Piraeus is a port city in the region of Attica, Greece. Piraeus is located within the Athens urban area, 12 kilometres southwest from its city centre, lies along the east coast of the Saronic Gulf. According to the 2011 census, Piraeus had a population of 163,688 people within its administrative limits, making it the fourth largest municipality in Greece and the second largest within the urban area of the Greek capital, following the municipality of Athens; the municipality of Piraeus and several other suburban municipalities within the regional unit of Piraeus form the greater Piraeus area, with a total population of 448,997. Piraeus has a long recorded history, dating to ancient Greece; the city was developed in the early 5th century BC, when it was selected to serve as the port city of classical Athens and was transformed into a prototype harbour, concentrating all the import and transit trade of Athens. During the Golden Age of Athens the Long Walls were constructed to fortify its port, it became the chief harbour of ancient Greece, but declined after the 4th century AD, growing once more in the 19th century, after Athens' declaration as the capital of Greece.
In the modern era, Piraeus is a large city, bustling with activity and an integral part of Athens, acting as home to the country's biggest harbour and bearing all the characteristics of a huge marine and commercial-industrial centre. The port of Piraeus is the chief port in Greece, the largest passenger port in Europe and the second largest in the world, servicing about 20 million passengers annually. With a throughput of 1.4 million TEUs, Piraeus is placed among the top ten ports in container traffic in Europe and the top container port in the Eastern Mediterranean. The city hosted events in both the 1896 and 2004 Summer Olympics held in Athens; the University of Piraeus is one of the largest universities in Greece. Piraeus, which means'the place over the passage', has been inhabited since the 26th century BC. In prehistoric times, Piraeus was a rocky island consisting of the steep hill of Munichia, modern-day Kastella, was connected to the mainland by a low-lying stretch of land, flooded with sea water most of the year, used as a salt field whenever it dried up.
It was called the Halipedon, meaning the'salt field', its muddy soil made it a tricky passage. Through the centuries, the area was silted and flooding ceased, thus by early classical times the land passage was made safe. In ancient Greece, Piraeus assumed its importance with its three deep water harbours, the main port of Cantharus and the two smaller of Zea and Munichia, replaced the older and shallow Phaleron harbour, which fell into disuse. In the late 6th century BC, the area caught attention due to its advantages. In 511 BC, the hill of Munichia was fortified by Hippias and four years Piraeus became a deme of Athens by Cleisthenes. According to the ancient Greek historian Thucydides, in 493 BC, Themistocles initiated the fortification works in Piraeus and advised the Athenians to take advantage of its natural harbours' strategic potential instead of using the sandy bay of Phaleron. In 483 BC, a new silver vein was discovered in Laurion mines, utilized to fund the construction of 200 triremes, the Athenian fleet, transferred to Piraeus and was built in its shipyards.
The Athenian fleet played a crucial role in the battle of Salamis against the Persians in 480 BC. From on Piraeus was permanently used as the navy base. After the second Persian invasion of Greece, Themistocles fortified the three harbours of Piraeus and created the neosoikoi; the city's fortification was farther reinforced by the construction of the Long Walls under Cimon and Pericles, with which secure port's route to Athens main city. Meanwhile, Piraeus was rebuilt to the famous grid plan of architect Hippodamus of Miletus, known as the Hippodamian plan, the main agora of the city was named after him in honour; as a result, Piraeus flourished and became a port of high security and great commercial activity, a city bustling with life. During the Peloponnesian War, Piraeus suffered its first setback. In the second year of the war, the first cases of the Athens plague were recorded in Piraeus. In 429 the Spartans ravaged Salamis as part of an abortive attack on the Piraeus, when the Athenians responded by sending a fleet to investigate, the Spartan alliance forces fled.
