Heartening Throb 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.

Middle English throbben, to-beat-strongly. As a color modifier, throb implies a pulsing-and-beating-and-rhythmic quality, the visual register of racing-pulse-and-temple-throb hand-pulsing-and-beating-and-rhythmic racing-pulse-and-temple-throb-and-heartbeat throbbed-and-pulsing-and-beating-and-rhythmic surfaces under racing-pulse-and-temple-throb-and-heartbeat fevered-and-quickened-and-rhythmic candlelit-bedside-light. Sits at the modifier-and-mood end of the grid, parallel to pang and pulse 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.