rainbow has predetermined colour pattern display.  is the radius constant & why ?
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freepatentsonline.com/6710919.html
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Each pixel on the screen is composed of three colours (red, green, blue) that each vary in intensity and blend together to give the illusion of one pixel colour due to their small size.\nWhen a drop of water lands on the screen, it magnifies the individual pixel colours such that they appear to be distinct.
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Rainbows are caused by sunlight reflecting off and refracting through raindrops. There is a very specific angle that each different wavelength of light will take so all parts of the rainbow of that color are always seen at exactly that angle away from the Sun, about 42 degrees for visible light. In math, the collection of all points at a certain distance from a point is a circle, so rainbows are seen as a circle around the sun.
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This site might help "see" what is going on and why.  Interesting question by the way.  I saw my first one last summer and the colors were so bright.  It was amazing!  Had everyone out in the parking lot of the strip mall checking it out.\n\n\nhttp://hyperphysics.phy-astr.gsu.edu/Hbase/atmos/rbowpri.html\n\nhttp://en.wikipedia.org/wiki/Rainbow
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There is no gold at the end of a rainbow.\n\n\nThe traditional description of the rainbow is that it is made up of seven colors - red, orange, yellow, green, blue, indigo, and violet. Actually, the rainbow is a whole continuum of colors from red to violet and even beyond the colors that the eye can see.\nThe colors of the rainbow arise from two basic facts:\n\nSunlight is made up of the whole range of colors that the eye can detect. The range of sunlight colors, when combined, looks white to the eye. This property of sunlight was first demonstrated by Sir Isaac Newton in 1666.\nLight of different colors is refracted by different amounts when it passes from one medium (air, for example) into another (water or glass, for example).\nDescartes and Willebrord Snell had determined how a ray of light is bent, or refracted, as it traverses regions of different densities, such as air and water. When the light paths through a raindrop are traced for red and blue light, one finds that the angle of deviation is different for the two colors because blue light is bent or refracted more than is the red
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http://eo.ucar.edu/rainbows/\n\nThe traditional description of the rainbow is that it is made up of seven colors - red, orange, yellow, green, blue, indigo, and violet. Actually, the rainbow is a whole continuum of colors from red to violet and even beyond the colors that the eye can see.\n\nSunlight is made up of the whole range of colors that the eye can detect. The range of sunlight colors, when combined, looks white to the eye. This property of sunlight was first demonstrated by Sir Isaac Newton in 1666. \nLight of different colors is refracted by different amounts when it passes from one medium (air, for example) into another (water or glass, for example
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An inverse rainbow is when the colors are reversed so that the red band of color is on the inside of the rainbow and the blue band is on the outside.  Moonbows, or, halos, are inversed. I wasn't aware that rainbows were different here and there. If they are, my guess is the explanation would be found in optics and, maybe bioelectric fields stuff? Here's a GREAT website for future reference and to put in your Favorites file.  Just click on any "circle" of science and follow the algorithm. Handy little tool. Can't wait to come back and read if someone has an explanation.\nhttp://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
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In order to see a rainbow, you need a rather low source of light behind you and a layer of droplets in the air before you, which can be rain or spray.\n\nThe effect is similar to a prism breaking the light.  The exact mechanism is explained in the Wikipedia article below.
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Its all to do with the reflection orf light on concave and convex mirrored surfaces.\n\nSee this web page app. half way down for a more detailed explanation.\n\nhttp://www.mic-d.com/curriculum/lightandcolor/reflection.html
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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 :)
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Well I think they appear as lines; fat, multicolored, curved lines.  But they aren't really "there" where we see them.  That is, other people, say a mile away from you, will see the rainbow shifted from where you see it, and that's because the rainbow's apparent direction is relative to the sun's rays that are near you.  But is this the answer to your question?  Are you asking why they're not thin? straight?  Give us something, Bea.
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D) .diffraction grating, will split the light on the edges causing a rainbow effect on the edges of the objects
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Because it is refracting light that is coming from all around. When you see a rainbow produced by a prism it looks straight but if you were able to enlarge it enough it would be round.
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on some machines, the transparency doesn't work with the background-color\ntry it with just background.\n\nbackground: transparent;
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The only reason color exists is because objects (rain drops in this case) reflect certain wavelengths and obsorb certain wavelengths of light.  The only reason we see the colors in the rainbows is because the sun produces white light which, when refracted, will produce ALL OF THE POSSIBLE COLORS.  This is interesting, you will notice there is no brown in the spectrum (or rainbow); therefore, brown is not a color.  The sun doesn't have the same color as the rainbow, the rainbow has the same color as the sun.
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rgb is represented decimally like this:\n###,###,###\neach three # represent a value between '0 & 255' representing how much Red, Green & Blue are in the color, respectively,\nthis needs one byte to represent binary, so, say red is:\n'255,0,0'\nso in binary this is '111111110000000000000000'\nin hexa is FF0000\ngot the picture?
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Well supposedly, it'd be a brighter white color, but 256 is really all the bright it goes.\n\nHow it works is that your monitor (probably) has many thousand things called pixels. Each pixel is a red light, a green light, and a blue light. When you set an rgb, you're setting how bright each of the lights in the pixel is, and they combine to make a color. Of course, when you mix all the lights, you get white. So if you set them to 999 (which is impossible on monitors, I think), it'd just be a brighter white.