In 404 BC, the Spartan fleet under Lysander blockaded Piraeus and subsequently Athens surrendered to the Spartans, putting an end to the Delian League and the war itself. Piraeus would follow the fate of Athens and was to bear the brunt of the Spartans' rage, as the city's walls and the Long Walls were torn down; as a result, the tattered and unfortified port city was not able to compete with prosperous Rhodes, which controlled commerce. In 403 BC, Munichia was seized by Thrasybulus and the exiles from Phyle, in the battle of Munichia, where the Phyleans defeated the Thirty Tyrants of Athens, but in the following battle of Piraeus the exiles were defeated by Spartan forces. After the reinstatement of democracy, Conon rebuilt the walls in 393 BC, founded the temple of Aphrodite Euploia and the sanctuary of Zeus Sotiros and Athena, built the famous Skeuotheke of Philon, the ruins of which have been discovered at Zea harbour; the reconstruction of Piraeus went on
A paramilitary is a semi-militarized force whose organizational structure, training and function are similar to those of a professional military, but, formally not part of a government's armed forces. Under the law of war, a state may incorporate a paramilitary organization or armed agency into its combatant armed forces; the other parties to a conflict have to be notified thereof. Though a paramilitary is not a military force, it is equivalent to a military's light infantry force in terms of intensity and organizational structure. A paramilitary may commonly fall under the command of a military despite not being part of the military or play an assisting role for the military in times of war. Depending on the definition adopted, "paramilitaries" may include: Irregular military forces: militias, insurgents, etc; the auxiliary forces of a state's military: national guard, presidential guard, republican guard, state defense force, home guard, royal guard, imperial guard Some police forces or auxiliary police: Indonesia's Mobile Brigade Corps, Detachment 88, India's Assam Rifles, Central Reserve Police Force, Border Security Force, etc.
Semi-militarized law enforcement personnel within normal police forces, such as SWAT teams in the United States and a number of other countries Gendarmeries, such as Egyptian Central Security Forces and Russia's National Guard Border guards, such as Russia's Border Guard Service, Australian Border Force, India's Border Security Force The United States' Federal Protective Forces Security forces of ambiguous military status: internal troops, railroad guards, or railway troops Volunteer Defence Corps, such as Volunteer Defence Corps in Thailand, Volunteer Defence Corps in Australia, Shanghai Volunteer Corps, Royal Hong Kong Regiment The fire departments of many countries and locales, although unarmed, are organized in a manner similar to military or police forces. List of paramilitary organizations List of defunct paramilitary organizations Category:Rebel militia groups Weimar paramilitary groups List of Serbian paramilitary formations Militarization of police Panamanian Public Forces Fourth-generation warfare Private army Private Military Companies Death squad Violent non-state actor List of countries by number of military and paramilitary personnel Golkar, Saeid.
Paramilitarization of the Economy: the Case of Iran's Basij Militia, Armed Forces & Society, Vol. 38, No. 4 Golkar, Saeid.. Organization of the Oppressed or Organization for Oppressing: Analysing the Role of the Basij Militia of Iran. Politics, Religion & Ideology, Dec. 37–41. Doi:10.1080/21567689.2012.725661 Mexico's Plan to Create a Paramilitary Force Global Security
A buoy is a floating device that can have many purposes. It can be allowed to drift with ocean currents; the etymology of the word is disputed. Buoy racing is the most prevalent form of yacht racing Emergency wreck buoy – An Emergency Wreck Buoys provides a clear and unambiguous means of marking new wrecks; this buoy is used as a temporary response for the first 24–72 hours. This buoy is coloured in an equal number of blue and yellow vertical stripes and is fitted with an alternating blue and yellow flashing light; this has come about due to the collisions which occurred in the Dover Straits in 2002 when vessels struck the new wreck of the MV Tricolor. Ice marking buoys – used for marking ice holes in frozen lakes and rivers, so that snowmobiles do not drive over the holes. Large Navigational Buoy is an automatic buoy over 10m high equipped with a powerful light monitored electronically as a replacement for lightships. A LNB may be marked on charts as a "Superbuoy." Lobster trap buoys – brightly colored buoys used for the marking of lobster trap locations so the person lobster fishing can find their lobster traps.
