Researchers from the University of Chicago, renowned American chemists, used mathematical analysis to explain for the first time why water freezes at different temperatures. Their work provides a framework to predict and control the formation of snow and ice with greater precision. The study was published in the proceedings of the annual meeting of the American Chemical Society (ACS).
While it is commonly taught that water transitions from liquid to solid at 0 °C under normal pressure, real-world freezing temperatures are influenced by a range of impurities. In fact, pure distilled water must be cooled far below this point to freeze reliably, a phenomenon known as supercooling, which can reach around -40 °C in practice without nucleation centers.
In their theoretical model, the researchers describe how the microscopic details of surfaces and particles can shift the freezing point of water. The study considers a spectrum of surfaces that can be encountered in nature and industry, including soot particles, bacteria, and certain proteins, all of which can act as nucleation sites for ice crystals.
The team compiled more than a hundred existing measurements that relate the angles between microscopic protrusions on particle surfaces to the observed freezing points. By applying physical and statistical models, they examined how water interacts with surfaces, how strongly water molecules bind to these surfaces, and how the geometry of surface features influences ice nucleation.
As a result, chemists derived a mathematical expression that shows certain angular configurations among surface features can promote the aggregation and orderly crystallization of water molecules at comparatively higher temperatures. This insight helps explain why some surfaces encourage ice formation sooner than others under the same environmental conditions.
The authors suggest that their model could guide the design of materials with tailored surface properties that induce ice formation more efficiently while requiring less energy input. Such materials could find applications in ice or snow generation systems, and the approach could be used to seed clouds with particles that encourage snowfall under controlled conditions, potentially benefiting weather modification efforts or cold-chain technologies.
For readers curious about related questions, prior discussions in the field have addressed why snow yields a crunching sound underfoot, a phenomenon linked to the microstructure of snow and the metamorphism of ice crystals at the surface of packed snow.