This is a combination keg/carbonation/beer storage question.
I have only fridge/freezer room for either a carboy or my (currently 1) keg.
I have about half of the corny keg left of a light cream ale, and had to boot it out of my fridge to put in an IPA for a couple/3 week cycle. It was properly carbonated (seemed to work great at 11ish PSI) before I pulled it out and am keeping in a 75ish degree room.
For fun (and science!) I drew a glass off of it yesterday and it was all foam and then flat [tasting] beer under it.
So, my questions, in "teach a man to fish" style (and assuming there are no leaks in my system, which I believe to be true):
1) what is the phenomenon that changes how the carbonation level of the beer appears when it is at room temperature? In my mind, I think of a carbonated beer as having bubbles suspended in the liquid once the container is properly pressurized. i.e. a headspace of CO2 that is of sufficient pressure to keep the CO2 suspended in the beer. When dispensing, the pressure equalizes again to maintain that pressure. It's hard for me to visualize how the beer could come out "flat" looking if the pressure level of the system hasn't changed. Note, I turned off the CO2 when I took it into room temperature, as it seemed like the right thing to do(?).
Now, at room temp CO2 expands I believe (?), but why exactly did that result in what I observed? I think if I understand that, I'll understand much more about the process.
2) Given #1, and knowing that the beer style matters as far as how it ages, what would you target as a general rule/deadline to get it cold again?
3) Given #1 and #2, should I purge the keg while it is warm and sitting until it's cold again? If so, why?
I know that's a mouthful (or 3), but I feel like I'll understand much more and be able to fish (and drink) if I get these concepts nailed down :)
Thanks! (And as always, if you have articles or chapters of books you'd point to, I'd love those as well/alternately).
(This is brew #4, so surely I'll start to run out of questions soon...)