A while ago Timothy Ferguson did a podcast on the Natural Qualities of Aquam, so as to define what the unnatural qualities of water might be. It occurs to me that discussions of the natural qualities of the other elements could be useful. So, starting with Auram:
Air is, according to Empedocles, Plato, and Aristotle:
Levitate: Denser than Fire, Lighter than Water
Mobile, which I conclude means both fluid and active
Sharp: I am not sure what this means in this context
Smooth, as in the atoms of air are so smooth they can barely be felt (Plato)
I reject that air is hot or wet, as there are cold dry winds, although I can accept that air is inclined to be hot and wet; it is receptive to heat and moisture. Indeed, air seems to be receptive to the other elements, a vessel of the elements and relatively yielding. This quality seems essential to animal life: air is breathed in, takes up the heat of the body, and carries the heat away, to allow bodies to maintain a balance of hot and cold. Air also seems to be receptive to spiritual power, as in the Breath of Life.
Air is denser than fire and lighter than water: Air has levitas, as opposed to Earth and Water, which have gravitas. It has more levitas when warm and dry than when cold and wet, and seeks to achieve a balance of these state qualities.
Air is mobile, which I understand to be fluid. Air is also expansive - it fills any container and overflows any open container. Air is also penetrating, which seems to simply be a function of its fluidity. Air can seep through tiny holes and is thus penetrating.
Air is also quite strong, deceptively strong, as can be shown in great winds and gales.
Something the ancient philosophers did not seem to remark on: natural air is relatively transparent. Exceptions to this seem to involve mixtures of elements: Fog and clouds are air holding water, either receiving or dispensing; smoke is the fine powder of ash.
Other qualities? I've generally stayed away from emotional and spiritual qualities here.
If this is an interesting discussion, I'll try to follow through with all of the Elements, and possibly on the the rest of the Forms.