Kingdom, and could be worn only by the Emperor and his household; special guests were welcomed on a yellow carpet.

According to surveys in Europe, Canada, and the United States, yellow is the color people most often associate with amusement, gentleness, humor, and spontaneity, but also with duplicity, envy, jealousy, avarice, and, in the U.S., with cowardice. In Iran it has connotations of pallor/sickness, but also wisdom and connection. In China and many Asian countries, it is seen as the color of happiness, glory, harmony and wisdom.

History, art, and fashion

Prehistory
Yellow, in the form of yellow ochre pigment made from clay, was one of the first colors used in prehistoric cave art. The cave of Lascaux has an image of a horse colored with yellow estimated to be 17,300 years old.

Ancient history
In Ancient Egypt, yellow was associated with gold, which was considered to be imperishable, eternal and indestructible. The skin and bones of the gods were believed to be made of gold. The Egyptians used yellow extensively in tomb paintings; they usually used either yellow ochre or the brilliant orpiment, though it was made of arsenic and was highly toxic. A small paintbox with orpiment pigment was found in the tomb of King Tutankhamun. Men were always shown with brown faces, women with yellow ochre or gold faces.

The ancient Romans used yellow in their paintings to represent gold and also in skin tones. It is found frequently in the murals of Pompeii.

Post-classical history
During the Post-Classical period, yellow became firmly established as the color of Judas Iscariot, the disciple who betrayed Jesus Christ, even though the Bible never describes his clothing. From this connection, yellow also took on associations with envy, jealousy and duplicity.

The tradition started in the Renaissance of marking non-Christian outsiders, such as Jews, with the color yellow. In 16th century Spain, those accused of heresy and who refused to renounce their views were compelled to come before the Spanish Inquisition dressed in a yellow cape.

The color yellow has been historically associated with moneylenders and finance. The National Pawnbrokers Association's logo depicts three golden spheres hanging from a bar, referencing the three bags of gold that the patron saint of pawnbroking, St. Nicholas, holds in his hands. Additionally, the symbol of three golden orbs is found in the coat of arms of the House of Medici, a famous fifteenth century Italian dynasty of bankers and lenders.

Modern history

18th and 19th centuries
The 18th and 19th century saw the discovery and manufacture of synthetic pigments and dyes, which quickly replaced the traditional yellows made from arsenic, cow urine, and other substances.

Circa 1776, Jean-Honoré Fragonard painted A Young Girl Reading. She is dressed in a bright saffron yellow dress. This painting is "considered by many critics to be among Fragonard's most appealing and masterly".

The 19th-century British painter J.M.W. Turner was one of the first in that century to use yellow to create moods and emotions, the way romantic composers were using music. His painting Rain, Steam, and Speed – the Great Central Railway was dominated by glowing yellow clouds.

Georges Seurat used the new synthetic colors in his experimental paintings composed of tiny points of primary colors, particularly in his famous Sunday Afternoon on the Isle de la Grand jatte (1884–86). He did not know that the new synthetic yellow pigment, zinc yellow or zinc chromate, which he used in the light green lawns, was highly unstable and would quickly turn brown.

The painter Vincent van Gogh was a particular admirer of the color yellow, the color of sunshine. Writing to his sister from the south of France in 1888, he wrote, "Now we are having beautiful warm, windless weather that is very beneficial to me. The sun, a light that for lack of a better word I can only call yellow, bright sulfur yellow, pale lemon gold. How beautiful yellow is!" In Arles, Van Gogh painted sunflowers inside a small house he rented at 2 Place Lamartine, a house painted with a color that Van Gogh described as "buttery yellow." Van Gogh was one of the first artists to use commercially manufactured paints, rather than paints he made himself. He used the traditional yellow ochre, but also chrome yellow, first made in 1809, and cadmium yellow, first made in 1820.

At the end of the 19th century, in 1895, a new popular art form began to appear in New York newspapers; the color comic strip. It took advantage of a new color printing process, which used color separation and three different colors of ink; magenta, cyan, and yellow, plus black, to create all the colors on the page. One of the first characters in the new comic strips was a humorous boy of the New York streets named Mickey Dugen, more commonly known as the Yellow Kid, from the yellow nightshirt he wore. He gave his name (and color) to the whole genre of popular, sensational journalism, which became known as "yellow journalism".

20th and 21st centuries
In the 20th century, yellow was revived as a symbol of exclusion, as it had been in the Middle Ages and Renaissance. Jews in Nazi Germany and German-occupied countries were required to sew yellow triangles with the star of David onto their clothing.

In the 20th century, modernist painters reduced painting to its simplest colors and geometric shapes. The Dutch modernist painter Piet Mondrian made a series of paintings which consisted of a pure white canvas with a grid of vertical and horizontal black lines and rectangles of yellow, red, and blue.

Yellow was particularly valued in the 20th century because of its high visibility. Because of its ability to be seen well from greater distances and at high speeds, yellow makes for the ideal color to be viewed from moving automobiles. It often replaced red as the color of fire trucks and other emergency vehicles, and was popular in neon signs, especially in Las Vegas and in China, where yellow was the most esteemed color.

In the 1960s, Pickett Brand developed the "Eye Saver Yellow" slide rule, which was produced with a specific yellow color (Angstrom 5600) that reflects long-wavelength rays and promotes optimum eye-ease to help prevent eyestrain and improve visual accuracy.

The 21st century saw the use of unusual materials and technologies to create new ways of experiencing the color yellow. One example was The weather project, by Danish-Icelandic artist Olafur Eliasson, which was installed in the open space of the Turbine Hall of London's Tate Modern in 2003.

