A revolution for the science of snowflakes


The way snowflakes form is poorly understood. It seems clear that the process involves a subtle interplay of nonlinear effects in which small variations at the molecular level can produce large changes in the eventual shape. In particular, small levels of gaseous impurities are thought to have a major impact on the way these effects play out.

We all know the result: the amazing, beautiful and unique crystals that fall as snowflakes.

Watching and measuring the way snowflakes form is difficult for obvious reasons,a problem that has severely hampered our understanding of snow flake formation. But that looks set to change.

Kenneth Libbrecht and buddies at the California Institute of Technology in Pasadena have a built a machine that makes snowflakes in conditions that mimic those in the atmosphere. The crystals grow as they fall within this chamber and their size and thickness are measured when they land.

The work is the first systematic study of snowflake size and shape as a function of temperature and water vapor supersaturation. The results are workmanlike, merely confirming expectations. But they provide a baseline against which to measure other factors that influence snowflake formation, such as the levels of gaseous impurities. And when that happens we’ll be able to tease apart exactly what is going on when these crystals form for the first time.

Ref: arxiv.org/abs/0811.2994: Measurements of Snow Crystal Growth Dynamics in a Free-fall Convection Chamber

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