Supercooled Water - Explained!
Why Physics Stack Exchange recommends it
Physics Stack Exchange users link it when explaining or referencing supercooled water and nucleation in questions about water that stays liquid below 0 \u00b0C and then freezes suddenly.
Recommended by 1 people across 1 different months, 2021 to 2025.
What it is
A short Veritasium explainer on supercooled water, the effect behind videos of bottles that freeze almost instantly when tapped or poured. It shows how to replicate the experiment at home and explains the role of nucleation sites, using molecular illustrations from PhET simulations.
What people said
Recommends Philip · 2021-04 · Physics Stack Exchange · on “Why was water freezing almost instantaneously when shaking a bottle that spent the night outside during a frosty night?”
Congratulations, it sounds to me like you've just observed supercooled water [LINK] ! There are many videos on YouTube that describe this phenomenon, and explain it much better than I could, see here [this video] for a Veritasum video where this is discussed for example. The basic idea is this: when water freezes it forms ice, which is a nice regular crystalline structure. However, ice-crystals need a nucleation site , which is a point where the crystal can start to form, before they can actually start to form. In normal situations, water usually has some impurities which can serve as such nucleation sites, around which the crystal starts to grow and ice starts to form. However, if you use very p
Cites Farcher · 2022-12 · Physics Stack Exchange · on “Why doesn't 250 ml of tap water kept outdoor in -2 °C freeze to ice?”
As it is tap water it might not be pure enough to become supercooled [this video] or impure enough to cause a significant depression of freezing point. [LINK] That being so it might be that the ground on which the beaker is standing has enough of a thermal capacity to maintain the water in the liquid state. That is, the ground on which the plastic container stands provides enough heat to keep the water temperature above freezing. As a further part of your investigation I would measure the temperature of the water and of the surrounding air in the early morning before the ambient temperature rises above $0^\circ \rm C$ . If the plastic container is elevated above the surrounding ground then the ai
Cites Rich · 2025-08 · Physics Stack Exchange · on “Latent heat and instant freezing of super-cooled water”
Super-cooled water: There are many videos on youtube showing bottles of super-cooled water freezing instantly when tapped, like this one [this video] or forming little stalagmites of ice when poured out. There seems to me to be a problem. The super-cooled water is at about $-20^\circ$ C and water freezes at $0^\circ$ C. But to freeze, its latent heat has to be removed. Latent heat of water is $334\,$ kJ/kg, specific heat capacity of water at $0^\circ$ C is $4.22\,$ kJ/(kg K). One kg of water can absorb $84.2\,$ kJ when warming from $-20^\circ$ C to $0^{\circ}\text{C}$ , but needs $334\,$ kJ removed to freeze. None of the youtube videos I watched go into this point. The answer to this question doe