Normal freezing occurs when the atoms of the container walls impose an ordering on the liquid atoms causing them to arrange themselves into a crystalline structure and begin to grow. Without the container, the onset of freezing (called nucleation) has a good chance of not happening. But, at some lower temperature nucleation will occur and very rapid freezing takes place (called recalescence).
Curator:Tom Rathz/UAH tom.rathz@msfc.nasa.gov