The colour Green is considered to be one of the major colours in the human perception of sight. What is seen as green is, scientifically, electromagnetic radiation with a wavelength of 487 to 570 nanometres. Wavelengths of electromagnetic radiation from 400 to 700 nm create the spectrum of colours as a whole. In the subtractive colour system of dyes and pigments, green is not one of the primary colours. Green is made by mixing the primary colour yellow with the primary colour blue or cyan. In the additive colour system of light, green is one of the primary colours along with red and blue. On the RYB colour wheel, the complement of green is red, whereas on the RGB colour wheel, the complement of green is magenta. Green is found throughout the natural world in animals, plants, and minerals. It also has significant value in most human cultures today and through history.
The modern English word green derived from the Old English grene or groeni. It is an adjective form of the verb growan, which means to grow or turn green, as in plant life. The languages of the Dutch, Danish, and German people of the time used similar words – groen, gron, and grun, respectively. The first use of the modern word green in the English language dates back to 700 AD.
Some Asian languages do not traditionally distinguish green from blue. However, most of these Asian languages have since added a word to correspond to green as used in the Western world. In some languages of the Middle-east, green can also mean dark, or dark-skinned.
When electromagnetic radiation with a wavelength between 487 and 570 nm reaches the human eye, it triggers the M cone cells in the eye and, to a lesser degree, the L cone cells. These cells send a signal to the brain that registers what most humans are taught is green. The human eye, when adapted to the dark, is most sensitive to green at a wavelength of 507 nm, which is more of a blue-green. When the eye is adapted to the light, it is most sensitive to green at a wavelength of 555 nm, which is more of a yellow-green.
When used as a primary colour in the additive colour system, the dominant wavelength of green is approximately 550 nm. The complete spectrum of colours can be created in this system by mixing together various amounts of green, red, and blue light. In the “unique” colour system, unique green, a green with no hint of yellow or blue hue, is created by mixing primary green with a slight amount of primary blue.
In the subtractive colour system, which incorporates traditional colour theory, green is created by mixing yellow and blue pigments.
Green in Minerals
Many minerals have a green hue. Some of these minerals are used in creating green pigments, and dyes. Pigments are defined as substances that reflect green wavelengths, in contrast to emitting them. The number of minerals coloured green is so vast, that it would be difficult to list them all. Among the most popular of green minerals is the emerald. Emeralds get their green colour by being composed of small amounts of chromium and vanadium. Chromium oxide is often used to create a pigment known as chrome green, institutional green, or viridian. Oxidized copper is also a mineral source of green pigment. These are known as malachite pigments. Early forms of green paints were made with mixtures of oxidized cobalt and zinc. In fireworks, various forms of barium salts are used to create green fire and sparks. Green flares, however, are made with potassium nitrate and boron.
Green in Biology
Green is one of the most common colours in biology because of chlorophyll. Chlorophyll is the complex chemical in plant life, which plays a large part in photosynthesis, the process of converting light into energy. Chlorophyll is what makes plants green. Because of the presence of green in nature, many animals have adapted to use the colour green for protection in the form of camouflage. Green species of animals exist in almost all types, primarily reptiles and amphibians. Other types of animals that can be green or use green are insects, fish, and birds.
Green in Human Culture
Green is apparent in many facets of human culture. It has been used throughout history and is still in use today symbolically for many reasons. Some of the most popular forms of symbolism associated with green are as follows:
Nature – The earliest adaptations of green as a symbol are for nature and attributes of life, such as fertility, birth, and rebirth. In Ancient Egypt green represented immortality. Today, green is used as a symbol for environmentalism. The move to be more conscious of the environment is called the green movement. Anything that has a positive effect of the environment or has a more positive effect than it traditionally had is called green.
Love – In medieval Europe, green was a symbol for love and the lustful desires of humans.
Jealousy – Green is often used as a symbol to represent jealousy or envy. This can be in conjunction with love or lustful desires, or it can be for material objects, wealth, or status.
Evil – Green has had an association with evil and devilry in some cultures. Imps, faeries, demons, and other evil spirits are often depicted as green. Old Celts would avoid wearing green clothes because they were thought to bring death or other misfortune. Many British believe green to be unlucky.
Prosperity – In the United States and other parts of the world where U.S. money is common, green represents wealth because all paper currency in the U.S. uses green ink. It can also be associated with prosperity due to the colour of emeralds.
Green in Politics and Religion
Flags and symbols of many countries around the world incorporate green. It is especially predominant in Africa, west Asia, and Central and South America. In many cases, it is used to represent natural richness.
Green is also the primary colour traditionally associated with Islam. Muhammad is quoted in the Quran as associating green with goodness. Green is also used by several sects of Christianity, including Roman Catholicism, Eastern Orthodoxy, and Protestantism. Green has traditionally been used in Christmas celebrations through the use of evergreen trees, branches, and holly.