According to the Chroma Theorists, colors are the result of temperatures in a given environment interacting with human emotions. Red is hot, blue is cold, and yellow is "meh."
But what about the colors that defy the rules? Like Neon? They're the rebels of the color world, refusing to be tied down by conventional thermodynamics.
Here's a rough estimate of the color-temperature continuum, based on the Color-Temperature Chart: