Defined Gemini Sky

Latin dēfīnīre, to set bounds — past-participle of define. As a color modifier, defined implies a clear-and-edge-distinct-and-precise quality where the hue carries the visual register of sharp-bounded-and-clearly-delimited surface. Sits at the crisp-and-clear end of the grid, parallel to crisp and sharp in usage.

Latin gemini, twins-of-the-zodiac. As a color modifier, gemini implies a twins-and-air-sign-and-Mercury-ruled-mutable-air quality, the visual register of Castor-and-Pollux-Gemini-twins hand-twins-and-air-sign-and-Mercury-ruled-mutable-air Castor-and-Pollux-Gemini-twins-and-Argonaut-twins gemini-and-twins-and-air-sign surfaces under Castor-and-Pollux-Gemini-twins-and-Argonaut-twins late-spring-and-May-and-June mutable-air-sign-light. Sits at the modifier-and-zodiac end of the grid, parallel to castor and pollux 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.