why the rainbow is colorful?
465572
because the bands of color that appears when the Sun's rays are refracted and reflected by drops of mist or rain. The colors of the rainbow are conventionally said to be red, orange, yellow, green, blue, indigo, and violet.\nIn shorter words the drops of water work like a prism that when are touched by the sun'srays thansform light into many colors that then form many bands called rainbow.
483599
the other answers are somewhat correct but unnecessarily long....\n\n1. the rainbow is actually a circle that is partially visible as an arch due     \n    horizon limitations.\n\n2.  it is a circle because the light source ( the sun ) is a circle.
180235
I won't give you a cut-paste answer, but this is my favourite rainbow explanation site:\nhttp://www.gryndlscot.com/rainbow.html
507580
A rainbow is an optical and meteorological phenomenon that causes a nearly continuous spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth's atmosphere. It takes the form of a multicoloured arc, with red on the outside and violet on the inside. Even though a rainbow spans a continuous spectrum of colours, traditionally the full sequence of colours is most commonly cited as red, orange, yellow, green, blue, indigo, and violet. It is commonly thought that indigo was included due to the different religious connotations of the numbers six and seven at the time of Isaac Newton's work on light, despite its lack of scientific significance and the poor ability of humans to distinguish colours in the blue portion of the visual spectrum.\n\n\nThe rainbow effect can be observed whenever there are water drops in the air and sunlight shining from behind the observer at a low altitude or angle. The most spectacular rainbow displays when half of the sky is still dark with draining clouds and the observer is at a spot with clear sky overhead. The rainbow effect is also commonly seen near waterfalls or fountains. Rainbow fringes can sometimes be seen at the edges of backlit clouds and as vertical bands in distant rain or virga. The effect can also be artificially created by dispersing water droplets into the air during a sunny day.\n\nIn a very few cases, a moonbow, or night-time rainbow, can be seen on strongly moonlit nights. As human visual perception for colour in low light is poor, moonbows are perceived to be white.\n\nThe rainbow's appearance is caused by dispersion of sunlight as it is refracted by (approximately spherical) raindrops. The light is first refracted as it enters the surface of the raindrop, reflected off the back of the drop, and again refracted as it leaves the drop. The overall effect is that the incoming light is reflected back over a wide range of angles, with the most intense light at an angle of about 40°–42°, regardless of the size of the drop. Since the water of the raindrops is dispersive, the amount that the sunlight is bent depends upon the wavelength, and hence colour, of the light's constituent parts. Blue light is refracted at a greater angle than red light, but because the area of the back of the droplet has a focal point inside the droplet, the spectrum crosses itself, and therefore the red light appears higher in the sky, and forms the outer colour of the rainbow. Contrary to popular belief, the light at the back of the raindrop does not undergo total internal reflection; however, light that emerges from the back of the raindrop does not create a rainbow between the observer and the Sun. The spectra emitted from the back of the raindrop do not have a maximum of intensity, as the other visible rainbows do, and thus the colours blend together and do not form a rainbow.\n\nA rainbow does not actually exist at a location in the sky, but rather is an optical phenomenon whose apparent position depends on the observer's location. All raindrops refract and reflect the sunlight in the same way, but only the light from some raindrops reaches the observer's eye. These raindrops are perceived to constitute the rainbow by that observer. The position of a rainbow in the sky is always in the opposite direction of the Sun with respect to the observer, and the interior is always slightly brighter than the exterior. The bow is centred on the shadow of the observer's head, or more exactly at the antisolar point (which is below the horizon during the daytime), appearing at an angle of approximately 40°–42° to the line between the observer's head and its shadow. As a result, if the Sun is higher than 42°, then the rainbow is below the horizon and cannot be seen unless the observer is at the top of a mountain or a similar vantage point. Similarly, it is difficult to photograph the complete arc of a rainbow, which would require an angle of vie
110830
Umm.. No. Rainbows are a result of atmospheric moisture and light, not a short Irish man who tricks kids into buying overpriced cereal.
386869
The rainbow has a place in legend due to its beauty and the difficulty in explaining the phenomenon before the work of Descartes in the 17th century (although, as mentioned above, Theodoric of Freiburg had given a satisfactory explanation in the 13th century.)\n\nIn Greek mythology, the rainbow considered to be a path made by a messenger (Iris) between Earth and Heaven. In Chinese mythology, the rainbow was a slit in the sky sealed by Goddess Nüwa using stones of five 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 Bifröst Bridge connects the realms of Ásgard and Midgard, homes of the gods and humans, respectively. The Irish leprechaun's secret hiding place for his crock of gold is usually said to be at the end of the rainbow (which, of course, one can never reach). 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 entire Earth\n\n\nVIBGYOR...
203928
Rainbows are made from light reflecting off the small droplets of water in the air, usually after it just rained so it doesn't really travel any differently...
