Usually the situation where the skirt is folded,crumpled or tucked up or in a way that it is able to hold its position on its own, without having the user to maintain it in place. If the wearer needs to be holding the garment, then that would mean a skirt_lift, and not a skirt rise. The most basic situation is that of a pencil skirt, or mini skirt that begins to ride up, or was purposely folded up.
skirt rise