Air bazooka + fog machine = cool cloud rings

Its fun to play with Airbazookas for sure....Blow air with speed that can move hair or even drop a small target from certain distance. Now imagine filling the Airbazooka with fog from a fog machine and you see cool cloud rings (smoke rings) coming out at quite a speed.

What's happening?  How do these smoke rings form?

A smoke ring forms when a puff of smoke is suddenly blown through a narrow opening.  It works best if the outer air is still (i.e. not windy).  In the still air, the outer part of the puff of smoke gets slowed down compared to the core of the puff which makes it look like a ring.  If the air around is quite still, these rings can travel quite a distance maintaining their shape.  

These rings will form even with just blowing puffs of air but the rings are not visible.  With smoke or fog (from the fog machine), these rings are visible quite well.