Changes in value are the primary means of shading objects to convey form. Warm and Cool Colors Colors such as red, yellow, and orange, that are associated with sunlight, excitement, and action, are called warm colors. Blue and blue-greens are associated with ice and water. These are called cool colors. Warm and cool are relative terms since a red may appear cool next to a bright orange.
Warm coolers appear warmer and cool colors appear cooler next their opposites in temperature.
An interesting optical property of warm and cool colors is that warm colored objects are perceived as being closer than cool objects. This important illusion is often exploited by visual artists. The Hue illustration above is an extreme example of this effect. Notice how the red areas appear to float in front of the cooler areas. Test - Form and Color 1.