Editing Purple (section)

== In science and nature ==
=== Optics ===
The meanings of the color terms violet and purple varies even among native speakers of English, for example between United Kingdom and United States.<ref name="Computational evidence of first ext">{{cite journal |last1=Tager |first1=A. |last2=Kirchner |first2=E. |last3=Fedorovskaya |first3=E. |title=Computational evidence of first extensive usage of violet in the 1860s |journal=Color Research & Application |date=2021 |volume=46 |issue=5 |pages=961–977 |doi=10.1002/col.22638|s2cid=233671776 }}</ref> Optics research on purple and violet contains contributions of authors from different countries and different native languages, it is likely to be inconsistent in the use and meaning of the two colors.

According to some speakers/authors of English, purple, unlike violet, is not one of the colors of the [[visible spectrum]].<ref name="StClair">{{Cite book|title=The Secret Lives of Colour|last=St. Clair|first=Kassia|publisher=John Murray|year=2016|isbn=978-1-4736-3081-9|location=London|page=159|oclc=936144129}}</ref> It was not one of the colors of the rainbow identified by [[Isaac Newton]]. According to some authors, purple does not have its own [[wavelength]] of light. For this reason, it is sometimes called a ''[[Spectral color#Extra-spectral colors|non-spectral color]]''. According to some speakers of English, purple is simply a combination, in various proportions, of two primary colors, red and blue.<ref>{{cite journal |last1=Matschi |first1=M. |title=Color terms in English: Onomasiological and Semasiological aspects |journal=Onomasiology Online |date=2005 |volume=5 |pages=56–139 }}</ref> According to other speakers of English, the same range of colors is called violet.<ref name="The ANLAB colour system and the dye">{{cite journal|last1=Cooper|first1=A.C.|last2=McLaren|first2=K.|date=1973|title=The ANLAB colour system and the dyer's variables of "shade" and strength|journal=Journal of the Society of Dyers and Colourists|volume=89|issue=2|pages=41–45|doi=10.1111/j.1478-4408.1973.tb03128.x}}</ref>

In some textbooks of [[color theory]], and depending on the geographical-cultural origin of the author, a "purple" is defined as any [[Spectral color#Extra-spectral colors|non-spectral color]] between [[Violet (color)|violet]] and red (excluding violet and red themselves).<ref name="gilbert222" /> In that case, the [[spectral color]] violet would not be shades of purple. For other speakers of English, these colors are shades of purple.

In the traditional color wheel long used by painters, purple is placed between crimson and violet.<ref>See ''Oxford English Dictionary'' definition</ref> However, also here there is much variation in color terminology depending on cultural background of the painters and authors, and sometimes the term violet is used and placed in between red and blue on the traditional color wheel. In a slightly different variation, on the [[HSV color space|color wheel]], purple is placed between magenta and violet. This shade is sometimes called electric purple (see [[shades of purple]]).<ref>Lanier F. (editor) ''The Rainbow Book'' Berkeley, California: Shambhala Publications and The Fine Arts Museums of San Francisco (1976) (Handbook for the Summer 1976 exhibition ''The Rainbow Art Show'' which took place primarily at the [[De Young Museum]] but also at other museums) Portfolio of color wheels by famous theoreticians—see Rood color wheel (1879) p. 93</ref>

In the [[RGB color model]], named for the colors red, green, and blue, used to create all the colors on a computer screen or television, the range of purples is created by mixing red and blue light of different intensities on a black screen. The standard [[HTML]] color purple is created by red and blue light of equal intensity, at a brightness that is between full power and darkness.

In color printing, purple is sometimes represented by the color [[magenta]] mixed with cyan and/or black, or sometimes by mixing magenta with red or blue. It can also be created by mixing just red and blue alone, but in that case the purple is less bright, with lower
saturation or intensity.  A less bright purple can also be created with light or paint by adding a certain quantity of the third primary color (green for light or yellow for pigment).

