different sized bubbles

[dragonbiker]

Okay, we're gettin down to the gnat's ass here. Some of my favorite beers have different sized bubbles. Guiness has very small tight bubbles, fat tire has small bubbles, low carbonation, some pilsners a like have big bubbles.

How is this done? The amount of priming sugar? Different kinds of priming media? Does the final gravity of a beer affect bubble size?

All opinions are welcome.

[jaydub]

One of the reasons Guiness has such different looking carbonation is that its frequently (always?) done with nitrogen rather than carbon dioxide. Surface tension has everything to do with bubble size as well, and I imagine that the difference in "body" between a stout and a pilsner (or megaswill for that matter) might effect how the effervescence operates.

[rich]

When CO2 or Nitrogen precipitates from solution it must do so from a nucleation site, i.e, flaw in the glass, minute scratch, particle in the beer. As the bubble rises, it becomes a nucleation node itself, gathering more gas to itself... Well, I not a chemist, but this guy is. Here's a good artical on the "fizzics of beer".
Fizzics of Beer