Smooth Swoop Sky

Old English smōþ, level, polished — used as a color modifier since the seventeenth century for hues that read as continuous without texture or break. Smooth tan, smooth gray: moderate saturation combined with optical evenness. Sits in the crisp-bucket alongside even.

Old English swāpan, to-sweep-down. As a color modifier, swoop implies a fast-descending-and-arcing-down quality, the visual register of peregrine-falcon-and-stooping-hawk-swoop hand-fast-descending-and-arcing-down peregrine-falcon-and-stooping-hawk-and-eagle swooped-and-fast-descending-and-arcing-down surfaces under peregrine-falcon-and-stooping-hawk-and-eagle cliff-face-and-moorland-and-open-sky raptor-stoop-light. Sits at the modifier-and-mood end of the grid, parallel to flit and glide 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.