=== Relationship with violet ===
[[File:Line_of_purples.png|thumb|This [[CIE chromaticity diagram]] highlights the [[line of purples]] at its base, running from the violet corner near the left to the red corner at the right.]]
Purple is closely associated with [[Violet (color)|violet]]. In common usage, both refer to a variety of colors between blue and red in [[hue]].<ref name="Computational evidence of first ext3">{{cite journal |last1=Tager |first1=A. |last2=Kirchner |first2=E. |last3=Fedorovskaya |first3=E. |date=2021 |title=Computational evidence of first extensive usage of violet in the 1860s |journal=Color Research & Application |volume=46 |issue=5 |pages=961–977 |doi=10.1002/col.22638 |s2cid=233671776}}</ref><ref name="Color - the secret influence2">{{cite book |last1=Fehrman |first1=K.R. |title=Color - the secret influence |last2=Fehrman |first2=C. |date=2004 |publisher=Pearson Education |location=Upper Saddle River}}</ref><ref name=":33">{{cite journal |last1=Matschi |first1=M. |date=2005 |title=Color terms in English: Onomasiological and Semasiological aspects |journal=Onomasiology Online |volume=5 |pages=56–139}}</ref> Historically, purple has tended to be used for redder hues and violet for bluer hues.<ref name="Computational evidence of first ext3" /><ref name=":04">{{Cite web |title=violet, n.1 |url=https://www.oed.com/view/Entry/223648 |access-date=2020-04-06 |website=OED Online |publisher=Oxford University Press}}</ref><ref name=":14">{{Cite web |title=Violet |url=https://unabridged.merriam-webster.com/unabridged/violet |access-date=2020-04-06 |website=Webster's Third New International Dictionary, Unabridged}}</ref> In [[optics]], violet is a [[spectral color]]; it refers to the color of any different single wavelength of light on the short wavelength end of the visible spectrum, between approximately 380 and 450 nanometers,<ref name=":222">{{cite web |author=Georgia State University Department of Physics and Astronomy |title=Spectral Colors |url=http://hyperphysics.phy-astr.gsu.edu/hbase/vision/specol.html |access-date=20 October 2017 |website=HyperPhysics site}}</ref> whereas purple is the color of various combinations of red, blue, and violet light,<ref name="gilbert222">{{cite book |author=P. U.P. A Gilbert and Willy Haeberli |url=https://books.google.com/books?id=qSRqXvZ67lQC&pg=PA112 |title=Physics in the Arts |publisher=Academic Press |year=2008 |isbn=978-0-12-374150-9 |page=112}}</ref><ref name=":33" /> some of which humans perceive as similar to violet.

On a [[chromaticity diagram]], the straight line connecting the extreme spectral colors (red and violet) is known as the [[line of purples]] (or 'purple boundary'); it represents one limit of human [[Color vision|color perception]]. The color magenta used in the [[CMYK]] printing process is near the center of the line of purples, but most people associate the term "purple" with a somewhat bluer tone, such as is displayed by the color "electric purple" (a color also directly on the line of purples), shown below.

On the [[CIE 1931 color space|CIE xy chromaticity diagram]], violet is on the curved edge in the lower left, while purples are on the straight line connecting the extreme colors red and violet; this line is known as the [[line of purples]], or the purple line.<ref>{{cite book|title = Digital video and HDTV|author = Charles A. Poynton|publisher = Morgan Kaufmann|year = 2003|isbn = 1-55860-792-7|url = https://books.google.com/books?id=ra1lcAwgvq4C&pg=RA1-PA221}}</ref><ref>{{cite book|title = Handbook of Optoelectronics|author = John Dakin and Robert G. W. Brown|publisher = CRC Press|year = 2006|isbn = 0-7503-0646-7|url = https://books.google.com/books?id=fY98hmhWp58C&pg=PA381}}</ref>
{{Clear}}
<gallery mode="packed" heights="200px">
File:RGB illumination.jpg|On a computer or television screen, purple colors are created by mixing red and blue light. This is called the [[RGB color model]].
File:CIExy1931.png|The [[CIE 1931 color space|CIE xy chromaticity diagram]]
</gallery>

=== Pigments ===
*[[Hematite]] and [[manganese]] are the oldest pigments used for the color purple. They were used by [[Neolithic]] artists in the form of sticks, like charcoal, or ground and powdered and mixed with fat, and used as a paint. Hematite is a reddish [[iron oxide]] which, when ground coarsely, makes a purple pigment. One such pigment is [[caput mortuum (pigment)|caput mortuum]], whose name is also used in reference to [[mummy brown]]. The latter is another pigment containing hematite and historically produced with the use of mummified corpses.<ref>{{cite web|url=https://www.youtube.com/watch?v=rApTzWboLrA |archive-url=https://ghostarchive.org/varchive/youtube/20211211/rApTzWboLrA| archive-date=2021-12-11 |url-status=live|title=The Library of Rare Colors|last=Tom|first=Scott|date=18 March 2019|access-date=8 May 2019|via=YouTube}}{{cbignore}}</ref> Some of its compositions produce a purple color and may be called "mummy violet".<ref>{{cite web| title =Mummy Brown| publisher =naturalpigments.com| url =http://www.naturalpigments.com/detail.asp?PRODUCT_ID=460-22S| access-date =2008-02-08| archive-url =https://web.archive.org/web/20040816025813/http://www.naturalpigments.com/detail.asp?PRODUCT_ID=460-22S| archive-date =2004-08-16}}</ref> Manganese was also used in Roman times to color glass purple.<ref>Anne Varichon, ''Couleurs-pigments et teintures dans les mains des peuples'', p. 146</ref>
*[[Han purple]] was the first synthetic purple pigment, invented in China in about 700 BC. It was used in wall paintings and pottery and other applications.  In color, it was very close to [[indigo]], which had a similar chemical structure.  Han purple was very unstable, and sometimes was the result of the chemical breakdown of Han blue.