Each lobster fisherman has his or her own color markings or registration numbers so they know which ones are theirs. They are only allowed to haul their own traps and must display their buoy color or license number on their boat so law enforcement officials know what they should be hauling; the buoys are brightly colored with visible numbers so they can be seen under conditions when there is poor visibility like rain, sea smoke, etc. lateral marker buoy Safe water mark or Fairway Buoy – a navigational buoy which marks the entrance to a channel or a nearby landfall Sea mark – aids pilotage by marking a maritime channel and administrative area to allow boats and ships to navigate safely. Some navigational buoys are fitted with a bell or gong, which sounds when waves move the buoy Wreck buoy – a buoy to mark a wrecked ship to warn other ships to keep away because of unseen hazards. Lifebuoy – used as a life saving buoy designed to be thrown to a person in the water to provide buoyancy. Has a connecting line allowing the casualty to be pulled to the rescuer Self-locating datum marker buoy – A 70% scale Coastal Ocean Dynamics Experiment /Davis-style oceanographic surface drifter with drogue vanes between 30 and 100 cm deep.
This particular surface drifter is designed for deployment from a U. S. Coast Guard vessel or airframe for search and rescue. Since the SLDMB has a small surface area above the ocean surface and a high underwater surface area, there is little leeway in response to the direct forcing of winds and waves. Submarine rescue buoy – used for release in case of emergencies or for communication Decompression buoy – deployed by submerged scuba divers to mark their position underwater whilst doing decompression stops Shot buoy – used to mark dive sites for the boat safety cover of scuba divers so that the divers can descend to the dive site more in conditions of low visibility or tidal currents and more safely do decompression stops on their ascent. Surface marker buoy – taken on dives by scuba divers to mark their position underwater Profiling buoy – specialized models which adjust buoyancy so that they will sink at a controlled rate to 2,000 metres below the surface while measuring sea temperatures and salinity.
After a time 10 days, the buoy returns to the surface, transmits its data via satellite, sinks again. See Argo. Tsunami buoys – anchored buoys that can detect sudden changes in undersea water pressure are used as part of tsunami warning systems in the Pacific Tsunami Warning Center and Indian Oceans. Wave buoy – used to measure the movement of the water surface as a wave train; the wave train is analysed to determine statistics like the significant wave height and period, wave direction. Weather buoys – equipped to measure weather parameters such as air temperature, barometric pressure, wind speed and direction and to report these data via satellite radio links such as the purpose-built Argos System or commercial satellite phone networks to meteorological centres for use in forecasting and climate study. May be allowed to drift in the open ocean currents. Position is calculated by the satellite. Weather buoys are sometimes referred to as ODAS buoys or Ocean Data Acquisition Systems and may be marked on charts as "Superbuoys."
Mooring buoys – used to keep one end of a mooring cable or chain on the water's surface so that ships or boats can tie on to it. Many marinas mark these with a number and assign it to a particular vessel, or rent it out to transient vessels. Tripping buoys – used to keep one end of a'tripping line' on the water's surface so that a stuck anchor can more be freed Marker buoys – used in naval warfare anti-submarine warfare, is a light-emitting or smoke-emitting, or both, marker using some kind of pyrotechnic to provide the flare and smoke, it is a 3-inch diameter device about 20 inches long, set off by contact with seawater and floats on the surface. Some markers extinguish after others are made to sink. Sonobuoy – used by anti-submarine warfare aircraft to detect submarines by SONAR Target buoy – used to simulate target in live fire exercise by naval and coastal forces targeted by weapons like HMG's, rapid fire cannons and anti-tank rockets. DAN buoy – has several meanings: A large maritime navigational aid providing a platform for light and radio beacons A lifebuoy with flags used on yachts and smaller pl
Gold called golden, is a color. The web color gold is sometimes referred to as golden to distinguish it from the color metallic gold; the use of gold as a color term in traditional usage is more applied to the color "metallic gold". The first recorded use of golden as a color name in English was in 1300 to refer to the element gold and in 1423 to refer to blond hair. Metallic gold, such as in paint, is called goldtone or gold tone. In heraldry, the French word or is used. In model building, the color gold is different from brass. A shiny or metallic silvertone object can be painted with transparent yellow to obtain goldtone, something done with Christmas decorations. At right is displayed a representation of the color metallic gold, a simulation of the color of the actual metallic element gold itself—gold shade; the source of this color is the ISCC-NBS Dictionary of Color Names, a color dictionary used by stamp collectors to identify the colors of stamps—See color sample of the color Gold displayed on indicated web page:The first recorded use of gold as a color name in English was in the year 1400.
