The Physics of Snapping Fingers

There are three components to the snapping finger sound:
(1) The “friction” or “sliding” sound between the second (middle) finger and the thumb.
(2) The “impact” sound from the collision of the middle finger onto the third(ring) finger and
(3) The “pop” sound from the rapid compression and subsequent decompression of air, as a consequence of the middle finger’s impact to the palm.This is the most audible of the three.

In order to get the full “snap” sound, the fast-moving second finger must hit both the palm and a small portion of the third finger. If it hits only the palm or the third finger, there will be a significant reduction in the total ‘snap’ sound.

I would strongly suggest that you stop at this juncture and spend some time exploring the finger snap. Only if you arrive at these conclusions independently would you be able to truly marvel at the underlying physics.