Eliasson used humidifiers to create a fine mist in the air via a mixture of sugar and water, as well as a semi-circular disc made up of hundreds of monochromatic lamps which radiated yellow light. The ceiling of the hall was covered with a huge mirror, in which visitors could see themselves as tiny black shadows against a mass of light.

Source From Wikipedia

Yellow color in science and nature


Yellow is the color between green and orange on the spectrum of visible light. It is evoked by light with a dominant wavelength of roughly 570–590 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the RGB color model, used to create colors on television and computer screens, yellow is a secondary color made by combining red and green at equal intensity. Carotenoids give the characteristic yellow color to autumn leaves, corn, canaries, daffodils, and lemons, as well as egg yolks, buttercups, and bananas. They absorb light energy and protect plants from photodamage. Sunlight has a slight yellowish hue, due to the surface temperature of the sun.

Because it was widely available, yellow ochre pigment was one of the first colors used in art; the Lascaux cave in France has a painting of a yellow horse 17,000 years old. Ochre and orpiment pigments were used to represent gold and skin color in Egyptian tombs, then in the murals in Roman villas. In the early Christian church, yellow was the color associated with the Pope and the golden keys of the Kingdom, but was also associated with Judas Iscariot and was used to mark heretics. In the 20th century, Jews in Nazi-occupied Europe were forced to wear a yellow star. In China, yellow was the color of the Middle Kingdom, and could be worn only by the Emperor and his household; special guests were welcomed on a yellow carpet.

According to surveys in Europe, Canada, and the United States, yellow is the color people most often associate with amusement, gentleness, humor, and spontaneity, but also with duplicity, envy, jealousy, avarice, and, in the U.S., with cowardice. In Iran it has connotations of pallor/sickness, but also wisdom and connection. In China and many Asian countries, it is seen as the color of happiness, glory, harmony and wisdom.

Etymology
The word yellow comes from the Old English geolu, geolwe (oblique case), meaning "yellow, yellowish", derived from the Proto-Germanic word gelwaz "yellow". It has the same Indo-European base, gʰel-, as the words gold and yell; gʰel- means both bright and gleaming, and to cry out.

The English term is related to other Germanic words for yellow, namely Scots yella, East Frisian jeel, West Frisian giel, Dutch geel, German gelb, and Swedish and Norwegian gul. According to the Oxford English Dictionary, the oldest known use of this word in English is from The Epinal Glossary in 700.

Science and nature
Optics, color printing, and computer screens
Yellow is found between green and orange on the spectrum of visible light. It is the color the human eye sees when it looks at light with a dominant wavelength between 570 and 590 nanometers.

In color printing, yellow is one of the three colors of ink, along with magenta and cyan, which, along with black, can be overlaid in the right combination, along with black, to print any full color image. (See the CMYK color model). A particular yellow is used, called Process yellow (also known as "pigment yellow", "printer's yellow", and "canary yellow") subtractive primary colors, along with magenta and cyan. Process yellow is not an RGB color, and there is no fixed conversion from CMYK primaries to RGB. Different formulations are used for printer's ink, so there can be variations in the printed color that is pure yellow ink.

The yellow on a color television or computer screen is created in a completely different way; by combining green and red light at the right level of intensity. (See RGB color model).

Complementary colors

Traditionally, the complementary color of yellow is purple; the two colors are opposite each other on the color wheel long used by painters. Vincent Van Gogh, an avid student of color theory, used combinations of yellow and purple in several of his paintings for the maximum contrast and harmony.

Hunt defines that "two colors are complementary when it is possible to reproduce the tristimulus values of a specified achromatic stimulus by an additive mixture of these two stimuli." That is, when two colored lights can be mixed to match a specified white (achromatic, non-colored) light, the colors of those two lights are complementary. This definition, however, does not constrain what version of white will be specified. In the nineteenth century, the scientists Grassmann and Helmholtz did experiments in which they concluded that finding a good complement for spectral yellow was difficult, but that the result was indigo, that is, a wavelength that today's color scientists would call violet or purple. Helmholtz says "Yellow and indigo blue" are complements. Grassmann reconstructs Newton's category boundaries in terms of wavelengths and says "This indigo therefore falls within the limits of color between which, according to Helmholtz, the complementary colors of yellow lie."

Newton's own color circle has yellow directly opposite the boundary between indigo and violet. These results, that the complement of yellow is a wavelength shorter than 450 nm, are derivable from the modern CIE 1931 system of colorimetry if it is assumed that the yellow is about 580 nm or shorter wavelength, and the specified white is the color of a blackbody radiator of temperature 2800 K or lower (that is, the white of an ordinary incandescent light bulb). More typically, with a daylight-colored or around 5000 to 6000 K white, the complement of yellow will be in the blue wavelength range, which is the standard modern answer for the complement of yellow.

Because of the characteristics of paint pigments and use of different color wheels, painters traditionally regard the complement of yellow as the color indigo or blue-violet.

Lasers
Lasers emitting in the yellow part of the spectrum are less common and more expensive than most other colors. In commercial products diode pumped solid state (DPSS) technology is employed to create the yellow light. An infrared laser diode at 808 nm is used to pump a crystal of neodymium-doped yttrium vanadium oxide (Nd:YVO4) or neodymium-doped yttrium aluminium garnet (Nd:YAG) and induces it to emit at two frequencies (281.76 THz and 223.39 THz: 1064 nm and 1342 nm wavelengths) simultaneously. This deeper infrared light is then passed through another crystal containing potassium, titanium and phosphorus (KTP), whose non-linear properties generate light at a frequency that is the sum of the two incident beams (505.15 THz); in this case corresponding to the wavelength of 593.5 nm ("yellow"). This wavelength is also available, though even more rarely, from a helium–neon laser. However, this not a true yellow, as it exceeds 590 nm. A variant of this same DPSS technology using slightly different starting frequencies was made available in 2010, producing a wavelength of 589 nm, which is considered a true yellow color. The use of yellow lasers at 589 nm and 594 nm have recently become more widespread thanks to the field of optogenetics.

