Warm Down Sky

Old English wearm, of moderate heat — used as a color modifier since the medieval period for hues that read as containing red, orange, or yellow undertones. Warm gray, warm white: not necessarily a temperature, but the optical impression of a slight red-orange shift. Sits across the crisp and neutral buckets.

Old Norse dúnn, down / soft-feather. As a color modifier, down implies a soft-feather-undercoat quality, the visual register of eider-and-goose-down hand-plucked-and-cleaned eider-and-goose-down soft-feather-undercoat surfaces under eider-and-goose-down hand-plucked-and-cleaned bedding-and-cushion light. Sits at the modifier-and-texture end of the grid, parallel to fluff and fur 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.