What makes the snowflake shapes?
Pro Research Analysisby 
Searched over 200M research papers
Consensus Meter
The Science Behind Snowflake Shapes
Hexagonal Symmetry in Snowflakes
The iconic six-sided symmetry of snowflakes has fascinated scientists for centuries. Johannes Kepler, in his 1611 work "De nive sexangula," was among the first to ponder why snowflakes consistently exhibit hexagonal symmetry. Kepler proposed that the orderly stacking of frozen water particles, which he referred to as "globules," could explain this phenomenon. This idea laid the groundwork for the field of crystallography, which studies the geometric shapes of crystals based on the arrangement of their constituent particles.
Influence of Temperature and Humidity
The shape of a snowflake is highly sensitive to environmental conditions, particularly temperature and humidity. Slight changes in these factors can lead to a variety of snowflake morphologies, including hexagonal plates, needles, and dendritic structures. The sixfold dendritic shape, for example, is a result of a balance between dendritic growth and the anisotropy of crystal surface free energy. At around -16°C, the interface between the prismatic face of ice and water undergoes a roughening transition, which influences the formation of faceted plates and columns.
Crystal Growth and Molecular Interactions
The growth of snowflakes is a complex process that involves interactions at both molecular and macroscopic levels. Near the melting point, the surface of ice supports a thin liquid-like layer due to a premelting transition, which affects the growth morphology of ice crystals. Computer simulations have shown that below about -2°C, the coupling of interfaces in this quasi-liquid layer suppresses long-wavelength roughness, leading to smoother crystal surfaces and slower growth rates.
Structural Dynamics During Formation
The formation of snowflakes involves intricate structural dynamics. Early snowflakes, composed of a few crystals, exhibit specific patterns based on the arrangement and attachment of these crystals. For instance, snowflakes with two crystals of the same shape tend to have one crystal attached near the center of the other, while those with different shapes have a smaller crystal attached near the tip of the larger one. The arrangement of multiple crystals can also influence the falling motion and aggregation behavior of snowflakes.
Technological Advances in Snowflake Study
Modern technology has significantly advanced our understanding of snowflake shapes. Instruments like the Multi-Angle Snowflake Camera (MASC) and the Two-Dimensional Video Disdrometer (2DVD) provide high-resolution images and precise measurements of snowflake size and shape. These tools allow for detailed analysis of snowflake morphology and the factors influencing their formation. Additionally, 3D shape reconstruction techniques based on high-resolution photographs offer realistic models of snowflakes, enhancing our ability to study their complex structures.
Conclusion
The shapes of snowflakes are the result of a delicate interplay between environmental conditions, molecular interactions, and structural dynamics. From Kepler's early observations to modern technological advancements, our understanding of these intricate ice crystals continues to evolve, revealing the fascinating complexity behind their seemingly simple beauty.
Sources and full results
Most relevant research papers on this topic