Astronomy
Stars of spectral classes F and G, such as our Sun, have color temperatures that make them look "yellowish". The first astronomer to classify stars according to their color was F. G. W. Struve in 1827. One of his classifications was flavae, or yellow, and this roughly corresponded to stars in the modern spectral range F5 to K0. The Strömgren photometric system for stellar classification includes a 'y' or yellow filter that is centered at a wavelength of 550 nm and has a bandwidth of 20–30 nm.

Biology
Autumn leaves, yellow flowers, bananas, oranges and other yellow fruits all contain carotenoids, yellow and red organic pigments that are found in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria and some fungi. They serve two key roles in plants and algae: they absorb light energy for use in photosynthesis, and they protect the green chlorophyll from photodamage.

In late summer, as daylight hours shorten and temperatures cool, the veins that carry fluids into and out of the leaf are gradually closed off. The water and mineral intake into the leaf is reduced, slowly at first, and then more rapidly. It is during this time that the chlorophyll begins to decrease. As the chlorophyll diminishes, the yellow and red carotenoids become more and more visible, creating the classic autumn leaf color.

Carotenoids are common in many living things; they give the characteristic color to carrots, corn, daffodils, rutabagas, buttercups and bananas. They are responsible for the red of cooked lobsters, the pink of flamingoes and salmon and the yellow of canaries and egg yolks.

Xanthophylls are the most common yellow pigments that form one of two major divisions of the carotenoid group. The name is from Greek xanthos (ξανθος, "yellow") + phyllon (φύλλον, "leaf"). Xanthophylls are most commonly found in the leaves of green plants, but they also find their way into animals through the food they eat. For example, the yellow color of chicken egg yolks, fat, and skin comes from the feed the chickens consume. Chicken farmers understand this, and often add xanthophylls, usually lutein, to make the egg yolks more yellow.

Bananas are green when they are picked because of the chlorophyll their skin contains. Once picked, they begin to ripen; hormones in the bananas convert amino acids into ethylene gas, which stimulates the production of several enzymes. These enzymes start to change the color, texture and flavor of the banana. The green chlorophyll supply is stopped and the yellow color of the carotenoids replaces it; eventually, as the enzymes continue their work, the cell walls break down and the bananas turn brown.

Fish
Yellowtail is the common name for dozens of different fish species that have yellow tails or a yellow body.
Yellowfin tuna (Thunnus albacares) is a species of tuna, having bright yellow anal and second dorsal fins. Found in tropical and subtropical seas and weighing up to 200 kg (440 lb), it is caught as a replacement for depleted stocks of bluefin tuna.
Insects

The yellow-fever mosquito (Aedes aegypti) is a mosquito so named because it transmits dengue fever and yellow fever, the mosquito-borne viruses.
Yellowjackets are black-and-yellow wasps of the genus Vespula or Dolichovespula (though some can be black-and-white, the most notable of these being the bald-faced hornet, Dolichovespula maculata). They can be identified by their distinctive black-and-yellow color, small size (slightly larger than a bee), and entirely black antennae.

Trees
Populus tremuloides is a deciduous tree native to cooler areas of North America, one of several species referred to by the common name aspen. Populus tremuloides is the most widely distributed tree in North America, being found from Canada to central Mexico.
The yellow birch (Betula alleghaniensis) is a birch species native to eastern North America, from Nova Scotia, New Brunswick, and southern Quebec west to Minnesota, and south in the Appalachian Mountains to northern Georgia. They are medium-sized deciduous trees and can reach about 20 m (66 ft) tall, trunks up to 80 cm (31 in) in diameter. The bark is smooth and yellow-bronze, and the wood is extensively used for flooring, cabinetry, and toothpicks.
The thorny yellowwood is an Australian rainforest tree which has deep yellow wood.
Yellow poplar is a common name for Liriodendron, the tuliptree. The common name is inaccurate as this genus is not related to poplars.
The Handroanthus albus is a tree with yellow flowers native to the Cerrado of Brazil.

Fruits, vegetables, and eggs
Many fruits are yellow when ripe, such as lemons and bananas, their color derived from carotenoid pigments. Egg yolks gain their color from xanthophylls, also a type of carotenoid pigment.

Flowers
Yellow is a common color of flowers.

Other plants
Rapeseed (Brassica napus), also known as rape or oilseed rape, is a bright yellow flowering member of the family Brassicaceae (mustard or cabbage family).
Goldenrod is a yellow flowering plant in the family Asteraceae.

Minerals and chemistry
Yellowcake (also known as urania and uranic oxide) is concentrated uranium oxide, obtained through the milling of uranium ore. Yellowcake is used in the preparation of fuel for nuclear reactors and in uranium enrichment, one of the essential steps for creating nuclear weapons.
Titan yellow (also known as clayton yellow), chemical formula C28H19Na2O6S4 has been used to determine magnesium in serum and urine, but the method is prone to interference, making the ammonium phosphate method superior when analysing blood cells, food or fecal material.
Methyl yellow (p-Dimethylaminoazobenzene) is a pH indicator used to determine acidity. It changes from yellow at pH=4.0 to red at pH=2.9.
Yellow fireworks are produced by adding sodium compounds to the firework mixture. Sodium has a strong emission at 589.3 nm (D-line), a very slightly orange-tinted yellow.
Amongst the elements, sulfur and gold are most obviously yellow. Phosphorus, arsenic and antimony have allotropes which are yellow or whitish-yellow; fluorine and chlorine are pale yellowish gases.

