The rainbow is an optical and meteorological phenomenon that causes the about continuous spectrum of light to appear in the sky when the sun shines onto falling rain. These are the multicoloured arc with red on the outside and violet on the inside. A to the full sequence of colours is most normally cited when red, orange, yellow, green, blue, indigo, and violet, though it is significant to note that this is an inconsistent names; everthing primary and secondary colours are present inside a bit of form, but only of these tertiary period. These are normally thought that indigo was involved due to the different religious connotations of the numbers six and seven at the period of Isaac Newton's work in weak, despite its want of scientific significance & a unfortunate ability of homo to distinguish colorize the blue part of the visual spectrum.

A rainbow consequence may be found anytime there are water drops in the air & sunlight shining from behind the observer at a great altitude or angle. A virtually all outstanding rainbow displays whilst half of the sky is still dark sustaining draining clouds and the observer is at a spot using clear sky overhead. An additional most common place to view a rainbow burden is touching waterfalls. Rainbow fringes may periodically become seen at a edges of backlit clouds & when vertical elastic within distant rain or even virga. the symptom can likewise exist as by artificial means created by dispersing a water system droplets into a air in the period of a sunny day.

Inside the super couple subjects, the moonbow, or night-time rainbow, may be seen in strongly moony nights. When individual visual perception for colour in moo weak is unfortunate, moonbows come perceived to exist as white.

Physics of rainbows

A rainbow's appearance is from either dispersion of sunlight when these are refracted by (approximately globular) raindrops. A weak is 1st refracted when it enters a surface of the raindrop, reflects off a back of the drop, & is over again refracted when it leaves the drop. the overall symptom is that a incoming weak is reflected back across a wide range of angles, with a virtually all unbearable weak at an angle of astir 40°–42°, disregardless of the size of the drop. Since a water supply of a raindrops is disseminating, a total that a sun is bent depends upon the wavelength (colour) of the light's constitutional area. Blue weak is refracted at a greater angle than red light, however because a locality of a back of the droplet has a focal point in the droplet, the spectra crosses itself, & so a red weak appears higher in a sky, and forms the outer colour of the rainbow. Contrary to popular belief, a weak at a back of the raindrop doesn't undergo total internal reflection; however, weak that emerges from either a back of a raindrop doesn't produce a rainbow between the observer & the sun. This is because a emitted spectra there don't have a maximal of intensity, when a more seeable rainbows wash. So a colours blend together & don't form any rainbow. The rainbow doesn't actually survive at the location in the sky, however is an optical phenomenon whose apparent position depends on the observer's location. Tons raindrops refract & reflect a sunshine in a equivalent way, but only a weak from either a select few raindrops reaches the observer's eye. These raindrops come perceived to be a rainbow by that observer. Its position is universally in a paired counsel of the sun by using respect to the observer, & the interior is actually a enlarged image of the sun, which may exist as seen to be slightly brilliantly than the exterior. A bow is centred on the shadow of the observer's head, or even thomas more exactly at a antisolar point (which is below a horizon in a period of the day), appearing at an angle of close to 40°–42° to a line between the observer's head & its shadow (this means that in case the sun is higher than 42° the rainbow is in a image below a horizon & just can not exist as seen unless a observer is at the top of a mountain or even a similar vantage point). Likewise these are hard to photograph the complete arc of a rainbow, which would necessitate an angle of view of 84°. For the 35 mm camera, a lens with a focal length of 19 mm or less would be required, whilst most photographers are only likely to have a 28 mm wide-angle lens. From either an aeroplane one has a chance to look at a altogether circle of the rainbow, by owning the plane's shadow in the centre. Such the complete 'raincircle' (potentially even double) can besides exist as seen from either behind a falls because the waterdrops come nearer, in the falls. Across such the short few feet away the 40° angle corresponds to a shorter across.

Periodically, another, dimmed rainbow is seen outside a primary bow, from either a double reflection of the sun in the raindrops, & appears at an angle of 50°–53°. Because of a additional reflection, a colours of the bow come inverted in comparison the primary bow, by having blue on the outside & red on the in. Alexander's band is an area of unlit sky lying between the primary and secondary bows. The triple rainbow is possibly extra seldom seen. Two or three observers keep around reported seeing quadruple rainbows where the dimmed outmost arc experienced the ripple & beating appearance. These rainbows would pop up on a equivalent side of the sky when the sun, making the babies harder to spot.

Now & then, an additional beautiful & striking rainbow phenomenon can be found, consisting of many swoon rainbows on a inner side of the primary rainbow, and super seldom as well outside the secondary rainbow. It is slightly detached & develop pastel colour elastic that don't healthy a common pattern. It is referred to as [http://www.sundog.clara.co.uk/rainbows/supers.htm supernumerary rainbows], & their super being was historically the foremost indication of the wave nature and severity of weak.

