From my childhood till now, I have been wondering about the "pink", or sometimes "magenta" color of the evening sky. According to the scattering of light phenomenon, the colors pink/magenta do not directly appear in the spectrum. Moreover, it is said that pink appears as a result of red+white. Do these colors mix somewhere in the sky? Please explain the appearance of sky colors other than blue, red, yellow.
The misconception that pink isn't technically a colour is absurd, really. Pink is just as much a colour as any other colour in the visible spectrum (not that your perception of the colour validates it, but that it can be measured and that measurement is reliable and repeatable).
The mixing of the colours happens in the atmosphere. The colour pink arises when the necessary components to make the pink light are simultaneously scattered by the molecules in the upper atmosphere. By mixing, I mean the superposition of multiple wavelengths that combine to create the wavelength perceived by our brains as pink light.
You are right, magenta doesn't exist as a wavelength: it's a result of mixing violet (the shortest wavelengths of visible light) and red (the longest) - in theory the colour we should see should be somewhere around green but for some reason our brain mixes the two and sees magenta.