"Rainbow A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It takes the form of a multicoloured circular arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the sun. Rainbows can be full circles. However, the observer normally sees only an arc formed by illuminated droplets above the ground, and centered on a line from the sun to the observer's eye. In a primary rainbow, the arc shows red on the outer part and violet"
"number of colour bands of a rainbow may therefore be different from the number of bands in a spectrum, especially if the droplets are particularly large or small. Therefore, the number of colours of a rainbow is variable. If, however, the word ""rainbow"" is used inaccurately to mean ""spectrum"", it is the number of main colours in the spectrum. The question of whether everyone sees seven colours in a rainbow is related to the idea of linguistic relativity. Suggestions have been made that there is universality in the way that a rainbow is perceived. However, more recent research suggests that"
"on the inner side. This rainbow is caused by light being refracted when entering a droplet of water, then reflected inside on the back of the droplet and refracted again when leaving it. In a double rainbow, a second arc is seen outside the primary arc, and has the order of its colours reversed, with red on the inner side of the arc. This is caused by the light being reflected twice on the inside of the droplet before leaving it. A rainbow is not located at a specific distance from the observer, but comes from an optical illusion caused"
"ROYGBIV ROYGBIV or Roy G. Biv is an initialism for the sequence of hues commonly described as making up a rainbow: red, orange, yellow, green, blue, indigo and violet. The initialism is sometimes referred to in reverse order, as VIBGYOR. In Classical Antiquity, Aristotle claimed there was a scale of seven basic colors. In the Renaissance, several artists tried to establish a new sequence of up to seven primary colors from which all other colors could be mixed. In line with this artistic tradition, Newton divided his color circle, which he constructed to explain additive color mixing, into seven colors."
"color in question. The familiar colors of the rainbow in the spectrum—named using the Latin word for ""appearance"" or ""apparition"" by Isaac Newton in 1671—include all those colors that can be produced by visible light of a single wavelength only, the ""pure spectral"" or ""monochromatic"" colors. The table at right shows approximate frequencies (in terahertz) and wavelengths (in nanometers) for various pure spectral colors. The wavelengths listed are as measured in air or vacuum (see refractive index). The color table should not be interpreted as a definitive list—the pure spectral colors form a continuous spectrum, and how it is divided"
"with red on the outside. Double rainbows are produced by two internal reflections with angular size of 50.5° to 54° with violet on the outside. Within the ""primary rainbow"" (the lowest, and also normally the brightest rainbow) the arc of a rainbow shows red on the outer (or upper) part of the arc, and violet on the inner section. This rainbow is caused by light being reflected once in droplets of water. In a double rainbow, a second arc may be seen above and outside the primary arc, and has the order of its colors reversed (red faces inward toward"
"the rainbow identified by Isaac Newton, and it does not have its own wavelength of light. For this reason, it is called a ""non-spectral color"". It exists in culture and art, but not, in the same way that violet does, in optics. It is simply a combination, in various proportions, of two primary colors, red and blue. In color theory, a ""purple"" is defined as any non-spectral color between violet and red (excluding violet and red themselves). The spectral colors violet and indigo are not purples according to color theory, but they are purples according to common English usage since"
"and no banding of any type is seen in a black-and-white photograph of a rainbow (only a smooth gradation of intensity to a maxima, then fading to a minima at the other side of the arc). For colors seen by a normal human eye, the most commonly cited and remembered sequence, in English, is Newton's sevenfold red, orange, yellow, green, blue, indigo and violet (popularly memorized by mnemonics like Roy G. Biv). However, color-blind persons will see fewer colors. Rainbows can be caused by many forms of airborne water. These include not only rain, but also mist, spray, and airborne"
"Any distinct bands perceived are an artefact of human colour vision, and no banding of any type is seen in a black-and-white photo of a rainbow, only a smooth gradation of intensity to a maximum, then fading towards the other side. For colours seen by the human eye, the most commonly cited and remembered sequence is Newton's sevenfold red, orange, yellow, green, blue, indigo and violet, remembered by the mnemonic ""Richard Of York Gave Battle In Vain"" (ROYGBIV). Rainbows can be caused by many forms of airborne water. These include not only rain, but also mist, spray, and airborne dew."