During the Middle Ages, artists usually made purple by combining red and blue pigments; most often blue azurite or lapis-lazuli with [[red ochre]], [[cinnabar]], or [[Minium (pigment)|minium]]. They also combined lake colors made by mixing dye with powder; using [[woad]] or indigo dye for the blue, and dye made from [[cochineal]] for the red.<ref name="Anne Carichon 2000 p.&nbsp;133" />

*[[Cobalt violet]] was the first modern synthetic color in the purple family, manufactured in 1859. It was found, along with [[cobalt blue]], in the palette of [[Claude Monet]], [[Paul Signac]], and [[Georges Seurat]]. It was stable, but had low tinting power and was expensive, so quickly went out of use.<ref>Isabelle Roelofs, ''La Couleur Expliquée aux artistes, 52–53.''</ref>
*[[Manganese violet]] was a stronger color than cobalt violet, and replaced it on the market.
*[[Quinacridone]] violet, one of a modern synthetic organic family of colors, was discovered in 1896 but not marketed until 1955.  It is sold today under a number of brand names.
<gallery mode="packed" heights="200px">
File:Lascaux painting.jpg|[[Manganese]] pigments were used in the [[neolithic]] paintings in the [[Lascaux cave]], France.
File:Hematite.jpg|[[Hematite]] was often used as the red-purple color in the cave paintings of [[Neolithic]] artists.
File:Purpurite-120161.jpg|A sample of [[purpurite]], or manganese phosphate, from the Packrat Mine in Southern California.
File:Cobaltviolet.jpg|A swatch of cobalt violet, popular among the French [[impressionists]].
File:Manganese violet.jpg|[[Manganese violet]] is a synthetic pigment invented in the mid-19th century.
File:CI Pigment Violet 19 Beta.JPG|[[Quinacridone]] violet, a synthetic organic pigment sold under many different names.
</gallery>

=== Dyes ===
The most famous purple dye in the ancient world was [[Tyrian purple]], made from a type of sea snail called the [[murex]], found around the Mediterranean. (See history section above).<ref name="StClair" />

In western [[Polynesia]], residents of the islands made a purple dye similar to Tyrian purple from the [[sea urchin]]. In Central America, the inhabitants made a dye from a different sea snail, the [[Purpura (gastropod)|purpura]], found on the coasts of [[Costa Rica]] and [[Nicaragua]]. The [[Mayans]] used this color to dye fabric for religious ceremonies, while the [[Aztecs]] used it for paintings of ideograms, where it symbolized royalty.<ref name="Anne Carichon 2000 p.&nbsp;133">Anne Carichon (2000), ''Couleurs: pigments et teintures dans les mains des peuples''. p.&nbsp;133.</ref>

In the Middle Ages, those who worked with blue and black dyes belonged to separate guilds from those who worked with red and yellow dyes, and were often forbidden to dye any other colors than those of their own guild.<ref name="StClair2">{{Cite book|title=The Secret Lives of Colour|last=St. Clair|first=Kassia|publisher=John Murray|year=2016|isbn=978-1-4736-3081-9|location=London|page=211|oclc=936144129}}</ref> Most purple fabric was made by the dyers who worked with red, and who used dye from [[Rubia|madder]] or [[cochineal]], so medieval violet colors were inclined toward red.<ref>{{Cite web |last=Clayton |first=Graham |date=2016-03-23 |title=What colour are you? A focus on Purple and Violet |url=https://sdc.org.uk/what-colour-are-you-a-focus-on-purple-and-violet/ |access-date=2024-05-01 |website=SDC |language=en-GB}}</ref>

