It has nothing to do with the physical or symbol of the sign. Air, water, fire, and earth are more so about the way people think and carry themselves, like water signs are more emotional people. They feel things strongly. earth signs deal with logic and analyzing things, and they aren't really emotional. Fire deals with spontaneous behavior, like showing out and being in your face. Air signs deal with thinking outside the box and having unconventional or "weird" thoughts and doings, etc.