"inside a primary rainbow is brighter than the sky outside of the bow. This is because each raindrop is a sphere and it scatters light over an entire circular disc in the sky. The radius of the disc depends on the wavelength of light, with red light being scattered over a larger angle than blue light. Over most of the disc, scattered light at all wavelengths overlaps, resulting in white light which brightens the sky. At the edge, the wavelength dependence of the scattering gives rise to the rainbow. Light of primary rainbow arc is 96% polarised tangential to the"
"as ""blue"" would today be regarded as cyan, and what Newton called ""indigo"" would today be considered blue. The colour pattern of a rainbow is different from a spectrum, and the colours are less saturated. There is spectral smearing in a rainbow owing to the fact that for any particular wavelength, there is a distribution of exit angles, rather than a single unvarying angle. In addition, a rainbow is a blurred version of the bow obtained from a point source, because the disk diameter of the sun (0.5°) cannot be neglected compared to the width of a rainbow (2°). The"
"Rainbow flag A rainbow flag is a multicolored flag consisting of the colors of the rainbow. The actual colors shown differ, but many of the designs are based on the traditional scheme of red, orange, yellow, green, blue, indigo, and violet. There are several independent rainbow flags in use today. The most widely known worldwide is the pride flag representing LGBT pride (since 1978). The peace flag is especially popular in Italy (since 1961). The International Co-operative Alliance adopted a rainbow flag in 1925. A similar flag is used in Andean indigenism in Peru and Bolivia to represent the legacy"
"rainbow logo flag on a white field, to clearly promote and strengthen the cooperative image, but still use the rainbow image. Other organizations sometimes use the traditional rainbow flag as a symbol of cooperation. Like the rainbow, this flag is a symbol of hope and peace. The seven colours from flags around the world fly in harmony. Each of the seven colours in the co-operative flag have been assigned the following meaning: The ICA has been flying a flag with its official logo since April 2001, when its Board decided to replace the traditional rainbow flag. Its use by a"
"than the red light. Due to this angle, blue is seen on the inside of the arc of the primary rainbow, and red on the outside. The result of this is not only to give different colours to different parts of the rainbow, but also to diminish the brightness. (A ""rainbow"" formed by droplets of a liquid with no dispersion would be white, but brighter than a normal rainbow.) The light at the back of the raindrop does not undergo total internal reflection, and some light does emerge from the back. However, light coming out the back of the raindrop"
"that time largely influenced by pioneering gay activist Allen Ginsberg. The flag originally comprised eight stripes; Baker assigned specific meaning to each of the colors: Thirty volunteers hand-dyed and stitched the first two flags for the parade. After the assassination of gay San Francisco City Supervisor Harvey Milk on November 27, 1978, demand for the rainbow flag greatly increased. To meet demand, the Paramount Flag Company began selling a version of the flag using stock rainbow fabric with seven stripes: red, orange, yellow, green, turquoise, blue, and violet. As Baker ramped up production of his version of the flag, he"
"compared to those of the primary bow. The secondary rainbow is fainter than the primary because more light escapes from two reflections compared to one and because the rainbow itself is spread over a greater area of the sky. Each rainbow reflects white light inside its coloured bands, but that is ""down"" for the primary and ""up"" for the secondary. The dark area of unlit sky lying between the primary and secondary bows is called Alexander's band, after Alexander of Aphrodisias who first described it. Unlike a double rainbow that consists of two separate and concentric rainbow arcs, the very"
"an azure sky, a biblical symbol of peace. The colors in the rainbow from top to bottom are red, orange, yellow, green, and blue. Behind the coat of arms there are five cobalt blue and white striped flags representing the flags of the Federal Republic of Central America; one of those flags is risen straight up behind and over the triangle, hanging loosely around its spear, and the other four flags are risen half way and stretch out like wings from behind the triangle's sides, two on each side, one over another. The flags hang loosely on their sides, creating"
"connecting them whose internal vertices are assigned distinct colors. Rainbow coloring In graph theory, a path in an edge-colored graph is said to be rainbow if no color repeats on it. A graph is said to be rainbow-connected (or rainbow colored) if there is a rainbow path between each pair of its vertices. If there is a rainbow shortest path between each pair of vertices, the graph is said to be strongly rainbow-connected (or strongly rainbow colored). The rainbow connection number of a graph formula_1 is the minimum number of colors needed to rainbow-connect formula_1, and is denoted by formula_3."
