What are the small bubbles that form in a glass of water? © Getty Images

What are the small bubbles that form in a glass of water?

Ever found yourself wondering why there is always the odd bubble floating around the glass, even though you poured still water?

Asked by: Bob Bullock, Swansea

Advertisement

Water contains dissolved air, molecules of which accumulate around tiny imperfections on the glass. This process of “nucleation” continues until a bubble forms, breaks free and rises to the surface. Dropping something light but crinkly like a lemon pip into fizzy water can trigger repeated cycles of nucleation and bubble formation, making it rise and fall repeatedly.


Advertisement

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.