Originally Posted by
foldedpath
... One of the distinguishing features of an air for me, at least in the Irish/Scottish context, is that you can't tap your foot to it.
An air has "rubato" phrasing; varying tempo for emotional expression, as with John Kelly's example above, or the Sean Nós clip linked by jesserules ...
Another difference is that, at least in the Irish/Scottish tradition, an "air" would usually be a solo performance, and not something a group would play together ... A "slow air" with metered tempo, or a true slow air that's been crammed into a 3/4 or 4/4 tempo -- as "Da Slockit Light" is often played in sessions -- is more successful as a group effort, because everyone is on the same rhythm train.