Presented here is color as researched by Goethe1).
Yellow and blue form the basis of all colors/emotions in this color wheel.
A colored fluid in either of those base colors will intensify differently in appearance depending on the depth of the fluid as illustrated by the filled staircases: Yellow intensifies towards red and blue(cyan) intensifies towards violet.
Yellow to red is associated with the emotional properties of light and warmth.
Blue to violet is associated with the emotional properties of darkness and cold.
Colors opposite of each other in the wheel are called complementary colors which, if mixed, cancel each other out to produce an achromatic appearance.
These perceptual concepts of colors differ from the scientific color theory which is fully independent of human interpretation and the attribution of basic emotions.