okay, I've been trying to figure this one out for a while—an approximate mapping of "classical elemental" concepts into physical terms. and I think I've arrived at a tentative formulation. it's like four different ways that molecules can choose to interact with each other.
earthiness means settling down next to each other in solid lattices or structures
wateriness means molecules moving around but remaining in close association with each other
airiness means molecules freely moving as individuals through space but not interacting each other chemically
fieriness means molecules interacting with each other and being changed
~Chara