Heartening Yule Sky

Old English heorte (heart) — present-participle of hearten. As a color modifier, heartening implies a clear-and-uplifting-and-encouraging quality where the hue carries the visual register of cheerful-encouraging color-tone. Sits at the crisp-and-cheerful end of the grid, parallel to welcoming and cheerful in usage.

Old Norse jól, winter-solstice. As a color modifier, yule implies a winter-solstice-and-fir-tree quality, the visual register of Norse-and-English winter-solstice fir-and-holly-and-mistletoe candlelit-firelight feast-and-greenery surfaces under deep-winter Northern-Hemisphere late-December candlelight. Sits at the modifier-and-time end of the grid, parallel to advent and easter 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.