Description

Blue Wallpapers is the wallpaper colourbetweenviolet and green on the optical spectrum of visible light.Humaneyes perceive blue when observing light with a wavelengthbetween450 and 495 nanometres, which is between 4500 and 4950ångströms.Blues with a higher frequency and thus a shorterwavelengthgradually look more violet, while those with a lowerfrequency and alonger wavelength gradually appear more green. Pureblue, in themiddle, has a wavelength of 470 nanometers (4700ångströms). Inpainting and traditional colour theory, blue is oneof the threeprimary colours of pigments, along with red andyellow, which can bemixed to form a wide gamut of colours. Red andblue mixed togetherform violet, blue and yellow together formgreen. Blue is also aprimary colour in the RGB colour model, usedto create all thecolours on the screen of a television or computermonitor.

The modern English word blue comes from Middle English bleuorblewe, from the Old French bleu, a word of Germanic originrelatedto Old Dutch, Old High German, Old Saxon blāo and OldFrisian blāw,blau. The clear sky and the deep sea appear bluebecause of anoptical effect known as Rayleigh scattering. Whensunlight passesthrough the atmosphere, the blue wavelengths arescattered morewidely by the oxygen and nitrogen molecules, and moreblue comes toour eyes. An optical effect called Tyndall scattering,similar toRayleigh scattering, explains blue eyes; there is no bluepigmentin blue eyes. Distant objects appear more blue because ofanotheroptical effect called atmospheric perspective.

Blue has been used for art and decoration since ancient times.Thesemi-precious stone lapis lazuli, coming from mines inAfghanistan,was used in ancient Egypt for jewelry and ornament andlater, inThe Renaissance, to make the pigment ultramarine, themostexpensive of all pigments. It is the most important colorinJudaism. In the Middle Ages, cobalt blue was used to colourthestained glass windows of cathedrals. Beginning in the 9thcentury,Chinese artists used cobalt to make fine blue and whiteporcelain.Blue dyes for clothing were made from woad in Europe andindigo inAsia and Africa. In 1828 a synthetic ultramarine pigmentwasdeveloped, and synthetic blue dyes and pigments graduallyreplacedmineral pigments and vegetable dyes. Pierre-Auguste Renoir,Vincentvan Gogh and other late 19th century painters usedultramarine andcobalt blue not just to depict nature, but to createmoods andemotions. In the late 18th century and 19th century, bluebecame apopular colour for military uniforms and police uniforms.In the20th century, because blue was commonly associated withharmony, itwas chosen as the colour of the flags of the UnitedNations and theEuropean Union. Toward the end of the 20th century,dark bluereplaced dark grey as the most common colour for businesssuits;surveys showed that blue was the colour most associated withthemasculine, just ahead of black, and was also the colourmostassociated with intelligence, knowledge, calmandconcentration.