It's actually blue,green,and purple that are cool colors. Throughout history red, orange, and yellow, were colors that were assigned to warmer colors because of fire, or the way it affected livings things emotions. When blue is used in a painting as the main color, most people express feelings of sadness from the painting, where as warmer colors express tropical or happy feelings... also temperature is included. Just like fires, ice is usualy seen as blue because of the colors of the sea or water that is frozen. Check out color theory and the way they are placed in a circle shape.