Meet Kenneth Libbrecht:
Libbrecht’s process, developed over the past few years, is done in a cold chamber and takes about 45 minutes in total. He starts with a completely clean piece of glass, and scatters many microscopic ice crystals onto it. With a microscope, he isolates a particular crystal, then blows slightly warmer humid air onto the glass. The water vapor condenses on the seed crystal, just like in a real cloud, eventually forming a visible snowflake.
Working with this process, Libbrecht has determined the temperature and humidity levels that lead to each particular kind of snowflake. “I call them ‘designer snowflakes,’ because you can change the conditions as you grow them and predict what they’ll will look like,” he says. Among other things, he’s found that a snowflake with a thin edge grows faster, causing the edge to sharpen even further, ultimately leading to a relatively large flake. Snowflakes that begin with blunter edges, however, grow more slowly and remain blunt, leading to blocky prisms, rather than elegant plates.
(Time-lapse film via Libbrecht’s website, snowcrystals.com)