Plain Tao Sky

Latin planus, flat, level — used as a color modifier since the medieval period for hues that read as undecorated and direct. Plain white, plain blue: moderate saturation, no shift, no surface effect. Sits in the crisp-bucket center, with the implication of restraint rather than absence.

Chinese 道, the-Way. As a color modifier, tao implies a Daoist-and-naturalistic quality, the visual register of Chinese-Daoist-Wǔdāng-Mountain Daoist hand-built rock-and-pine-tree-and-incense-burner mountain-temple surfaces under Wǔdāng-Mountain-and-Mount-Hua Daoist-mountain-temple mist-and-pine light. Sits at the modifier-and-cultural end of the grid, parallel to zen and sufi 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.