This simple question should have only one real answer although I've seen so many different answers.
In the beginning of my brewing career I knew I didn't know. Then I read about it and brewed some beer and then I knew. Now I am unsure again and before I pass on my knowledge about this I want to be sure which is true:
The difference between bottom fermented and top fermented beer refers to
1. the temperature range in which the beer has been fermented
2. in top fermented beers the yeast will rise to the top of the beer - in bottom fermented beers it will drop to the bottom.
3. both 1 AND 2
4. something completely different
The reason why I have doubts is that professional brewery sites state #2 is the correct answer. My own take is #1 since the bottom fermented pilsner I made once had a layer of yeast on top during fermentation (cause of the co2 release) and it all dropped to the bottom at the end of fermentation. Exactly as my top fermented ales.
I am asking you for valid solid proven true information - not what you think you know. Anyone?