Heyas. Recently my brother showed me a trick with a plastic bottle of very cold water. It was out of the freezer, pretty cold, but not frozen. He took the bottle and slammed it against the counter and the bottle froze up. I'm at a loss for explaining why this happens.. The only thing I can think of is when its slammed air is escaping the P decreases, allowing T to decrease allowing some of the particles to crystalise. Anyone else got an idea?