Yellow theme by mizzourahslim
Download: Yellow.p3t
(1 background)
| Yellow | |
|---|---|
 .jpg)      | |
| Spectral coordinates | |
| Wavelength | 575–585[1] nm |
| Frequency | 521–512 THz |
 Color coordinates | |
| Hex triplet | #FFFF00 |
| sRGBB (r, g, b) | (255, 255, 0) |
| HSV (h, s, v) | (60°, 100%, 100%) |
| CIELChuv (L, C, h) | (97, 107, 86°) |
| Source | HTML/CSS[2] |
| B: Normalized to [0–255] (byte) H: Normalized to [0–100] (hundred) | |
Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575–585 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 photo damage in some cases.[3] Sunlight has a slight yellowish hue when the Sun is near the horizon, due to atmospheric scattering of shorter wavelengths (green, blue, and violet).
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.[4] In the early Christian church, yellow was the color associated with the Pope and the golden keys of the Kingdom, but it was also associated with Judas Iscariot and used to mark heretics. In the 20th century, Jews in Nazi-occupied Europe were forced to wear a yellow star. In China, bright 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.[5]
According to surveys in Europe, Canada, the United States and elsewhere, yellow is the color people most often associate with amusement, gentleness, humor, happiness, and spontaneity; however it can also be associated with duplicity, envy, jealousy, greed, justice, and, in the U.S., cowardice.[6] In Iran it has connotations of pallor/sickness,[7] but also wisdom and connection.[8] In China and many Asian countries, it is seen as the color of happiness, glory, harmony and wisdom.[9]
Etymology[edit]
The word yellow is from the Old English geolu, geolwe (oblique case), meaning "yellow, and yellowish", derived from the Proto-Germanic word gelwaz "yellow". It has the same Indo-European base, gel-, as the words gold and yell; gʰel- means both bright and gleaming, and to cry out.[10]
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.[11] According to the Oxford English Dictionary, the oldest known use of this word in English is from The Epinal Glossary in 700.[12]
Science and nature[edit]
Optics, color printing, and computer screens[edit]
| Process Yellow (subtractive primary) | |
|---|---|
| Color coordinates | |
| Hex triplet | #FFEF00 |
| sRGBB (r, g, b) | (255, 239, 0) |
| HSV (h, s, v) | (56°, 100%, 100%) |
| CIELChuv (L, C, h) | (93, 103, 80°) |
| Source | [1] CMYK |
| ISCC–NBS descriptor | Vivid greenish yellow |
| B: Normalized to [0–255] (byte) | |
-
-
Mixing all three theoretically results in black, but imperfect ink formulations do not give true black, which is why an additional K component is needed. -
An example of color printing from 1902. Combining images in yellow, magenta and cyan creates a full-color picture. This is called the CMYK color model. -
On a computer display, yellow is created by combining green and red light at the right intensity on a black screen.
Yellow is found between green and red 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 subtractive primary colors of ink along with magenta and cyan. Together with black, they can be overlaid in the right combination 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"). 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[edit]
Traditionally, the complementary color of yellow is purple; the two colors are opposite each other on the color wheel long used by painters.[13] 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.[14]
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."[15] 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.[16] 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."[17]
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[edit]
Lasers emitting in the yellow part of the spectrum are less common and more expensive than most other colors.[18] 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 aluminum 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").[19] 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.[20] The use of yellow lasers at 589 nm and 594 nm have recently become more widespread thanks to the field of optogenetics.[21]
Astronomy[edit]
Stars of spectral classes F and G have color temperatures that make them look "yellowish".[22] 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.[23] 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.[24][25]
Supergiant stars are rarely yellow supergiants because F and G class supergiants are physically unstable; they are most often a transitional phase between blue supergiants and red supergiants. Some yellow supergiants, the Cepheid variables, pulsate with a period proportional to their absolute magnitude; hence, if their apparent magnitude is known, the distance to them can be calculated with great precision.[26] Cepheid variables were hence used to determine distances within and beyond the Milky Way galaxy. The most famous example is the current North Pole star, Polaris.
Biology[edit]
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.[3]
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, maize, 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.
-
-
Daffodils in Cornwall -
Bananas, like autumn leaves, canaries and egg yolks, get their yellow color from natural pigments called carotenoids. -
-
Duckling chicks
.jpg)
Fish[edit]
- Yellowtail is the common name for dozens of different fish species that have yellow tails or a yellow body. Most of the time, yellowtail(fish) actually refers to Japanese amberjack, a fish that lives between Japan and Hawaii.
- 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.
- Smallmouth yellowfish (Labeobarbus aeneus) is a species of ray-finned fish in the genus Labeobarbus. It has become an invasive species in rivers of the Eastern Cape, South Africa, such as the Mbhashe River.
Insects[edit]
- 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[edit]
- 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,[27] 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.
History, art, and fashion[edit]
Prehistory[edit]
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.