Chromatics: Warm and Cool

Abstract Artistically, an important bipartition of hues is with respect to their warm–cool quality. What might this correspond to in colorimetric terms? Various interpretations have been suggested, mostly informally. We attempt to compare them quantitatively, using either diverse data available from the literature, or formal means. We conclude that it is not possible to differentiate between various ontologically distinct interpretations. The warm–cool axis is roughly aligned with the Orange–Teal axis of the color circle. Leeway is about two steps either way for a 24-step division. Within this margin, virtually all suggested meanings pertain. The dominance of this axis in nature is due to generic physical properties.