[[Orcein]], or ''purple moss'', was another common purple dye. It was known to the ancient Greeks and Hebrews, and was made from a Mediterranean [[lichen]] called archil or dyer's moss ([[Roccella tinctoria]]), combined with an [[ammoniac]], usually urine. Orcein began to achieve popularity again in the 19th century, when violet and purple became the color of demi-mourning, worn after a widow or widower had worn black for a certain time, before he or she returned to wearing ordinary colors.<ref>Anne Carichon (2000), ''Couleurs: pigments et teintures dans les mains des peuples''. p.&nbsp;144.</ref>

From the Middle Ages onward, purple dyes for the clothing of common people were often made from the [[blackberry]] or other red fruit of the genus [[rubus]], or from the [[mulberry]]. All of these dyes were more reddish than bluish, and faded easily with washing and exposure to sunlight.

A popular new dye which arrived in Europe from the New World during the Renaissance was made from the wood of the [[logwood]] tree (H''aematoxylum campechianum''), which grew in Spanish Mexico. Depending on the different minerals added to the dye, it produced a blue, red, black or, with the addition of [[alum]], a purple color, it made a good color, but, like earlier dyes, it did not resist sunlight or washing.

In the 18th century, chemists in England, France and Germany began to create the first synthetic dyes. Two synthetic purple dyes were invented at about the same time. '''Cudbear''' is a [[dye]] extracted from [[orchil]] [[lichen]]s that can be used to dye [[wool]] and [[silk]], without the use of [[mordant]]. Cudbear was developed by Dr Cuthbert Gordon of [[Scotland]]: production began in 1758, The lichen is first boiled in a solution of [[ammonium carbonate]]. The mixture is then cooled and [[ammonia]] is added and the mixture is kept damp for 3–4 weeks. Then the lichen is dried and ground to powder. The manufacture details were carefully protected, with a ten-feet high wall being built around the manufacturing facility, and staff consisting of Highlanders sworn to secrecy.

'''French purple''' was developed in France at about the same time. The lichen is extracted by urine or ammonia. Then the extract is acidified, the dissolved dye precipitates and is washed. Then it is dissolved in ammonia again, the solution is heated in air until it becomes purple, then it is precipitated with [[calcium chloride]]; the resulting dye was more solid and stable than other purples.

'''Cobalt violet''' is a synthetic pigment that was invented in the second half of the 19th century, and is made by a similar process as [[cobalt blue]], [[cerulean blue]]  and [[cobalt green]]. It is the violet pigment most commonly used today by artists. In spite of its name, this pigment produces a purple rather than violet color.<ref name="Computational evidence of first ext"/>

'''[[Mauveine]]''', also known as '''[[aniline]] purple''' and '''Perkin's [[mauve]]''', was the first synthetic [[organic chemistry|organic chemical]] [[dye]],<ref>{{cite journal
| title=  History: 150 Years of mauveine
| author= Hubner K
| journal=  Chemie in unserer Zeit
| year=  2006
| volume=  40
| issue=  4
| pages= 274–275
| doi= 10.1002/ciuz.200690054 }}</ref><ref>{{cite journal
| title=  Perkin's Mauve: Ancestor of the Organic Chemical Industry
| author= Anthony S. Travis
| journal=  Technology and Culture
| year=  1990
| volume=  31
| issue=  1
| pages= 51–82
| doi=  10.2307/3105760
| jstor=3105760
| s2cid= 112031120
}}</ref> discovered [[serendipity|serendipitously]] in 1856.

Its chemical name is 3-amino-2,±9-dimethyl-5-phenyl-7-(p-tolylamino)phenazinium acetate.

[[Fuchsine]] was another synthetic dye made shortly after mauveine.  It produced a brilliant fuchsia color.

In the 1950s, a new family of purple and violet synthetic organic pigments called [[quinacridone]] came onto the market. It had originally been discovered in 1896, but were not synthesized until 1936, and not manufactured until the 1950s. The colors in the group range from deep red to bluish purple in color, and have the molecular formula C<sub>20</sub>H<sub>12</sub>N<sub>2</sub>O<sub>2</sub>. They have strong resistance to sunlight and washing, and are widely used today in oil paints, water colors, and acrylics, as well as in automobile coatings and other industrial coatings.
<gallery mode="packed" heights="200px">
File:Black Butte blackberry.jpg|[[Blackberry|Blackberries]] were sometimes used to make purple dye in the Middle Ages.
File:A lichen - Ochrolechia tartarea - geograph.org.uk - 995354.jpg|This lichen, growing on a tree in Scotland, was used in the 18th century to make a common purple dye called Cudbear.
File:Mauv2.jpg|A sample of silk dyed with the original mauveine dye.
File:Basic Fuchsine in aqueous solution.jpg|A sample of [[fuchsine]] dye
</gallery>

