Matt,
If you lift the wand from the surface your working on you will lose suction, yes it will increase airflow dragged in from outside the wand and create a vortex.
Example, if you create a seal with your lips over the back of your hand and suck air inwards, you will create a vacuum.
Now try it again slightly lifting your lower lip away from the back of your hand, you will of noticed a loss of vacuum.
Please don't think I sit here all day sucking the back of my hands.
Regards,
Fletch.