Comparing for Colour Temperature

The practical colour wheel's fifth use is for colour temperature recognition.

Practical Colour Wheel

Not only is the wheel a colour - value reference, it is arranged so the warm colours are on the left and the cools are on the right side (warm up, cool down).  This is very valuable information when you are comparing shapes for colour and asking "is this shape warmer or cooler than that shape"?  For example, if you have a shape in the cool that is as you see it - painted as ultramarine, and the shape you are comparing to it is warmer, but still in the cools, then you know which way to go on the colour wheel to paint the new shape.  So you know which colours are cool, which are warm, and within either cool or warm you know which colours are relatively warmer or cooler.  Ultramarine is cooler than cobalt blue or cerulean, and cadmium red light is warmer than cad red middle which is warmer than alizarin.  This helps when coming to light - go up the colour wheel and add a touch of white (remember that white is the coolest on your palette and it will cool the colour it is mixed with).