Harry Potter and the Prisoner of Azkaban - Fogged Bottle
In the scene where the train is on its way to Hogwarts, it gets stopped by the dementor things. The window and bottle in Harry's cabin get fogged. Why didn't his glasses get fogged? They should have. I wear glasses so I should know.
It's because the window has water on it so it freezes and the bottle has liquid in it so it does too. As for Harry's glasses they don't have any liquid on them so they don't freeze.