Spectral Lintel Sky

Latin spectrum, appearance — adjectival suffix -al. As a color modifier, spectral implies a saturated-and-rainbow-decomposed-and-pure quality, the bright color of Newton-prism sunlight-decomposed seven-color spectrum band. Sits at the bright-and-pure end of the grid, parallel to prismatic and pure in usage.

Old English lyn-trigan, threshold-beam. As a color modifier, lintel implies a horizontal-load-bearing-beam-above-door quality, the visual register of Stonehenge-and-medieval-stone-lintel hand-cut horizontal-load-bearing stone-and-timber lintel-above-door architectural surfaces under medieval-stone-and-timber lintel-above-door light. Sits at the modifier-and-architecture end of the grid, parallel to sill and truss 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.