Water freezing is one of the most common yet most magical phase transition processes in nature. When water temperature drops to its freezing point (0°C) and continues to dissipate heat, the thermal motion of water molecules slows down. They begin to break free from the random flow of the liquid state and arrange themselves in an orderly fashion according to the hexagonal crystal system, forming solid ice. This process is not instantaneous; it begins with a "crystal nucleus," with ice crystals growing outwards until they occupy the entire water volume. The fact that ice is less dense than water, expands in volume, and has a unique aesthetic morphology all stem from this microscopic molecular rearrangement. Understanding freezing is a vivid lesson in understanding changes in the state of matter and energy transfer. Our "Observing Water Freezing" exhibit uses a sophisticated temperature control and microscopic imaging system to transform this usually slow and difficult-to-observe process
