Then you may as well say there is no color, because technically speaking color is a physiological phenomena , between the color receptors in your eyes and the brain that processes the information.<quoted text>Yes- we say the sky "is" blue. Technically speaking, that is simply not correct.
What is correct is that the sky APPEARS/LOOKS blue, but in this case, what appears to be the case actually is not the case.
We call that chromatics. It's all illusion but for all intents the sky is sometimes blue, as surely as it is sometimes black.