The spectrum is often divided into two sets of hues based on the temperature commonly associated with the hues. This contrast has been called warm/cool contrast, contrast of temperature, or humidity contrast.

The two poles for warm/cool contrast are red orange (warm) and blue green (cool). The warm colors are considered to be yellow, yellow orange, red orange, red, and red violet. The cool colors are blue green, blue, and blue violet. Green and violet are considered to be intermediary colors that will be either warm or cool depending on the surrounding hues.

EFFECTS OF COOL/WARM CONTRAST

Color can actually have effects on observers in different ways.
1. On a physiological level, the eye perceives warmer colors as being brighter, lighter, and forward of equal value/intensity cool hues.

2. Warm colors can have the effect of physically causing body temperatures to rise. Cool colors can have the opposite effect and lower respiration rates.

3. Color can have an effect on the psychological level as well. Cool colors can have a calming effect while hot colors tend to make a viewer feel agitated and hot.

SPATIAL EFFECTS

The spatial effects of warm/cool contrast are the result of the perception of color and associations of colors to atmospheric perspective. Warm colors are normally interpreted as being forward on the picture plane while cool tones are perceived as being distant.

The contrast of intensity can override the spatial effects of cool/warm contrast.