The American Heritage Dictionary defines the color metallic gold as "A light olive-brown to dark yellow, or a moderate, strong to vivid yellow." Of course, the visual sensation associated with the metal gold is its metallic shine. This cannot be reproduced by a simple solid color, because the shiny effect is due to the material's reflective brightness varying with the surface's angle to the light source; this is. In sacral art in Christian churches, real gold was used for rendering gold in paintings, e.g. for the halo of saints. Gold can be woven into sheets of silk to give an East Asian traditional look. More recent art styles, e.g. art nouveau made use of a metallic, shining gold. Old gold is a dark yellow, which varies from heavy olive brown to deep or strong yellow; the accepted color old gold is on the darker rather than the lighter side of this range. The first recorded use of old gold as a color name in English was in the early 19th century; the Delta Sigma Pi fraternity, founded in November 7, 1907, official colors are designated royal purple and old gold.
The Pi Kappa Alpha fraternity's colors are old gold. Old gold is one of two colors of Alpha Phi Alpha fraternity. Maroon and old gold are the colors of Texas State University's intercollegiate sports teams. Old Gold and black are the team colors of Purdue University Boilermakers intercollegiate sports teams; the Georgia Tech Yellow Jackets wore white and old gold. The Wake Forest Demon Deacons, UCF Knights, Vanderbilt Commodores wear old gold and black; the New Orleans Saints list their official team colors as old gold and white. Golden yellow is the color halfway between yellow on the RGB color wheel, it is a color, 87.5% yellow and 12.5% red. The first recorded use of golden yellow as a color name in English was in the year 1597. Golden poppy is a tone of gold, the color of the California poppy—the official state flower of California—the Golden State; the first recorded use of golden poppy as a color name in English was in 1927. Gold is the oldest color associated with Arizona State University and dates back to 1896 when the school was named the Tempe Normal School.
Gold signifies the "golden promise" of ASU. The promise includes every student receiving a valuable educational experience. Gold signifies the sunshine Arizona is famous for; the student section, known as The Inferno, wears gold on game days. The official colors of the University of Southern California are Pantone 201C and Pantone 123C; these colors, designated as USC Cardinal and USC Gold, were adopted in 1895 by Rev. George W. White, USC’s third president, are equal in importance in identifying the USC Trojans; this is a shade of gold identified by the University of California, Berkeley in their graphic style guide for use in on-screen representations of the gold color in the university's seal. For print media, the guide recommends to, "se Pantone 7750 metallic or Pantone 123 yellow and 282 blue". Cal Poly Pomona gold is one of the two the official colors of California State Polytechnic University, Pomona; the official university colors are gold. Cal Poly Pomona's Office of Public Affairs created the colors for web development and has technical guidelines and privacy protection.
If web developers are using gold on a university website, they are encouraged to use Cal Poly Pomona gold. It is notable for its prominent use representing Cal Poly Pomona's athletic teams, the Cal Poly Pomona Broncos; the color was approved by the University of California, Los Angeles Chancellor in October 2013. This is a shade of gold identified by the university for use in their printed publications. MU Gold is used by the University of Missouri as the official school color along with black. Mizzou Identity Standards designated the color for web development as well as logos and images that developers are asked to follow in the University's Guidelines for using official Mizzou logos; the color pale gold is displayed
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses and to serve as a navigational aid for maritime pilots at sea or on inland waterways. Lighthouses mark dangerous coastlines, hazardous shoals, reefs and safe entries to harbors. Once used, the number of operational lighthouses has declined due to the expense of maintenance and use of electronic navigational systems. Before the development of defined ports, mariners were guided by fires built on hilltops. Since raising the fire would improve the visibility, placing the fire on a platform became a practice that led to the development of the lighthouse. In antiquity, the lighthouse functioned more as an entrance marker to ports than as a warning signal for reefs and promontories, unlike many modern lighthouses; the most famous lighthouse structure from antiquity was the Pharos of Alexandria, which collapsed following a series of earthquakes between 956 and 1323. The intact Tower of Hercules at A Coruña, Spain gives insight into ancient lighthouse construction.
