BLUE

Blue is a colour, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 440–490 nm. It is considered one of the additive primary colours. On the HSV Colour Wheel, the complement of blue is yellow; that is, a colour corresponding to an equal mixture of red and green light. On a colour wheel based on traditional colour theory (RYB), the complementary colour to blue is considered to be orange (based on the Munsell colour wheel).[2] The English language commonly uses "blue" to refer to any colour from navy blue to cyan. The word itself is derived from the Old French word bleu.

Etymology and definitions

Blueberries

The modern English word blue comes from the Middle English, bleu or blwe, which came from an Old French word bleu of Germanic origin (Frankish or possibly Old High German blao, "shining"). Bleu replaced Old English blaw. The root of these variations was the Proto-Germanic blæwaz, which was also the root of the Old Norse word bla and the modern Icelandic blár, and the Scandinavian word blå, but it can refer to other non blue colours. A Scots and Scottish English word for "blue-grey" is blae, from the Middle English bla ("dark blue," from the Old English blæd). Ancient Greek lacked a word for blue and Homer called the colour of the sea "wine dark", except that the word kyanos (cyan) was used for dark blue enamel.

As a curiosity, blue is thought to be cognate with blond, blank and black through the Germanic word. Through a Proto-Indo-European root, it is also linked with Latin flavus ("yellow"; see flavescent and flavine), with Greek phalos (white), French blanc (white, blank) (borrowed from Old Frankish), and with Russian белый, belyi ("white," see beluga), and Welsh blawr (grey) all of which derive (according to the American Heritage Dictionary) from the Proto-Indo-European root *bhel- meaning "to shine, flash or burn", (more specifically the word bhle-was, which meant light coloured, blue, blond, or yellow), whence came the names of various bright colours, and that of colour black from a derivation meaning "burnt" (other words derived from the root *bhel- include bleach, bleak, blind, blink, blank, blush, blaze, flame, fulminate, flagrant and phlegm).

In the English language, blue may refer to the feeling of sadness. "He was feeling blue". This is because blue was related to rain, or storms, and in Greek mythology, the god Zeus would make rain when he was sad (crying), and a storm when he was angry. Kyanos was a name used in Ancient Greek to refer to dark blue tile (in English it means blue-green or cyan).[3] The phrase "feeling blue" is linked also to a custom among many old deepwater sailing ships. If the ship lost the captain or any of the officers during its voyage, she would fly blue flags and have a blue band painted along her entire hull when returning to home port.[4]

Many languages do not have separate terms for blue and or green, instead using a cover term for both (when the issue is discussed in linguistics, this cover term is sometimes called grue in English).

[edit] In science
The sky and water often appear blue

[edit] Pigments

Traditionally, blue has been considered a primary colour in painting, with the secondary colour orange as its complement.

Blue pigments include azurite (Cu3(CO3)2(OH)2), ultramarine (Na8-10Al6Si6O24S2-4), cerulean blue (primarily cobalt (II) stanate: Co2SnO4), cobalt blue (cobalt(II) aluminate: CoAl2O4), and Prussian blue (milori blue: primarily Fe7(CN)18).

[edit] Scientific natural standards for blue

* Emission spectrum of Cu2+
* Electronic spectrum of aqua-ions Cu(H2O)52+

[edit] Animals
Blue Jay

* When an animal's coat is described as "blue", it usually refers to a shade of grey that takes on a bluish tint, a diluted variant of a pure black coat.[citation needed] This designation is used for a variety of animals, including dog coats, some rat coats, cat coats, some chicken breeds, and some horse coat colours.