Pigments

Yellow ochre (also known as Mars yellow, Pigment yellow 42, 43), hydrated ferric oxide (Fe2O3.H2O), is a naturally occurring pigment found in clays in many parts of the world. It is non-toxic and has been used in painting since prehistoric times.
Indian yellow is a transparent, fluorescent pigment used in oil paintings and watercolors. Originally magnesium euxanthate, it was claimed to have been produced from the urine of Indian cows fed only on mango leaves. It has now been replaced by synthetic Indian yellow hue.
Naples Yellow (lead antimonate yellow) is one of the oldest synthetic pigments, derived from the mineral bindheimite and used extensively up to the 20th century. It is toxic and nowadays is replaced in paint by a mixture of modern pigments.
Cadmium Yellow (cadmium sulfide, CdS) has been used in artists' paints since the mid-19th century. Because of its toxicity, it may nowadays be replaced by azo pigments.
Chrome Yellow (lead chromate, PbCrO4), derived from the mineral crocoite, was used by artists in the earlier part of the 19th century, but has been largely replaced by other yellow pigments because of the toxicity of lead.
Zinc yellow or zinc chromate is a synthetic pigment made in the 19th century, and used by the painter Georges Seurat in his pointilist paintings. He did not know that it was highly unstable, and would quickly turn brown.
Titanium Yellow (nickel antimony titanium yellow rutile, NiO.Sb2O5.20TiO2) is created by adding small amounts of the oxides of nickel and antimony to titanium dioxide and heating. It is used to produce yellow paints with good white coverage and has the LBNL paint code "Y10".
Gamboge is an orange-brown resin, derived from trees of the genus Garcinia, which becomes yellow when powdered. It was used as a watercolor pigment in the far east from the 8th century – the name "gamboge" is derived from "Cambodia" – and has been used in Europe since the 17th century.
Orpiment, also called King's Yellow or Chinese Yellow is arsenic trisulfide (As2S3) and was used as a paint pigment until the 19th century when, because of its high toxicity and reaction with lead-based pigments, it was generally replaced by Cadmium Yellow.
azo dye-based pigment (a brightly colored transparent or semitransparent dye with a white pigment) is used as the colorant in most modern paints requiring either a highly saturated yellow or simplicity of color mixing. The most common is the monoazo arylide yellow family, first marketed as Hansa Yellow.

Dyes
Curcuma longa, also known as turmeric, is a plant grown in India and Southeast Asia which serves as a dye for clothing, especially monks' robes; as a spice for curry and other dishes; and as a popular medicine. It is also used as a food coloring for mustard and other products.
Saffron, like turmeric, is one of the rare dyes that is also a spice and food colorant. It is made from the dried red stigma of the crocus sativus flower. It must be picked by hand and it takes 150 flowers to obtain a single gram of stigma, so it is extremely expensive. It probably originated in the Mediterranean or Southwest Asia, and its use was detailed in a 7th-century BC Assyrian botanical reference compiled under Ashurbanipal. It was known in India at the time of the Buddha, and after his death his followers decreed that monks should wear robes the color of saffron. Saffron was used to dye the robes of the senior Buddhist monks, while ordinary monks wore robes dyed with Gamboge or Curcuma longa, also known as Turmeric.
The color of saffron comes from crocin, a red variety of carotenoid natural pigment. The color of the dyed fabric varies from deep red to orange to yellow, depending upon the type of saffron and the process. Most saffron today comes from Iran, but it is also grown commercially in Spain, Italy and Kashmir in India, and as a boutique crop in New Zealand, the United Kingdom, France, Switzerland and other countries. In the United States, it has been cultivated by the Pennsylvania Dutch community since the early 18th century. Because of the high price of saffron, other similar dyes and spices are often sold under the name saffron; for instance, what is called Indian saffron is often really turmeric.

Reseda luteola, also known as dyers weed, yellow weed or weld, has been used as a yellow dye from neolithic times. It grew wild along the roads and walls of Europe, and was introduced into North America, where it grows as a weed. It was used as both as a yellow dye, whose color was deep and lasting, and to dye fabric green, first by dyeing it blue with indigo, then dyeing it with reseda luteola to turn it a rich, solid and lasting green. It was the most common yellow dye in Europe from the Middle Ages until the 18th century, when it was replaced first by the bark of the quercitron tree from North America, then by synthetic dyes. It was also widely used in North Africa and in the Ottoman Empire.
Gamboge is a deep saffron to mustard yellow pigment and dye. In Asia, it is frequently used to dye Buddhist monks' robes. Gamboge is most often extracted by tapping resin from various species of evergreen trees of the family Guttiferae, which grow in Cambodia, Thailand, and elsewhere in Southeast Asia. "Kambuj" (Sanskrit: कंबुज) is the ancient Sanskrit name for Cambodia.

Food coloring
The most common yellow food coloring in use today is called Tartrazine. It is a synthetic lemon yellow azo dye. It is also known as E number E102, C.I. 19140, FD&C yellow 5, acid yellow 23, food yellow 4. It is the yellow most frequently used such processed food products as corn and potato chips, breakfast cereals such as corn flakes, candies, popcorn, mustard, jams and jellies, gelatin, soft drinks (notably Mountain Dew), energy and sports drinks, and pastries. It is also widely used in liquid and bar soap, shampoo, cosmetics and medicines. Sometimes it is mixed with blue dyes to color processed products green.

It is typically labelled on food packages as "color", "tartrazine", or "E102". In the United States, because of concerns about possible health problems related to intolerance to tartrazine, its presence must be declared on food and drug product labels.

