Spectral Bark 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 Norse bǫrkr, bark. As a color modifier, bark implies a tree-bark-and-rough-and-cork quality, the visual register of birch-and-oak-and-cork-bark hand-stripped-and-cork-bark birch-and-oak-and-cork-tree-bark hand-stripped-tree-bark surfaces under birch-and-oak-and-cork-bark hand-stripped-bark forest light. Sits at the modifier-and-texture end of the grid, parallel to rough and cane 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.