I <nodding in understanding> am a nail biter. My tauma is self induced, although minimized through years of practice. I do see a variance in the pattern as my habit fluctuates, so I am inclined to believe the 'trauma' hypothesis.
Regarding the white part of the nail, near the cuticle, these are called lunule(s) or lunulae to be technically correct (like the moon). They are caused by new nail cells that have not lost their fat content, ie - dried out. (I cant find the web page that showed me that - sorry). My lunulae have increased as my cuticle habit increased I noticed. Perhaps the tissue damage exposes the new cells too soon. As for calcium or air pockets,etc, I have seen no "technical evidence", but as always, many factors can affect the situation. (I'll begrudgingly shut up now. Hmph)