"at intermediate angles brightens the inside of the rainbow. The minimum deviation angle for the secondary bow is about 230°. The fact that this angle is greater than 180° makes the secondary bow an inside-out version of the primary. Its colors are reversed, and light which is deviated at greater angles brightens the sky ""outside"" the bow. Between the two bows lies an area of unlit sky referred to as Alexander's band. Light which is reflected by raindrops in this region of the sky cannot reach the observer, though it may contribute to a rainbow seen by another observer elsewhere."
"be confused with ice halos, which are very common around the world and visible much more often than rainbows (of any order), yet are unrelated to rainbows. The circumzenithal and circumhorizontal arcs are two related optical phenomena similar in appearance to a rainbow, but unlike the latter, their origin lies in light refraction through hexagonal ice crystals rather than liquid water droplets. This means that they are not rainbows, but members of the large family of halos. Both arcs are brightly coloured ring segments centred on the zenith, but in different positions in the sky: The circumzenithal arc is notably"
"had become very well known in the 20th century. The present flag shows the ICA seven-color logo on a white background. The logo depicts a quarter rainbow with a flock of stylized doves of peace scattering from the top and the letters ICA underneath. The rainbow has only six stripes (red, orange, yellow, green, light blue, dark blue) and the seventh color (purple) appears in the lettering under the rainbow. The flag exists in four different versions showing the ICA acronym in different languages (ACI in Spanish, Italian and French, IGB in German, and МКА in Russian). International Co-operative Alliance"
"avoid disease appears to pre-date the Incan empire. In New Age and Hindu philosophy, the seven colours of the rainbow represent the seven chakras, from the first chakra (red) to the seventh chakra (violet). Rainbows are generally described as very colourful and peaceful. The rainbow occurs often in paintings. Frequently these have a symbolic or programmatic significance (for example, Albrecht Dürer's Melancholia I). In particular, the rainbow appears regularly in religious art (for example, Joseph Anton Koch's ""Noah's Thank Offering""). Romantic landscape painters such as Turner and Constable were more concerned with recording fleeting effects of light (for example, Constable's"
"rainbow flag design was adopted during October 1996. The white color of the cloth represents purity. Rainbows are the biblical symbol of peace, happiness, goodness. The number of bands of the rainbow equal to the number of candles in the Menorah, one of the national religious Jewish symbols. The Menorah speaks of the creation of the world in seven days, and the number of bands of the rainbow emphasizes the connection with the ancient Jewish symbol. Also, the rainbow may symbolize the Seven Noahide laws. Flag of the Jewish Autonomous Oblast The Jewish Autonomous Oblast is situated in the Far"
"Indigo Indigo is a deep and rich color close to the color wheel blue (a primary color in the RGB color space), as well as to some variants of ultramarine. It is traditionally regarded as a color in the visible spectrum, as well as one of the seven colors of the rainbow: the color between violet and blue; however, sources differ as to its actual position in the electromagnetic spectrum. The color indigo is named after the indigo dye derived from the plant ""Indigofera tinctoria"" and related species. The first known recorded use of indigo as a color name in"
"to it. Gilbert Baker designed the rainbow Pride flag for the 1978 San Francisco Gay Freedom Celebration. The flag does not depict an actual rainbow. Rather, the colors of the rainbow are displayed as horizontal stripes, with red at the top and violet at the bottom. It represents the diversity of gays and lesbians around the world. In the original eight-color version, pink stood for sexuality, red for life, orange for healing, yellow for the sun, green for nature, turquoise for art, indigo for harmony, and violet for spirit. A copy of the original 20-by-30 foot, eight-color flag was remade"
"Rainbow coloring In graph theory, a path in an edge-colored graph is said to be rainbow if no color repeats on it. A graph is said to be rainbow-connected (or rainbow colored) if there is a rainbow path between each pair of its vertices. If there is a rainbow shortest path between each pair of vertices, the graph is said to be strongly rainbow-connected (or strongly rainbow colored). The rainbow connection number of a graph formula_1 is the minimum number of colors needed to rainbow-connect formula_1, and is denoted by formula_3. Similarly, the strong rainbow connection number of a graph"
"a number of vertices equal to the given number of colors can be embedded on the surface. The torus has ""g"" = 1, so χ = 0. Therefore, as the formula states, any subdivision of the torus into regions can be colored using at most seven colors. The illustration shows a subdivision of the torus in which each of seven regions are adjacent to each other region; this subdivision shows that the bound of seven on the number of colors is tight for this case. The boundary of this subdivision forms an embedding of the Heawood graph onto the torus."
