|MadSci Network: Physics|
The question is: "I know the sky's blue because only some wavelengths are scattered. But isn't green light scattered, too? (Most violet, I think, gets absorbed) And don't the green and blue of the rainbow add up to the cyan we see in the sky?" The answer: You are correct in your first question. We call the sky blue because that is the color that our eyes and brain interpret the broad spectrum of scattered light to be. The broad spectrum of scattered light has a broad peak in the region of wavelengths that we call blue. I'm not actually sure what you mean by your second question about the rainbow. The blue of the sky is certainly a result of scattered "white" light from the sun, and the colors of the rainbow also come from sunlight, but we obviously don't need a rainbow around in order to see blue sky!! If you mean that the cyan in the rainbow itself is a combination of blue and green then that is not quite correct, because the cyan color is itself a certain narrow range of wavelengths and would be there even if the blue and green were not. I hope this helps!! John Link MadSci Physicist
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