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the free encyclopedia that anyone can edit. 6,822,455 articles in English. From today's featured article. Leucippus was a Greek philosopher of the 5th century BCE. He is credited with founding atomism, with his student Democritus. Leucippus divided the world into two entities: atoms, indivisible particles that make up all things, and the void ...
QWERTY ( / ˈkwɜːrti / KWUR-tee) is a keyboard layout for Latin-script alphabets. The name comes from the order of the first six keys on the top letter row of the keyboard: Q W E R T Y. The QWERTY design is based on a layout included in the Sholes and Glidden typewriter sold via E. Remington and Sons from 1874.
Leonardo di ser Piero da Vinci [b] (15 April 1452 – 2 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, draughtsman, engineer, scientist, theorist, sculptor, and architect. [3] While his fame initially rested on his achievements as a painter, he has also become known for his notebooks, in which he made ...
- Visibility
- Number of Colours in A Spectrum Or A Rainbow
- Explanation
- Variations
- Scientific History
- Experiments
- Culture and Mythology
- See Also
- Further Reading
- External Links
Rainbows can be observed whenever there are water drops in the air and sunlight shining from behind the observer at a low altitude angle. Because of this, rainbows are usually seen in the western sky during the morning and in the eastern sky during the early evening. The most spectacular rainbow displays happen when half the sky is still dark with ...
For colours seen by the human eye, the most commonly cited and remembered sequence is Isaac Newton's sevenfold red, orange, yellow, green, blue, indigo and violet,[a] remembered by the mnemonic Richard Of York Gave Battle In Vain, or as the name of a fictional person (Roy G. Biv). The initialism is sometimes referred to in reverse order, as VIBGYOR...
When sunlight encounters a raindrop, part of the light is reflected and the rest enters the raindrop. The light is refracted at the surface of the raindrop. When this light hits the back of the raindrop, some of it is reflected off the back. When the internally reflected light reaches the surface again, once more some is internally reflected and so...
Double rainbows
A secondary rainbow, at a greater angle than the primary rainbow, is often visible. The term double rainbowis used when both the primary and secondary rainbows are visible. In theory, all rainbows are double rainbows, but since the secondary bow is always fainter than the primary, it may be too weak to spot in practice. Secondary rainbows are caused by a double reflection of sunlight inside the water droplets. Technically the secondary bow is centred on the sun itself, but since its angular s...
Twinned rainbow
Unlike a double rainbow that consists of two separate and concentric rainbow arcs, the very rare twinned rainbow appears as two rainbow arcs that split from a single base. The colours in the second bow, rather than reversing as in a secondary rainbow, appear in the same order as the primary rainbow. A "normal" secondary rainbow may be present as well. Twinned rainbows can look similar to, but should not be confused with supernumerary bands. The two phenomena may be told apart by their differe...
Full-circle rainbow
In theory, every rainbow is a circle, but from the ground, usually only its upper half can be seen. Since the rainbow's centre is diametrically opposed to the Sun's position in the sky, more of the circle comes into view as the sun approaches the horizon, meaning that the largest section of the circle normally seen is about 50% during sunset or sunrise. Viewing the rainbow's lower half requires the presence of water droplets below the observer's horizon, as well as sunlight that is able to re...
The classical Greek scholar Aristotle (384–322 BC) was first to devote serious attention to the rainbow.According to Raymond L. Lee and Alistair B. Fraser, "Despite its many flaws and its appeal to Pythagorean numerology, Aristotle's qualitative explanation showed an inventiveness and relative consistency that was unmatched for centuries. After Ari...
Experiments on the rainbow phenomenon using artificial raindrops, i.e. water-filled spherical flasks, go back at least to Theodoric of Freiberg in the 14th century. Later, also Descartes studied the phenomenon using a Florence flask. A flask experiment known as Florence's rainbow is still often used today as an imposing and intuitively accessible d...
Rainbows occur frequently in mythology, and have been used in the arts. The first literary occurrence of a rainbow is in the Book of Genesis chapter 9, as part of the flood story of Noah, where it is a sign of God's covenant to never destroy all life on Earth with a global flood again. In Norse mythology, the rainbow bridge Bifröst connects the wor...
Boyer, Carl B. (1987). The Rainbow, From Myth to Mathematics. Princeton University Press. ISBN 978-0-691-08457-2.De Rico, Ul (1978). The Rainbow Goblins. Thames & Hudson. ISBN 978-0-500-27759-1.Graham, Lanier F., ed. (1976). The Rainbow Book. Berkeley, California: Shambhala Publications and The Fine Arts Museums of San Francisco. (Large format handbook for the Summer 1976 exhibition The R...Greenler, Robert (1980). Rainbows, Halos, and Glories. Cambridge University Press. ISBN 978-0-19-521833-6.The Mathematics of Rainbows, article from the American mathematical societyAtmospheric Optics website by Les Cowley– Description of multiple types of bows, including: "bows that cross, red bows, twinned bows, coloured fringes, dark bands, spokes", etc.Macau [e] or Macao [f] is a special administrative region of the People's Republic of China. With a population of about 680,000 [11] and an area of 32.9 km 2 (12.7 sq mi), it is the most densely populated region in the world. Formerly a Portuguese colony, the territory of Portuguese Macau was first leased to Portugal by the Ming dynasty as a ...
Bill Gates. William Henry Gates III (born October 28, 1955) is an American businessman, investor, philanthropist, and writer best known for co-founding the software giant Microsoft, along with his childhood friend Paul Allen. During his career at Microsoft, Gates held the positions of chairman, chief executive officer (CEO), president, and ...
SpongeBob SquarePants is an American animated television series created by marine science educator and animator Stephen Hillenburg that aired on Nickelodeon as a sneak peek after the 1999 Kids' Choice Awards on May 1, 1999, and officially premiered on July 17, 1999. It chronicles the adventures of the title character and his aquatic friends in ...