Another popular synthetic yellow coloring is Sunset Yellow FCF (also known as 'orange yellow S, FD&C yellow 6 and C.I. 15985) It is manufactured from aromatic hydrocarbons from petroleum. When added to foods sold in Europe, it is denoted by E number E110.

Source From Wikipedia

Red color in culture

Red is the color at the end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and the CMYK color model, and is the complementary color of cyan. Reds range from the brilliant yellow-tinged scarlet and vermillion to bluish-red crimson, and vary in shade from the pale red pink to the dark red burgundy. The red sky at sunset results from Rayleigh scattering, while the red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide. Iron oxide also gives the red color to the planet Mars. The red colour of blood comes from protein hemoglobin, while ripe strawberries, red apples and reddish autumn leaves are colored by anthocyanins.

Red pigment made from ochre was one of the first colors used in prehistoric art. The Ancient Egytians and Mayans colored their faces red in ceremonies; Roman generals had their bodies colored red to celebrate victories. It was also an important color in China, where it was used to colour early pottery and later the gates and walls of palaces. In the Renaissance, the brilliant red costumes for the nobility and wealthy were dyed with kermes and cochineal. The 19th century brought the introduction of the first synthetic red dyes, which replaced the traditional dyes. Red also became the color of revolution; Soviet Russia adopted a red flag following the Bolshevik Revolution in 1917, later followed by China, Vietnam, and other communist countries.

Since red is the color of blood, it has historically been associated with sacrifice, danger and courage. Modern surveys in Europe and the United States show red is also the color most commonly associated with heat, activity, passion, sexuality, anger, love and joy. In China, India and many other Asian countries it is the color of symbolizing happiness and good fortune.

Symbolism

Courage and sacrifice
Surveys show that red is the color most associated with courage. In western countries red is a symbol of martyrs and sacrifice, particularly because of its association with blood. Beginning in the Middle Ages, the Pope and Cardinals of the Roman Catholic Church wore red to symbolize the blood of Christ and the Christian martyrs. The banner of the Christian soldiers in the First Crusade was a red cross on a white field, the St. George's Cross. According to Christian tradition, Saint George was a Roman soldier who was a member of the guards of the Emperor Diocletian, who refused to renounce his Christian faith and was martyred. The Saint George's Cross became the Flag of England in the 16th century, and now is part of the Union Flag of the United Kingdom, as well as the Flag of the Republic of Georgia.

In 1587, Mary, Queen of Scots, accused of treason against Queen Elizabeth I, wore a red shirt at her execution, to proclaim that she was an innocent martyr.

The Thin Red Line was a famous incident in the Battle of Balaclava (1854) during the Crimean War, when a thin line of Scottish Highlander infantry, assisted by Royal Marines and Turkish infantrymen, repulsed a Russian cavalry charge. It was widely reported in the British press as an example of courage in the face of overwhelming odds and became a British military legend.

In the 19th-century novel The Red Badge of Courage by Stephen Crane, a story about the American Civil War, the red badge was the blood from a wound, by which a soldier could prove his courage.

Courtly love, the red rose, and Saint Valentine's Day
Red is the color most commonly associated with love, followed at a great distance by pink. It the symbolic color of the heart and the red rose, is closely associated with romantic love or courtly love and Saint Valentine's Day. Both the Greeks and the Hebrews considered red a symbol of love as well as sacrifice.

The Roman de la Rose, the Romance of the Rose, a thirteenth-century French poem, was one of the most popular works of literature of the Middle Ages. It was the allegorical search by the author for a red rose in an enclosed garden, symbolizing the woman he loved, and was a description of love in all of its aspects. Later, in the 19th century, British and French authors described a specific language of flowers – giving a single red rose meant 'I love you'.

Saint Valentine, a Roman Catholic Bishop or priest who was martyred in about 296 AD, seems to have had no known connection with romantic love, but the day of his martyrdom on the Roman Catholic calendar, Saint Valentine's Day (February 14), became, in the 14th century, an occasion for lovers to send messages to each other. In recent years the celebration of Saint Valentine' s day has spread beyond Christian countries to Japan and China and other parts of the world. The celebration of Saint Valentine's Day is forbidden or strongly condemned in many Islamic countries, including Saudi Arabia, Pakistan and Iran. In Saudi Arabia, in 2002 and 2011, religious police banned the sale of all Valentine's Day items, telling shop workers to remove any red items, as the day is considered a Christian holiday.

Happiness, celebration and ceremony
Red is the color most commonly associated with joy and well being. It is the color of celebration and ceremony. A red carpet is often used to welcome distinguished guests. Red is also the traditional color of seats in opera houses and theaters. Scarlet academic gowns are worn by new Doctors of Philosophy at degree ceremonies at Oxford University and other schools. In China, it is considered the color of good fortune and prosperity, and it is the color traditionally worn by brides. In Christian countries, it is the color traditionally worn at Christmas by Santa Claus, because in the 4th century the historic Saint Nicholas was the Greek Christian Bishop of Myra, in modern-day Turkey, and bishops then dressed in red.

Hatred, anger, aggression, passion, heat and war
While red is the color most associated with love, it also the color most frequently associated with hatred, anger, aggression and war. People who are angry are said to "see red." Red is the color most commonly associated with passion and heat. In ancient Rome, red was the color of Mars, the god of war—the planet Mars was named for him because of its red color.

Warning and danger
Red is the traditional color of warning and danger. In the Middle Ages, a red flag announced that the defenders of a town or castle would fight to defend it, and a red flag hoisted by a warship meant they would show no mercy to their enemy. In Britain, in the early days of motoring, motor cars had to follow a man with a red flag who would warn horse-drawn vehicles, before the Locomotives on Highways Act 1896 abolished this law. In automobile races, the red flag is raised if there is danger to the drivers. In international football, a player who has made a serious violation of the rules is shown a red penalty card and ejected from the game.

