Cool Sirocco Sky

Old English cōl, of low temperature — used as a color modifier as the complement to warm. Cool gray, cool blue: the optical impression of a slight blue-green shift, even within otherwise warm or neutral hues. Sits across the crisp, hushed, pale, and neutral buckets.

Arabic sharq, eastern-or-Saharan-wind. As a color modifier, sirocco implies a hot-Saharan-and-Mediterranean-wind quality, the visual register of Saharan-and-Sicilian-and-Maltese-sirocco hand-hot-Saharan-and-Mediterranean-wind Saharan-and-Sicilian-and-Maltese-sirocco-and-North-African sirocco-and-hot-Saharan-and-Mediterranean-wind surfaces under Saharan-and-Sicilian-and-Maltese-sirocco-and-North-African Sahara-and-Sicily-and-Malta-and-Tunis hot-North-African-wind-light. Sits at the modifier-and-weather end of the grid, parallel to mistral and zephyr 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.