Air is one of the five elemental rings.
Dynasty and Conflict Cards
Air is a trait that can appear on shugenja and spell cards.
Province Cards
Air is one of the elemental types that a province can have.
Roles
Air is the element of two roles that a Clan can have. Those roles are Keeper of Air (currently unassigned) and Seeker of Air (currently assigned to the Crane Clan).
Trivia
The Book of Five Rings calls the ring Wind, not Air.