Several studies have indicated that red carries the strongest reaction of all the colors, with the level of reaction decreasing gradually with the colors orange, yellow, and white, respectively. For this reason, red is generally used as the highest level of warning, such as threat level of terrorist attack in the United States. In fact, teachers at a primary school in the UK have been told not to mark children's work in red ink because it encourages a "negative approach".

Red is the international color of stop signs and stop lights on highways and intersections. It was standardized as the international color at the Vienna Convention on Road Signs and Signals of 1968. It was chosen partly because red is the brightest color in daytime (next to orange), though it is less visible at twilight, when green is the most visible color. Red also stands out more clearly against a cool natural backdrop of blue sky, green trees or gray buildings. But it was mostly chosen as the color for stoplights and stop signs because of its universal association with danger and warning.

The color that attracts attention
Red is the color that most attracts attention. Surveys show it is the color most frequently associated with visibility, proximity, and extroverts. It is also the color most associated with dynamism and activity.

Red is used in modern fashion much as it was used in Medieval painting; to attract the eyes of the viewer to the person who is supposed to be the center of attention. People wearing red seem to be closer than those dressed in other colors, even if they are actually the same distance away. Monarchs, wives of Presidential candidates and other celebrities often wear red to be visible from a distance in a crowd. It is also commonly worn by lifeguards and others whose job requires them to be easily found.

Because red attracts attention, it is frequently used in advertising, though studies show that people are less likely to read something printed in red because they know it is advertising, and because it is more difficult visually to read than black and white text.

In different cultures and traditions
In China, red (simplified Chinese: 红; traditional Chinese: 紅; pinyin: hóng) is the symbol of fire and the south (both south in general and Southern China specifically). It carries a largely positive connotation, being associated with courage, loyalty, honor, success, fortune, fertility, happiness, passion, and summer. In Chinese cultural traditions, red is associated with weddings (where brides traditionally wear red dresses) and red paper is frequently used to wrap gifts of money or other objects. Special red packets (simplified Chinese: 红包; traditional Chinese: 紅包; pinyin: hóng bāo in Mandarin or lai see in Cantonese) are specifically used during Chinese New Year celebrations for giving monetary gifts. On the more negative side, obituaries are traditionally written in red ink, and to write someone's name in red signals either cutting them out of one's life, or that they have died. Red is also associated with either the feminine or the masculine (yin and yang respectively), depending on the source. The Little Red Book, a collection of quotations from Chairman Mao Tse-Tung, founding father of the People's Republic of China (PRC), was published in 1966 and widely distributed thereafter.

In Japan, red is a traditional color for a heroic figure. In the Indian subcontinent, red is the traditional color of bridal dresses, and is frequently represented in the media as a symbolic color for married women. The color is associated with purity, as well as with sexuality in marital relationships through its connection to heat and fertility. It is also the color of wealth, beauty, and the goddess Lakshmi.

In Central Africa, Ndembu warriors rub themselves with red paint during celebrations. Since their culture sees the color as a symbol of life and health, sick people are also painted with it. Like most Central African cultures, the Ndembu see red as ambivalent, better than black but not as good as white. In other parts of Africa, however, red is a color of mourning, representing death. Because red bears are associated with death in many parts of Africa, the Red Cross has changed its colors to green and white in parts of the continent.

The early Ottoman Turks led by the first Ottoman Sultan, Osman I, carried red banners symbolizing sovereignty, Ghazis and Sufism, until, according to legend, he saw a new red flag in his dream inlaid with a crescent.

Wedding dresses
In many Asian countries, red is the traditional color for a wedding dress today, symbolizing joy and good fortune.

In India, brides traditionally wear a red sari, called the sari of blood, offered by their father, signifying that his duties as a father are transferred to the new husband, and as a symbol of his wish for her to have children. Once married, the bride will wear a sari with a red border, changing it to a white sari if her husband dies. In Pakistan and India, some brides traditionally also have their hands and feet painted red with henna by the family of their new spouse, to bring happiness and signify their new status.

In religion
In Christianity, red is associated with the blood of Christ and the sacrifice of martyrs. In the Roman Catholic Church it is also associated with pentecost and the Holy Spirit. Since 1295, it is the color worn by Cardinals, the senior clergy of the Roman Catholic Church. Red is the liturgical color for the feasts of martyrs, representing the blood of those who suffered death for their faith. It is sometimes used as the liturgical color for Holy Week, including Palm Sunday and Good Friday, although this is a modern (20th-century) development. In Catholic practice, it is also the liturgical color used to commemorate the Holy Spirit (for this reason it is worn at Pentecost and during Confirmation masses). Because of its association with martyrdom and the Spirit, it is also the color used to commemorate the Apostles (except for the Apostle St. John, who was not martyred, where white is used), and as such, it is used to commemorate bishops, who are the successors of the Apostles (for this reason, when funeral masses are held for bishops, cardinals, or popes, red is used instead of the white that would ordinarily be used).
In Buddhism, red is one of the five colors which are said to have emanated from the Buddha when he attained enlightenment, or nirvana. It is particularly associated with the benefits of the practice of Buddhism; achievement, wisdom, virtue, fortune and dignity. It was also believed to have the power to resist evil. In China red was commonly used for the walls, pillars, and gates of temples.
In the Shinto religion of Japan, the gateways of temples, called torii, are traditionally painted vermilion red and black. The torii symbolizes the passage from the profane world to a sacred place. The bridges in the gardens of Japanese temples are also painted red (and usually only temple bridges are red, not bridges in ordinary gardens), since they are also passages to sacred places. Red was also considered a color which could expel evil and disease.

