Why do cairn terriers, and for that matter, all terriers, LICK THE AIR???????????????

I think this would be most dogs. dogsd are scent oriented, and they are literally tasting the air. Males will also lick the ground where a bitch has weed and grind their teeth, and smack their lips, in a characteristic manner.

Also to see their noses girating on a frosty morning is quite something. Mine are very nose oriented, and do a lot of Air scenting, it is a breed characteristic.