Etched Era Sky

German ätzen, to etch — past-participle of etch. As a color modifier, etched implies a clear-and-precisely-incised quality, the crisp color of Rembrandt-and-Dürer hand-pulled etching-print fine-line incised-image. Sits at the crisp-and-incised end of the grid, parallel to engraved and inscribed in usage.

Latin aera, epoch. As a color modifier, era implies a period-and-historical-epoch quality, the visual register of historical-period-and-epoch multi-decade period-correct epoch-marked-and-defining-period surfaces under historical-period epoch-defining mood-and-light. Sits at the modifier-and-time end of the grid, parallel to age and cycle 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.