Military uses
NATO Military Symbols for Land Based Systems uses red to denote hostile forces, hence the terms "red team" and "Red Cell" to denote challengers during exercises.

The red uniform
The red military uniform was adopted by the English Parliament's New Model Army in 1645, and was still worn as a dress uniform by the British Army until the outbreak of the First World War in August 1914. Ordinary soldiers wore red coats dyed with madder, while officers wore scarlet coats dyed with the more expensive cochineal. This led to British soldiers being known as red coats.

In the modern British army, scarlet is still worn by the Foot Guards, the Life Guards, and by some regimental bands or drummers for ceremonial purposes. Officers and NCOs of those regiments which previously wore red retain scarlet as the color of their "mess" or formal evening jackets. The Royal Gibraltar Regiment has a scarlet tunic in its winter dress.

Scarlet is worn for some full dress, military band or mess uniforms in the modern armies of a number of the countries that made up the former British Empire. These include the Australian, Jamaican, New Zealand, Fijian, Canadian, Kenyan, Ghanaian, Indian, Singaporean, Sri Lankan and Pakistani armies.

The musicians of the United States Marine Corps Band wear red, following an 18th-century military tradition that the uniforms of band members are the reverse of the uniforms of the other soldiers in their unit. Since the US Marine uniform is blue with red facings, the band wears the reverse.

Red Serge is the uniform of the Royal Canadian Mounted Police, created in 1873 as the North-West Mounted Police, and given its present name in 1920. The uniform was adapted from the tunic of the British Army. Cadets at the Royal Military College of Canada also wear red dress uniforms.

The Brazilian Marine Corps wears a red dress uniform.

In sports
The first known team sport to feature red uniforms was chariot racing during the late Roman Empire. The earliest races were between two chariots, one driver wearing red, the other white. Later, the number of teams was increased to four, including drivers in light green and sky blue. Twenty-five races were run in a day, with a total of one hundred chariots participating.

Today many sports teams throughout the world feature red on their uniforms. Along with blue, red is the most commonly used non-white color in sports. Numerous national sports teams wear red, often through association with their national flags. A few of these teams feature the color as part of their nickname such as Spain (with their association football (soccer) national team nicknamed La Furia Roja or "The Red Fury") and Belgium (whose football team bears the nickname Rode Duivels or "Red Devils").

In Major League Baseball the color is featured in the league's logo. Major League Baseball is especially well known for red teams. The Cincinnati Red Stockings are the oldest professional baseball team, dating back to 1869. The franchise soon relocated to Boston and is now the Atlanta Braves, but its name survives as the origin for both the Cincinnati Reds and Boston Red Sox. During the 1950s when red was strongly associated with communism, the modern Cincinnati team was known as the "Redlegs" and the term was used on baseball cards. After the red scare faded, the team was known as the "Reds" again. 11 teams either regularly features red caps or utilize the color in their uniforms.

In the NHL, red jerseys are worn by the Detroit Red Wings, Washington Capitals, Calgary Flames, Carolina Hurricanes, Chicago Blackhawks, Colorado Avalanche, Minnesota Wild, Montreal Canadiens, Ottawa Senators, Phoenix Coyotes, and the New Jersey Devils.

In club association football (soccer), red is a commonly used color throughout the world. A number of teams' nicknames feature the color. A red penalty card is issued to a player who commits a serious infraction: the player is immediately disqualified from further play and his team must continue with one less player for the game's duration.

In rugby union, Ireland's Munster rugby, New Zealand's Canterbury provincial team and the Crusaders Super 14 rugby side wear red as a major color in their playing strips.

In the NFL, many teams feature a shade of the color as either the primary color of team's dark "home" jersey (or an alternate thereof) or its "throwback" jersey. This includes the Arizona Cardinals, Atlanta Falcons, Houston Texans, Kansas City Chiefs, New England Patriots, San Francisco 49ers, Tampa Bay Buccaneers, and Washington Redskins. In order to challenge to a call made on the field, coaches have to throw a red flag onto the football field.

In the NBA the color is featured in the league's logo. Eleven teams prominently feature the color (or shades of the color) with the Cleveland Cavaliers using a deeper shade of the color, wine.

In boxing, red is often the color used on a fighter's gloves. George Foreman wore the same red trunks he used during his loss to Muhammad Ali when he defeated Michael Moorer 20 years later to regain the title he lost. Boxers named or nicknamed "red" include Red Burman, Ernie "Red" Lopez, and his brother Danny "Little Red" Lopez.

Rosso Corsa is the red international motor racing color of cars entered by teams from Italy. Since the 1920s Italian race cars of Alfa Romeo, Maserati, Lancia, and later Ferrari and Abarth have been painted with a color known as rosso corsa ("racing red"). National colors were mostly replaced in Formula One by commercial sponsor liveries in 1968, but unlike most other teams, Ferrari always kept the traditional red, although the shade of the color varies.

Red flag and revolution
In the Middle Ages, ships in combat hoisted a long red streamer, called the Baucans, to signify a fight to the death. In the 17th century, a red flag signalled defiance. A besieged castle or city would raise a red flag to tell the attackers that they would not surrender.

The red flag appeared as a political symbol during the French Revolution, after the fall of Bastille. A law adopted by the new government on October 20, 1789 authorized the Garde Nationale to raise the red flag in the event of a riot, to signal that the Garde would imminently intervene. During a demonstration on the Champs de Mars on July 17, 1791, the Garde Nationale fired on the crowd, killed up to fifty people. The government was denounced by the more radical revolutionaries. In the words of his famous hymn, the Marseillaise, Rouget de Lisle wrote: "Against us they have raised the bloody flag of tyranny!" (Contre nous de la tyrannie, l'entendard sanglant est leve). Beginning in 1790, the most radical revolutionaries adopted the red flag themselves, to symbolize the blood of those killed in the demonstrations, and to call for the repression of those they considered counter-revolutionary.

