Clear Slick Sky

From the Latin clarus, bright, distinct — used as a color modifier since the medieval period for hues without haze or mixing. Clear blue sky, clear green water: the implication is moderate saturation combined with optical clarity. Sits at the crisp-bucket center alongside clean and true.

Old Norse slíkr, slick / smooth. As a color modifier, slick implies a wet-and-glossy quality, the visual register of oil-and-water-slick wet-and-glossy oil-and-water-slick reflective-surface slick-and-glossy-and-reflective surfaces under wet-oil-and-water-slick reflective-light. Sits at the modifier-and-texture end of the grid, parallel to sleek and gloss 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.