Coins from Alexandria and Laodicea in Syria exist. The modern era of lighthouses began at the turn of the 18th century, as lighthouse construction boomed in lockstep with burgeoning levels of transatlantic commerce. Advances in structural engineering and new and efficient lighting equipment allowed for the creation of larger and more powerful lighthouses, including ones exposed to the sea; the function of lighthouses shifted toward the provision of a visible warning against shipping hazards, such as rocks or reefs. The Eddystone Rocks were a major shipwreck hazard for mariners sailing through the English Channel; the first lighthouse built there was an octagonal wooden structure, anchored by 12 iron stanchions secured in the rock, was built by Henry Winstanley from 1696 to 1698. His lighthouse was the first tower in the world to have been exposed to the open sea; the civil engineer, John Smeaton, rebuilt the lighthouse from 1756–59. He modelled the shape of his lighthouse on that of an oak tree.
He rediscovered and used "hydraulic lime," a form of concrete that will set under water used by the Romans, developed a technique of securing the granite blocks together using dovetail joints and marble dowels. The dovetailing feature served to improve the structural stability, although Smeaton had to taper the thickness of the tower towards the top, for which he curved the tower inwards on a gentle gradient; this profile had the added advantage of allowing some of the energy of the waves to dissipate on impact with the walls. His lighthouse influenced all subsequent engineers. One such influence was Robert Stevenson, himself a seminal figure in the development of lighthouse design and construction, his greatest achievement was the construction of the Bell Rock Lighthouse in 1810, one of the most impressive feats of engineering of the age. This structure was based upon Smeaton's design, but with several improved features, such as the incorporation of rotating lights, alternating between red and white.
Stevenson worked for the Northern Lighthouse Board for nearly fifty years during which time he designed and oversaw the construction and improvement of numerous lighthouses. He innovated in the choice of light sources, reflector design, the use of Fresnel lenses, in rotation and shuttering systems providing lighthouses with individual signatures allowing them to be identified by seafarers, he invented the movable jib and the balance crane as a necessary part for lighthouse construction. Alexander Mitchell designed the first screw-pile lighthouse – his lighthouse was built on piles that were screwed into the sandy or muddy seabed. Construction of his design began in 1838 at the mouth of the Thames and was known as the Maplin Sands lighthouse, first lit in 1841. Although its construction began the Wyre Light in Fleetwood, was the first to be lit; the source of illumination had been wood pyres or burning coal. The Argand lamp, invented in 1782 by the Swiss scientist, Aimé Argand, revolutionized lighthouse illumination with its steady smokeless flame.
Early models used ground glass, sometimes tinted around the wick. Models used a mantle of thorium dioxide suspended over the flame, creating a bright, steady light; the Argand lamp used whale oil, olive oil or other vegetable oil as fuel, supplied by a gravity feed from a reservoir mounted above the burner. The lamp was first produced by Matthew Boulton, in partnership with Argand, in 1784 and became the standard for lighthouses for over a century. South Foreland Lighthouse was the first tower to use an electric light in 1875; the lighthouse's carbon arc lamps were powered by a steam-driven magneto. John Richardson Wigham was the first to develop a system for gas illumination of lighthouses, his improved gas'crocus' burner at the Baily Lighthouse near Dublin was 13 times more powerful than the most brilliant light known. The vaporized oil burner was invented in 1901 by Arthur Kitson, improved by David Hood at Trinity House; the fuel was vaporized at high pressure and burned to heat the mantle, giving an output of over six times the luminosity of traditional oil lights.