During the French Revolution, many in the Paris crowds also wore a red phrygian cap, a symbol of liberty, modeled after the caps worn in ancient Rome by freed slaves; but the colors of the Revolution finally became blue, white and red. The red in the French flag was taken from the emblem of the city of Paris, where it represented the city's patron saint, Saint Denis.

Karl Marx published the Communist Manifesto in February 1848, with little attention. However, a few days later the French Revolution of 1848 broke out, which replaced the monarchy of Louis Philippe with the Second French Republic. In June 1848, Paris workers, disenchanted with the new government, built barricades and raised red flags. The new government called in the French Army to put down the uprising, the first of many such confrontations between the army and the new worker's movements in Europe.

Red was also the color of the movement to unify Italy, led by Giuseppe Garibaldi. His followers were known as the camicie rosse, or (redshirts) during the fight for Italian Risorgimento in 1860.

In 1870, following the stunning defeat of the French Army by the Germans in the Franco-Prussian War, French workers and socialist revolutionaries seized Paris and created the Paris Commune. The Commune lasted for two months before it was crushed by the French Army, with much bloodshed. The original red banners of the Commune became icons of the socialist revolution; in 1921 members of the French Communist Party came to Moscow and presented the new Soviet government with one of the original Commune banners; it was placed (and is still in place) in the tomb of Vladimir Lenin, next to his open coffin.

With the victory of the Bolsheviks in the Russian Revolution of 1917, the red flag, with a hammer to symbolize the workers and sickle to symbolize peasants, became the official flag of Russia, and, in 1923, of the Soviet Union. It remained so until the breakup of the Soviet Union in 1991.

After the Communist Party of China took power in 1949, the flag of China became a red flag with a large star symbolizing the Communist Party, and smaller stars symbolizing workers, peasants, the urban middle class and rural middle class. The flag of the Communist Party of China became a red banner with a hammer and sickle, similar to that on the Soviet flag. In the 1950s and 1960s, other Communist regimes such as Vietnam and Laos also adopted red flags. Some Communist countries, such as Cuba, chose to keep their old flags; and other countries used red flags which had nothing to do with Communism or socialism; the red flag of Nepal, for instance, represents the national flower.

Use by political movements
In 18th-century Europe, red was usually associated with the monarchy and with those in power. The Pope wore red, as did the Swiss Guards of the Kings of France, the soldiers of the British Army and the Danish Army.

The French Revolution saw red used by the Jacobins as a symbol of the martyrs of the Revolution. In the nineteenth century, with the Industrial Revolution and the rise of worker's movements, it became the color of socialism (especially the Marxist variant), and, with the Paris Commune of 1870, of revolution.

In the 20th century, red was the color first of the Russian Bolsheviks and then, after the success of the Russian Revolution of 1917, of Communist Parties around the world.

Red also became the color of many social democratic parties in Europe, including the Labour Party in Britain (founded 1900); the Social Democratic Party of Germany (whose roots went back to 1863) and the French Socialist Party, which dated back under different names, to 1879. The Socialist Party of America (1901–72) and the Communist Party USA (1919) both also chose red as their color.

Members of the Christian-Social People's Party in Liechtenstein (founded 1918) advocated an expansion of democracy and progressive social policies, and were often referred to disparagingly as "Reds" for their social liberal leanings and party colors.

The Communist Party of China, founded in 1920, adopted the red flag and hammer and sickle emblem of the Soviet Union, which became the national symbols when the Party took power in China in 1949. Under Party leader Mao Zedong, the Party anthem became "The East Is Red", and Mao Zedong himself was sometimes referred to as a "red sun". During the Cultural Revolution in China, Party ideology was enforced by the Red Guards, and the sayings of Mao Zedong were published as a small red book in hundreds of millions of copies. Today the Communist Party of China claims to be the largest political party in the world, with eighty million members.

Beginning in the 1960s and the 1970s, paramilitary extremist groups such as the Red Army Faction in Germany, the Japanese Red Army and the Shining Path Maoist movement in Peru used red as their color. But in the 1980s, some European socialist and social democratic parties, such as the Labour Party in Britain and the Socialist Party in France, moved away from the symbolism of the far left, keeping the red color but changing their symbol to a less-threatening red rose.

Red is used around the world by political parties of the left or center-left. In the United States, it is the color of the Communist Party USA, of the Social Democrats, USA, and in Puerto Rico, of the Popular Democratic Party of Puerto Rico.

In the United States, political commentators often refer to the "red states", which traditionally vote for Republican candidates in presidential elections, and "blue states", which vote for the Democratic candidate. This convention is relatively recent: before the 2000 presidential election, media outlets assigned red and blue to both parties, sometimes alternating the allocation for each election. Fixed usage was established during the 39-day recount following the 2000 election, when the media began to discuss the contest in terms of "red states" versus "blue states".

Social and special interest groups
Such names as Red Club (a bar), Red Carpet (a discothèque) or Red Cottbus and Club Red (event locations) suggest liveliness and excitement. The Red Hat Society is a social group founded in 1998 for women 50 and over. Use of the color red to call attention to an emergency situation is evident in the names of such organizations as the Red Cross (humanitarian aid), Red Hot Organization (AIDS support), and the Red List of Threatened Species (of IUCN). In reference to humans, term "red" is often used in the West to describe the indigenous peoples of the Americas.

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