Crisp Glen Sky

Latin crispus, curled — drifted in English from the curled hair sense to fresh and clean. As a color modifier, crisp implies saturation combined with optical clarity, with no haze or film between the eye and the surface. Used across the bright and crisp buckets where the hue is fresh-looking. Slightly less assertive than vivid.

Scottish-Gaelic gleann, narrow valley between hills. As a color modifier, glen implies a sheltered-and-mossy quality, the visual register of Scottish-Highland deep-cut river-valleys with peat-water-and-bracken hand-cut shieling-and-bothy crofting-life surfaces under Highland-and-overcast sky. Sits at the modifier-and-place end of the grid, parallel to vale and dell 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.