More rainbow variants come ones produced while a sun reflects dispatch a water prior to reaching the raindrops. This garden truck the [http://www.sundog.clara.co.uk/rainbows/reflect.htm reflection rainbow] which shares the equivalent end point while a normal 1 however encompasses a far greater arc when a lot of these are seeable. Reflection rainbows may survive for each a primary & secondary. a reflected rainbow is produced once weak that has been reflected in the raindrops reflects polish off a water prior to reaching the observer. These are non the reflexion of the primary, existence displaced from either it to the degree contingent on the sun's altitude. Below each types may be seen. A reflection rainbow is faintly seeable curving between a primary & secondary, & a reflected rainbow may be seen in the a stream.

A Persian stargazer Qutb al-Din al-Shirazi is thought to have number one given the fairly precise explanation for the rainbow phenomenon. Theodoric of Freiberg is also known to use given an precise theoretical explanatiin of a rainbow inside 1307; he postulated that whenever sun lessens on human drops of wet, a rays undergo 2 refractions (upon ingress & egress) & 1 reflection (at a back side of the drop) prior to transmission into the eye of the observer" (quoted from David C, Lindberg, “Roger Bacon’s Theory of the Rainbow: Progress or Regress?”, Isis, Vol. 57, no. 2, p. 236.).

Descartes, in 1637, further advanced this explanation. Knowing that the size of raindrops didn't appear to affect the observed rainbow, he experimented with passing rays of light through a large glass sphere filled with water. By measuring the angles that the rays emerged, he concluded that the primary bow was caused by a single internal reflection inside the raindrop and that a secondary bow could be caused by two internal reflections. He was able to back this up with a derivation of the law of refraction (subsequently, but independently of Snell) and correctly calculated the angles for both bows. However, he was unable to explain the colours.

Isaac Newton was the first to demonstrate that white light was composed of the light of all the colours of the rainbow, which a glass prism could split into the full spectrum of colours. He also showed that red light gets refracted less than blue light, which led to the first scientific explanation of the major rainbow features.

Advances in computational methods and optical theory continue to lead to a fuller understanding of rainbows. The article by Nussenzveig listed in the references provides a modern overview.

Rainbows in religion and mythology

The rainbow has a place in legend due to its beauty and the difficulty in explaining the phenomenon before Galileo's treatise on the properties of light. In Greek mythology, it is a path made by a messenger (Iris) between Earth and Heaven. In the Hebrew Bible, the rainbow is a symbol of the covenant between God and man, and God's promise to Noah that He would never again flood the Earth. The Irish leprechaun's secret hiding place for his crock of gold is usually said to be at the end of the rainbow. In Chinese mythology, the rainbow was a slit in the sky sealed by Goddess Nüwa using stones of seven different colours. In Hindu mythology, the rainbow is called Indradhanush—meaning the bow of Indra, the God of lightning and thunder. In Norse Mythology, a rainbow called the Bifrost Bridge connects the realms of Ã?sgard and Midgard, homes of the gods and humans, respectively.

Rainbows in literature
The rainbow has also been used in more contemporary settings, such as the song "On top a Rainbow" in the musical film The Wizard of Oz, and in selling Lucky Charms by alluding heavily to leprechaun mythology. One of the poems of William Wordsworth goes...

However, the Newtonian deconstruction of the rainbow is said to have provoked John Keats to lament....

In contrast to this is Richard Dawkins; talking about his book Unweaving the Rainbow: Science, Delusion and the Appetite for Wonder .....

"Our title is from either Keats, world health organization believed that Newton got destroyed all the poetry of the rainbow by reducing it to the prismatic colours. Keats may hardly use been extra wrong, & our aim is to guide completely world health organization come tempted by a similar look at, towards the paired guide. Science is, or even ought to become, a inspiration for neat poetry."

Science merely explains the phenomena though; it doesn't create it.

Remembering the sequence of colours
A traditional way of recalling each of the seven colours of the rainbow in sequence is by using the mnemonic "Richard Of York Gave Battle Inorth Vown", where the first letter of each word corresponds to the first letter of each colour. The mnemonic alludes to the defeat of Richard III by Henry Tudor at the Battle of Bosworth Field.

Another, less obvious, though more common way is the use of the meaningless name Roy G. Biv. This method is purely phonetic. A drawback to both of these methods is that they include the colour of indigo between blue and violet, though most modern rainbow definitions do not include that as a distinct colour.

Since rainbows are composed of a nearly continuous spectrum, different people, most notably across different cultures, identify different numbers of colours in rainbows.