The use of gas as illuminant became available with the invention of the Dalén light by Swedish engineer, Gustaf Dalén. He used Agamassan, a substrate, to absorb the gas allowing safe storage and hence
A navy or maritime force is the branch of a nation's armed forces principally designated for naval and amphibious warfare. It includes anything conducted by surface ships, amphibious ships and seaborne aviation, as well as ancillary support, communications and other fields; the strategic offensive role of a navy is projection of force into areas beyond a country's shores. The strategic defensive purpose of a navy is to frustrate seaborne projection-of-force by enemies; the strategic task of the navy may incorporate nuclear deterrence by use of submarine-launched ballistic missiles. Naval operations can be broadly divided between riverine and littoral applications, open-ocean applications, something in between, although these distinctions are more about strategic scope than tactical or operational division. In most nations, the term "naval", as opposed to "navy", is interpreted as encompassing all maritime military forces, e.g. navy, naval infantry/marine corps, coast guard forces. First attested in English in the early 14th century, the word "navy" came via Old French navie, "fleet of ships", from the Latin navigium, "a vessel, a ship, boat", from navis, "ship".
The word "naval" came from Latin navalis, "pertaining to ship". The earliest attested form of the word is in the Mycenaean Greek compound word, na-u-do-mo, "shipbuilders", written in Linear B syllabic script; the word denoted fleets of both commercial and military nature. In modern usage "navy" used alone always denotes a military fleet, although the term "merchant navy" for a commercial fleet still incorporates the non-military word sense; this overlap in word senses between commercial and military fleets grew out of the inherently dual-use nature of fleets. Although nationality of commercial vessels has little importance in peacetime trade other than for tax avoidance, it can have greater meaning during wartime, when supply chains become matters of patriotic attack and defense, when in some cases private vessels are temporarily converted to military vessels; the latter was important, common, before 20th-century military technology existed, when adding artillery and naval infantry to any sailing vessel could render it as martial as any military-owned vessel.
Such privateering has been rendered obsolete in blue-water strategy since modern missile and aircraft systems grew to leapfrog over artillery and infantry in many respects. Naval warfare developed. Prior to the introduction of the cannon and ships with sufficient capacity to carry the large guns, navy warfare involved ramming and boarding actions. In the time of ancient Greece and the Roman Empire, naval warfare centered on long, narrow vessels powered by banks of oarsmen designed to ram and sink enemy vessels or come alongside the enemy vessel so its occupants could be attacked hand-to-hand. Naval warfare continued in this vein through the Middle Ages until the cannon became commonplace and capable of being reloaded enough to be reused in the same battle; the Chola Dynasty of medieval India was known as one of the greatest naval powers of its time from 300 BC to 1279 AD. The Chola Navy, Chola kadarpadai comprised the naval forces of the Chola Empire along with several other Naval-arms of the country.
The Chola navy played a vital role in the expansion of the Chola Tamil kingdom, including the conquest of the Sri Lanka islands, Sri Vijaya, the spread of Hinduism, Tamil architecture and Tamil culture to Southeast Asia and in curbing the piracy in Southeast Asia in 900 CE. In ancient China, large naval battles were known since the Qin dynasty, employing the war junk during the Han dynasty. However, China's first official standing navy was not established until the Southern Song dynasty in the 12th century, a time when gunpowder was a revolutionary new application to warfare. Nusantaran thalassocracies made extensive use of naval power and technologies; this enabled the seafaring Malay people to attack as far as the coast of Tanganyika and Mozambique with 1000 boats and attempted to take the citadel of Qanbaloh, about 7,000 km to their West, in 945-946 AD. In 1350 AD Majapahit launched its largest military expedition, the invasion of Pasai, with 400 large jong and innumerable smaller vessels.
