Sounds a lot like the way I grew up. My father is b-polar, so he can go from a good mood to a bad one in seconds. He will be fine, then all of a sudden start yelling about anything, then later act like nothing happened - no appologies.
I am not saying that your mother is BP, but there is obviously a reason she can't control the anger when it gets to the point of yelling at you for no reason & then later acting as if nothing happened. Esp if this has alway gone on that you remember, then there is nothing YOU can do to change her behavior. She is an adult, she needs to recognize that she's got a problem that she needs to get a hold of & find a way to change that. If she doesn't recognize it & even if you try to tell her & she still doesn't see it, then things most likely won't get better.
I am sorry you have to go thru this, I know how bad it is b/c I have been there. Things didn't get better, sadly, till my parents separated & my father left the house when I was 17. Now I'm 21, they are divorced & it's still not better... but I choose not to deal with my father b/c he has mental issues that he chooses not to address & I can't handle the kind of person he is without him getting help. But hopefully things will work out different with your mother & she will find the help that she needs to overcome this.