THE NOTION OF COLOUR TEMPERATURE is both instinctual and cultural, developing from our experiences of red-hot metal and blue glacial ice. While the primary red and blue on our hot and cold taps belong to unequivocally opposing categories of colour temperature, other colours in the spectrum hold more ambiguous positions. Attempts to bisect the colour wheel and separate it into objectively warm colours and cool colours ultimately fail because warm and cool should be seen as relative directions around the wheel, not a fundamental property of a colour.
If we treat orange-red as our warmest colour and cyan-blue as our coolest then we can describe the temperature of a colour by
