Still Water

I accidentally left a glass of cold water overnight. In the morning, I was surprised to see many air bubbles clinging inside the glass wall.

Curious, I search & got the answers. But if you are lazy to read through the more scientific explanation, here is a short answer:-
When you draw a glass of cold water from your faucet and allow it to warm to room temperature, nitrogen and oxygen slowly come out of solution, with tiny bubbles forming and coalescing at sites of microscopic imperfections on the glass.

Rick Watling, a meteorologist with the National Oceanic and Atmospheric Administration, offers this explanation.
Why do bubbles form if a glass of water is left alone for a while?

Another answer went as far as explaining why gushing hot water looks milky! Hmmm ... interesting.
Water Chemistry

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