Sea and Sky
One of the reasons that the sky and the sea appear blue because both air and water scatter short wavelength light more than longer wavelengths, (Rayleighs scattering). Blue light is at the short wavelength end of the visible spectrum, it is more strongly scattered in the atmosphere than long wavelength red light. According to info on Wickipedia (mmm…) the colour perceived for the sky is similar to that obtained by a monochromatic blue of wavelength 474–476 nm (nanometers). There are other reasons that effect the blueness of the sky and sea, particularly the sea reflecting the colour of the sky. I’ve been documenting the sky and sea when it’s overcast and grey and the sea and sky are almost one and the horizon is not defined and ambiguous. http://www.stigevansphotography.co.uk/offings/
I have also been colour matching Dulux household swatches to the landscape. It works best when you have a large area of monochromatic colour, a cloudless sky being ideal. I started 2 years ago doing these (a process that emerged from the ‘Colour Library’ from my last residency at Fabrica). I’ve found that only a few of the swatches really match, where as I would have thought there would be a bigger variety of swatches that worked, depending on geography and where you placed them in the sky, I have matched skies in Italy, France, North Africa and here in the UK. “Saphire Springs” seems to be the best for the intense blue you get high up in a clear sky, “Atlantic Surf” is good for nearer the horizon where its a paler blue. Surprisingly or maybe not ,”Venetian Crystal” seemed to be good for Italy, although I was near Rome. “Royal Regatta’ performed well in south west France.
What I’m going to do very soon is take the readings of those blue (sky) swatches that i’ve matched and using a spectrophotometer, that measures wavelengths see if they are near wavelength 474–476 nm that wickipedia says is the colour of the sky.