What is a double rainbow?
147785
It is a second rainbow caused by the way light reflects inside of raindrops.  They will appear between 50 and 53 degrees above the horizon and the colors are inverted.  There is also a band of darker sky between the two, this is called an Alexander's band.
172613
We can see two simultaneously rainbows sometimes. The first one is produced by one internal reflection inside the raindrop, and the second one is produced by two internal reflections.\nTheorically, light can reflect more times inside the raindrop, but I think nobody has seen a third rainbow.
318480
Yes it is rainbow. Here is the Russian spelling of it: "радуга"
1107176
a rainbow? stuffed if i know....lol
888300
what you actually saw was the two rainbows formed...\nyes there are two... as what you saw, the outside is fainter than the inside... and also, if there were no earth, the rainbow we see will be like a circle....
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.
655891
It doesn't matter if the rainbow appears around the sun or on the ground after a rainshower. The two rainbows are called primary and secondary bows. There are two because the sunlight is relected off the inside of a water droplet twice instead of once; once would result in only one rainbow. This all depends on the angle in which the sunlight enters the water droplet.\nThe secondary bow is fainter and  the colors are reversed.
1036257
Double Rainbows are stunning!\n\nThe phenomenon is basically a main primary rainbow with a secondary rainbow that forms outside the primary bow. The secondary bow is weaker in brightness than the primary (it forms from a second reflection in raindrops, rather than from just one as with the primary bow), and its colors are reversed in order. In the primary bow, blue is on the inner edge with red on the outer. In the secondary bow, the red is on the inner edge and blue the outer. In between the two bows you will see a much darker region known as Alexander's dark band. The center of the rainbow is usually much brighter than the rest of the sky due to sunlight reflecting directly back from the droplets to the viewer...\n\n\nThere's a lot on this topic available from a Google search :)
129313
The curvature of the rainbow is a consequence of having only those raindrops that are at the vertices of 42 degree angles between you and the sun. The collection of all these raindrops is of course an arc. \n\nThe light enters the raindrop from behind you, and bounces off its back surface. The colors separate, because each color has a different speed in the water, and therefore refract a different amount.
786396
hi, try this link .. its a nice one ..\n\nhttp://eo.ucar.edu/rainbows/
17125
Theres -3- different meanings. \nThe first is a political party in Greece. \n\nThe second is a group sex event, widely associated with oral activities. \n\nThird. It is the title of a book about kids and group sex.\n\nAlternatively alot of people may be inclided to think this as a gay...event. While the rainbow has widely been a 'gay identifier' this is not the case. The name was generated from girls that would wear different colors of lipstick...hence the name rainbow.
961441
Rainbows are always the same size.  The diameter of a rainbow is best expressed in degrees as it is not at a fixed distance away.  Rainbows can be thought of as occupying the surface of a thin cone with its pointy end at your eye, and the angle of the cone is fixed.  This angle depends only on the refractive index of water.\n\nYes - you can get one bigger than a semi-circle, but only if you get well above the earth's surface (perhaps in an aeroplane) so that the ground doesn't get in the way!
1156057
The arc is what YOU see. the truth is that it is a complete circle obscured by the horizon. The colors are not created by the raindrops (moisture droplets would be more accurate) but by the angle the light is shining through them. it is a relative thing as well meaning the view or lack of depends on your perspective. No matter how scientifically I describe this; a rainbow is an amazing thing and I hope you enjoy every one you see!
448202
If you shine a white light through a prism, the light is refracted and you get a rainbow. Thats how you can see the different wavelengths in white light.
122346
Why don't you search the answers to the previously posted questions here on this topic? This has been asked over and over. \n\nHere is a little bit to get you started:\n\nRainbows are caused because the different colors in white light are bent by different amounts in rain drops, so the colors get separated. The sun shines from behind the observer, and then bounces off the back surface of the raindrops, and those raindrops that are at the required position for light to reach the observer from the sun contribute to the rainbow. This arc is formed by the collection of raindrops which are at the vertices of angles of 42 degrees between the observer and the sun.
335678
It's an acronym that is used to remember the colors in the rainbow.\nRed\nOrange\nYellow\nGreen \nBlue\nIndigo\nViolet
93248
At the end of the rainbow