The visible atmosphere is called the aura. Those who do not feel its vibrations sometimes see it in the form of colors or light. There are some quite unevolved people who see auras for the same reason that some very unevolved people also communicate with spirits, which is really something that only an evolved person should venture upon. But they are made like that by nature, and it is the same as someone who has never been trained in the technique of art yet he draws a beautiful picture. It is in the person, it is a gift, it is his finer soul and his nervous temperament that are susceptible to finer vibrations.