=== Animals ===
<gallery mode="packed" heights="200px">
File:Cinnyricinclus_leucogaster_-_20080321.jpg|The male [[violet-backed starling]] sports a very bright, iridescent purple plumage.
File:Nasikabatrachus sahyadrensis.jpg|The [[purple frog]] is a species of [[amphibian]] found in India.
File:Pseudanthias pascalus.jpg|''Pseudanthias pascalus'' or purple queenfish.
File:PurpleUrchinPuertoVG.JPG|The [[Strongylocentrotus purpuratus|purple sea urchin]] from Mexico.
File:Purple Heron in flight.jpg|A [[purple heron]] in flight (South Africa).
File:Carpodacus purpureus CT3.jpg|A [[purple finch]] (North America).
File:Lorius domicella -Jurong Bird Park -upper body-8a.jpg|The ''[[Lorius domicella]]'', or purple-naped lory, from Indonesia.
</gallery>

=== Anthocyanins ===
Certain grapes, eggplants, pansies and other fruits, vegetables and flowers may appear purple due to the presence of natural pigments called [[anthocyanins]]. These pigments are found in the leaves, roots, stems, vegetables, fruits and flowers of all plants. They aid [[photosynthesis]] by blocking harmful wavelengths of light that would damage the leaves. In flowers, the purple anthocyanins help attract insects who pollinate the flowers. Not all anthocyanins are purple; they vary in color from red to purple to blue, green, or yellow, depending upon the level of their [[pH]].
<gallery mode="packed" heights="200">
File:Purplec.png|The purple colors of this [[cauliflower]], grapes, fruits, vegetables and flowers comes from natural pigments called [[anthocyanins]].
File:Indicateur chou rouge.jpg|Anthocyanins range in color from red to purple to green, blue and yellow, depending upon the level of their [[pH]].
File:Img fagus sylvatica atropurpurea 1890.jpg|Anthocyanins also account for the purple color in these [[Fagus sylvatica|copper beech]] trees, and in purple autumn leaves.
File:Blood orange sliced.jpg|Anthocyanins produce the purple color in blood oranges.
File:Purple pansy flower.jpg|alt=Purple pansy|A purple [[pansy]].
File:Blue Hydrangea (common names hydrangea or hortensia).jpg|alt="Blue" hydrangea is often actually purple.|"Blue" [[hydrangea]] is often actually purple.
</gallery>

=== Plants and flowers ===
*[[Stipa|Purple needlegrass]] is the [[state grass]] of California.
<gallery mode="packed" heights="200">
File:Artichoke in Dalat, Vietnam.jpg|An [[artichoke]] flower in blossom in Dalat, [[Vietnam]]
File:Iris germanica10.jpg|''[[Iris germanica]]'' flowers
File:Lilac blossom Fliederblüte Syringa vulgaris 05.jpg|''[[Syringa vulgaris]]'', or [[lilac]] blossoms
File:MEDICAGO SATIVA - APIS - IB-125.JPG|''[[Medicago sativa]]'', known as [[alfalfa]] in the U.S. and lucerne in the U.K.
File:Aster alpinus 002.JPG|The ''[[Aster alpinus]]'', or alpine aster, is native to the European mountains, including the [[Alps]], while a subspecies is found in [[Canada]] and the United States.
File:Single lavender flower02.jpg|[[Lavender]] flowers.
File:Purple Rose1.jpg|A purple [[rose]].
File:Wisteria floribunda5.jpg|alt=Wisteria is a pale purple color.|[[Wisteria]] is a pale purple color.
File:Purple_salsify_(7356683346).jpg|[[Tragopogon porrifolius|salsify]]
</gallery>

=== Microbiology ===
*[[Purple bacteria]] are [[bacteria]] that are [[phototroph]]ic, that is, capable of producing energy through [[photosynthesis]].<ref name=bryantfrigaard>{{cite journal
|author=D.A. Bryant & N.-U. Frigaard
|date=November 2006
|title=Prokaryotic photosynthesis and phototrophy illuminated
|journal=Trends Microbiol.
|volume=14
|issue=11
|pages=488–96
|doi=10.1016/j.tim.2006.09.001
|pmid=16997562
}}</ref>

