Smooth Glass Sky

Old English smōþ, level, polished — used as a color modifier since the seventeenth century for hues that read as continuous without texture or break. Smooth tan, smooth gray: moderate saturation combined with optical evenness. Sits in the crisp-bucket alongside even.

Old English glæs, glass. As a color modifier, glass implies a transparent-and-vitreous quality, the visual register of Murano-and-Bohemian-glass hand-blown-and-cut crystal-and-leaded-glass Venetian-and-Bohemian glass-and-crystal surfaces under Murano-and-Bohemian-glass workshop-light. Sits at the modifier-and-texture end of the grid, parallel to gloss and shine in usage.

The blue of a clear sky at noon — produced by Rayleigh scattering, the preferential dispersion of shorter wavelengths through atmospheric molecules. Air itself is colorless; the color we see is sunlight scattered toward our eyes by every cubic kilometer above. The reference shade is mid-latitude noon under a high pressure system: a clean, slightly green-shifted blue with the luminous depth of light scattered across an entire hemisphere of air.