Which color does Americans often use to express heat?

Many everyday American expressions are based on colors.
     Red is a hot color. Americans often use it to express heat. They may say they are red hot about something unfair. When they are red hot they are very angry about something.
     Pink is a lighter kind of red. People sometimes say they are in the pink when they are in good health.
     Blue is a cool color. Blues are slow, sad and soulful. Someone who is blue is very sad.
     The color green is natural for trees and grass. But it is an unnatural color for humans.  A person who has a sick feeling stomach may say she feels a little green. Sometimes a person may be upset because he does not have some- thing as nice as a friend has, like a fast new car. That person may say he is green with envy.
     The color black is used often in expressions. People describe a day in which everything goes wrong as a black day. The date of a major tragedy is remembered as a black day. In some cases, colors describe a situation.  A black out is an expression for a reduction in electric power. Black outs were common during World War Two. Officials would order all lights in a city turned off to make it difficult for enemy planes to find a target in the dark of night.