*In April 2007, it was suggested that early [[archaea]] may have used [[retinal]], a purple pigment, instead of [[chlorophyll]], to extract energy from the sun. If so, large areas of the ocean and shoreline would have been colored purple; this is called the [[Purple Earth hypothesis]].<ref>{{cite web|url=http://www.livescience.com/environment/070410_purple_earth.html |title=Early Earth Was Purple, Study Suggests |publisher=Livescience.com |date=2007-04-10 |access-date=2012-12-29}}</ref>

=== Astronomy ===
* One of the [[star]]s in the [[Pleiades]], called [[Pleione (star)|Pleione]], is sometimes called ''Purple Pleione'' because, being a fast spinning star, it has a purple hue caused by its blue-white color being obscured by a spinning ring of electrically excited red [[hydrogen]] gas.<ref>Barnett, Lincoln and the editorial staff of Life ''The World We Live In'' New York:1955--Simon and Schuster--Page 284 There is also an illustration of Purple Pleione by the noted astronomical artist [[Chesley Bonestell]].</ref>
*The [[Purple Forbidden enclosure]] is a name used in traditional [[Chinese astronomy]] for those [[Chinese constellations]] that surround the [[north celestial pole]].

=== Geography ===
*[[Purple Mountain (Nanjing)|Purple Mountain]] is located on the eastern side of [[Nanjing]]. Its peaks are often found enveloped in purple clouds at dawn and dusk, hence comes its name "Purple Mountain". The [[Purple Mountain Observatory]] is located there.
*[[Purple Mountain, County Kerry|Purple Mountain]] in County Kerry, Ireland, takes its name from the color of the shivered slate on its summit.
*[[Purple Mountain (Wyoming)|Purple Mountain]] in [[Wyoming]] (el. {{convert|8392|ft|m}}) is a mountain peak in the southern section of the [[Gallatin Range]] in [[Yellowstone National Park]].
*Purple Mountain, Alaska
*Purple Mountain, Oregon
*Purple Mountain, Washington
*Purple Peak, Colorado
<gallery mode="packed" heights="200px">
File:Purple Mountain View, Killarney.jpg|[[Purple Mountain, County Kerry|Purple Mountain]] near Killarney, Ireland.
File:PurpleMountainYNP2010.jpg|[[Purple Mountain (Wyoming)|Purple Mountain]] in [[Yellowstone National Park]].
File:PurpleMountain01.JPG|[[Purple Mountain (Nanjing)|Purple Mountain]], Nanjing.
</gallery>

=== Purple mountains phenomenon ===

It has been observed that the greater the distance between a viewers eyes and mountains, the lighter and more blue or purple they will appear. This phenomenon, long recognized by [[Leonardo da Vinci]] and other painters, is called [[aerial perspective]] or atmospheric perspective. The more distant the mountains are, the less contrast the eye sees between the mountains and the sky.

The bluish color is caused by an optical effect called [[Rayleigh scattering]]. The sunlit sky is blue because [[air]] scatters short-[[wavelength]] light more than longer wavelengths. Since blue light is at the short wavelength end of the visible spectrum, it is more strongly scattered in the atmosphere than long wavelength red light. The result is that the human eye perceives blue when looking toward parts of the sky other than the sun.<ref>"[http://search.eb.com/eb/article-9062822 Rayleigh scattering] {{Webarchive|url=https://web.archive.org/web/20221031205802/https://academic.eb.com/ |date=2022-10-31 }}." ''Encyclopædia Britannica''. 2007. Encyclopædia Britannica Online. 16 Nov. 2007.</ref>

At sunrise and sunset, the light is passing through the atmosphere at a lower angle, and traveling a greater distance through a larger volume of air. Much of the green and blue is scattered away, and more red light comes to the eye, creating the colors of the sunrise and sunset and making the mountains look purple.

The phenomenon is referenced in the song "[[America the Beautiful]]", where the lyrics refer to "purple mountains' majesty" among other features of the United States landscape. A [[List of Crayola crayon colors|Crayola]] crayon called Purple Mountain Majesty in reference to the lyric was first formulated in 1993.
<gallery mode="packed" heights="200px">
File:Aerial perspective 1.JPG|The more distant mountains are, the lighter and more blue they are.  This is called atmospheric perspective or [[aerial perspective]].
File:Auke Bay Alaska 2.jpg|Sunset at [[Auke Bay]], [[Alaska]]. Thanks to [[Rayleigh scattering]], the mountains appear purple.
</gallery>