1173045
You know how you see a rainbow when its really humid, or when it rains and there is sun? Thats what you saw, you saw a rainbow, but not a half rainbow, but rather a whole rainbow around the sun. A ring rainbow, this is due because of the high humidity that is in the air, its the same as a rainbow, just around the sun.
384059
Double rainbows are a rarity.\n\n\n\n\n \nThe Double Rainbow\n\n \n\n\nEvery once in a while, if you get lucky, you may see a second rainbow on the outside of the first, brighter rainbow. This is the "secondary rainbow" which occurs when raindrops high in the atmosphere refract and reflect light back to the viewer. \n\nThese raindrops are higher than those which cause the "primary rainbow" and are special because they internally reflect the incoming sunlight twice rather than just once. \n\n\n\nNotice that the sunlight hits the bottom of the raindrop to make the secondary rainbow. There is still sunlight hitting the other parts of the raindrop, however, some of the light is simply transmitted through the raindrop without reflecting, and some light is reflected and refracted, but not into our eyes: that light is for someone else's rainbow. \n\nNotice also in the image at the top of the page that the sequence of colors in the secondary rainbow is switched compared to the primary bow. Why is this? \n\n\n\n\n\n--------------------------------------------------------------------------------
781942
Why not teach on the first rainbow; in the story of Noah? The rainbow represents G-d's promise to never destroy the world again with a flood. Rainbows represent mercy.
524651
Cloud Rainbow, same thing, the light passes thru the moisture, you get a rainbow. I love them no matter how scientific I can get abut it.
1043751
Sometimes we see two rainbows at once, what causes this? We have followed the path of a ray of sunlight as it enters and is reflected inside the raindrop. But not all of the energy of the ray escapes the raindrop after it is reflected once. A part of the ray is reflected again and travels along inside the drop to emerge from the drop. The rainbow we normally see is called the primary rainbow and is produced by one internal reflection; the secondary rainbow arises from two internal reflections and the rays exit the drop at an angle of 50 degrees° rather than the 42°degrees for the red primary bow. Blue light emerges at an even larger angle of 53 degrees°. his effect produces a secondary rainbow that has its colors reversed compared to the primary, as illustrated in the drawing, adapted from the Science Universe Series Sight, Light, and Color. \nIt is possible for light to be reflected more than twice within a raindrop, and one can calculate where the higher order rainbows might be seen; but these are never seen in normal circumstances.
715473
A rainbow is formed when sunlight passes through water droplets.  The light is bent allowing the entire color spectrum to be visible.  The color spectrum is always present, but not always visible to the naked eye.  A prism also produces the same effect as it also bends the light allowing the color spectrum to be visible  This is also why the sky is blue.  The light is bent as it passes through the atmosphere and allowing the color blue to be visible to the naked eye.  This process is know as refraction.
335678
It's an acronym that is used to remember the colors in the rainbow.\nRed\nOrange\nYellow\nGreen \nBlue\nIndigo\nViolet
1103987
Rainbows are caused by dispersion of sunlight as it is refracted by (approximately spherical) raindrops. The light is first refracted as it enters the surface of the raindrop, reflects off the back of the drop, and is again refracted as it leaves the drop. The overall effect is that the incoming light is reflected back over a wide range of angles, with the most intense light at an angle of about 40°–42°, regardless of the size of the drop. Since the water of the raindrops is dispersive, the amount that the sunlight is bent depends upon the wavelength (color) of the light's constituent parts. Blue light is refracted at a greater angle than red light, but because the area of the back of the droplet has a focal point inside the droplet, the spectra crosses itself, and thus the red light appears higher in the sky, and forms the outer color of the rainbow.\n\nA rainbow is an optical phenomenon whose apparent position depends on the observer's location. All raindrops refract and reflect the sunlight in the same way, but only the light from some raindrops reaches the observer's eye. These raindrops are perceived to constitute the rainbow by that observer. Its position is always in the opposite direction of the sun with respect to the observer, and the interior is actually a magnified image of the sun, which can be seen to be slightly brighter than the exterior. The bow is centred on the shadow of the observer's head, or more exactly at the antisolar point (which is below the horizon during the daytime), appearing at an angle of approximately 40°–42° to the line between the observer's head and its shadow (this means that if the sun is higher than 42° the rainbow is below the horizon and cannot be seen unless the observer is at the top of a mountain or a similar vantage point).\n\nSometimes, a second, dimmer rainbow is seen outside the primary bow, caused by a double reflection of the sunlight inside the raindrops, and appears at an angle of 50°–53°. Because of the extra reflection, the colours of the bow are inverted compared to the primary bow, with blue on the outside and red on the inside. (The full sequence of colors is red, orange, yellow, green, cyan, blue and violet.)\n\nA triple rainbow is even more rarely seen. A few observers have reported seeing quadruple rainbows in which a dim outermost arc had a rippling and pulsating appearance.
64520
Its the refraction of light, through water droplets. Rainbows can only be seen when the sun is at your back or behind you.
416298
A full moon can form a rainbow - usually called a "moonbow". It looks kind of grey though.