"number of non-cooperative groups led to confusion in several countries around the world. Another variation of rainbow flag is used by Jewish Autonomous Oblast, situated in the Far Eastern Federal District of Russia, by the Chinese border. Proportions 2:3. Adopted first of October 1996. The Jewish Autonomous Oblast has a flag with a seven-colour rainbow. The number of colours is meant to symbolize the seven-branched Jewish Menorah. The rainbow flag was popularized as a symbol of the gay community by San Francisco artist Gilbert Baker in 1978. The different colors are often associated with ""diversity"" in the gay community (but"
"6) with their reflected counterparts below it (7, 8). Occasionally a shower may happen at sunrise or sunset, where the shorter wavelengths like blue and green have been scattered and essentially removed from the spectrum. Further scattering may occur due to the rain, and the result can be the rare and dramatic monochrome or red rainbow. In addition to the common primary and secondary rainbows, it is also possible for rainbows of higher orders to form. The order of a rainbow is determined by the number of light reflections inside the water droplets that create it: One reflection results in"
"Circumzenithal arc The circumzenithal arc, also called the circumzenith arc (CZA), upside-down rainbow, and the Bravais arc, is an optical phenomenon similar in appearance to a rainbow, but belonging to the family of halos arising from refraction of sunlight through ice crystals, generally in cirrus or cirrostratus clouds, rather than from raindrops. The arc is located at a considerable distance (approximately 46°) above the sun and at most forms a quarter of a circle centered on the zenith. It has been called ""a smile in the sky"", its first impression being that of an upside-down rainbow. The CZA is one"
"is what constitutes the rainbow for that observer. The whole system composed by the sun's rays, the observer's head, and the (spherical) water drops has an axial symmetry around the axis through the observer's head and parallel to the sun's rays. The rainbow is curved because the set of all the raindrops that have the right angle between the observer, the drop, and the sun, lie on a cone pointing at the sun with the observer at the tip. The base of the cone forms a circle at an angle of 40–42° to the line between the observer's head and"
"The reflection rainbow appears above the horizon. It intersects the normal rainbow at the horizon, and its arc reaches higher in the sky, with its centre as high above the horizon as the normal rainbow's centre is below it. Due to the combination of requirements, a reflection rainbow is rarely visible. Up to eight separate bows may be distinguished if the reflected and reflection rainbows happen to occur simultaneously: The normal (non-reflection) primary and secondary bows above the horizon (1, 2) with their reflected counterparts below it (3, 4), and the reflection primary and secondary bows above the horizon (5,"
"or several narrow, faintly coloured bands can be seen bordering the violet edge of a rainbow; i.e., inside the primary bow or, much more rarely, outside the secondary. These extra bands are called ""supernumerary rainbows"" or ""supernumerary bands""; together with the rainbow itself the phenomenon is also known as a ""stacker rainbow"". The supernumerary bows are slightly detached from the main bow, become successively fainter along with their distance from it, and have pastel colours (consisting mainly of pink, purple and green hues) rather than the usual spectrum pattern. The effect becomes apparent when water droplets are involved that have"