The second largest military expedition, invasion of Singapura in 1398, Majapahit deployed 300 jong with no less than 200,000 men. The mass and deck space required to carry a large number of cannon made oar-based propulsion impossible, ships came to rely on sails. Warships were designed to carry increasing numbers of cannon and naval tactics evolved to bring a ship's firepower to bear in a broadside, with ships-of-the-line arranged in a line of battle; the development of large capacity, sail-powered ships carrying cannon led to a rapid expansion of European navies the Spanish and Portuguese navies which dominated in the 16th and early 17th centuries, helped propel the age of exploration and colonialism. The repulsion of the Spanish Armada by the English fleet revolutionized naval warfare by the succe
Cyan is a greenish-blue color. It is evoked by light with a predominant wavelength of between 490–520 nm, between the wavelengths of green and blue. In the subtractive color system, or CMYK, which can be overlaid to produce all colors in paint and color printing, cyan is one of the primary colors, along with magenta and black. In the additive color system, or RGB color model, used to create all the colors on a computer or television display, cyan is made by mixing equal amounts of green and blue light. Cyan is the complement of red. Mixing red light and cyan light at the right intensity will make white light; the web color cyan is synonymous with aqua. Other colors in the cyan color range are teal, electric blue and others described as blue-green, its name is derived from the Ancient Greek κύανος, transliterated kyanos, meaning "dark blue, dark blue enamel, Lapis lazuli". It was known as "cyan blue" or cyan-blue, its first recorded use as a color name in English was in 1879. Further origins of the color name can be traced back to a dye produced from the cornflower.
In most languages,'cyan' is not a basic color term and it phenomenologically appears as a greenish vibrant hue of blue to most English speakers. Reasons for why cyan is not linguistically acknowledged as a basic color term can be found in the frequent lack of distinction between blue and green in many languages; the web color cyan shown at right is a secondary color in the RGB color model, which uses combinations of red and blue light to create all the colors on computer and television displays. In X11 colors, this color is called both aqua. In the HTML color list, this same color is called aqua; the web colors are more vivid than the cyan used in the CMYK color system, the web colors cannot be reproduced on a printed page. To reproduce the web color cyan in inks, it is necessary to add some white ink to the printer's cyan below, so when it is reproduced in printing, it is not a primary subtractive color, it is called aqua because it is a color associated with water, such as the appearance of the water at a tropical beach.
Cyan is one of the common inks used in four-color printing, along with magenta and black. While both the additive secondary and the subtractive primary are called cyan, they can be different from one another. Cyan printing ink can be more saturated or less saturated than the RGB secondary cyan, depending on what RGB color space and ink are considered. Process cyan is not an RGB color, there is no fixed conversion from CMYK primaries to RGB. Different formulations are used for printer's ink, so there can be variations in the printed color, pure cyan ink; this is because real-world subtractive color mixing does not produce the same result when mixing identical colors, since the specific frequencies filtered out to produce that color affect how it interacts with other colors. Phthalocyanine blue is one such used pigment. A typical formulation of process cyan is shown in the color box at right. Pure water is nearly colorless. However, it does absorb more red light than blue, giving large volumes of water a bluish tint.
Cyanide derives its name from a blue pigment containing the cyanide ion. Cyanobacteria are an important link in the food chain; the planet Uranus is colored cyan because of the abundance of methane in its atmosphere. Methane absorbs red light and reflects the blue-green light which allows observers to see it as cyan. Natural gas, used by many for home cooking on gas stoves, has a cyan colored flame when burned with a mixture of air. Cyanotype, or blueprint, a monochrome photographic printing process that predates the use of the word cyan as a color, yields a deep cyan-blue colored print based on the Prussian blue pigment. Cinecolor, a bi-pack color process, the photographer would load a standard camera with two films, one orthochromatic, dyed red, a panchromatic strip behind it. Color light would expose the cyan record on the ortho stock, which acted as a filter, exposing only red light to the panchromatic film stock. Cyanosis is an abnormal blueness of the skin a sign of poor oxygen intake. I.e. the patient is "cyanotic".
Cyan is associated with the throat chakra in vedic medicine. In the 19th century, surgeons wore white gowns, but in the 20th century surgeons began to wear cyan or green surgical gowns, for several reasons. First, in the brightly lit operating room, cyan reflected less light than white and caused less strain on the eyes of the medical team. Second, cyan is the complementary color of red, so red blood on a cyan gown looks black or gray rather than red, is not as vivid. Shifting your sight to cyan after staring at red for long periods of time does not cause cyan after-images, as shifting from red to white will do. Lastly, since cyan is considered a restful and soothing color, it causes less anxiety in patients. Blue–green distinction in language Shades of cyan List of colors