Plumb Lux Sky

Latin plumbum, lead — referring to the lead-weighted plumb-line of pre-modern carpentry. As a color modifier, plumb implies a clear-and-vertical-true quality where the hue carries the visual register of gravity-aligned-and-perfectly-vertical surface. Sits at the crisp-and-balanced end of the grid, parallel to level and squared in usage.

Latin lux, light. As a color modifier, lux implies a Latin-light-and-Fiat-Lux-and-Lux-Aeterna quality, the visual register of Genesis-Fiat-Lux-and-Lux-Aeterna hand-Latin-light-and-Fiat-Lux-and-Lux-Aeterna Genesis-Fiat-Lux-and-Lux-Aeterna-and-Requiem-mass lux-and-Latin-light-and-Fiat-Lux surfaces under Genesis-Fiat-Lux-and-Lux-Aeterna-and-Requiem-mass Vulgate-and-Tridentine-Mass primal-light. Sits at the modifier-and-Latin end of the grid, parallel to ignis and opus 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.