Chasing Snowflakes
by Ken Libbrecht for CBC
Snowflakes hide scientific mysteries in their delicate, crystalline beauty. And there's no one better to explain them than Caltech physicist Ken Libbrecht. He's one of the world's foremost experts on snowflakes, or as he likes to call them, snow crystals. So here's Ken Libbrecht answering five snowflake mysteries.
You start out with a little round piece of ice. As the water molecules bind together, it's growing. They're not a hexagon yet, so there are some rough areas. Additional water molecules are drawn to the molecular energy of these rough patches, filling in the structure. Until we are left with a six-sided crystal, with those nice crisp, straight facets. This process is how the geometry of the water molecule, is transferred to the geometry of a large crystal, through this process of faceting. And when we grow little tiny crystals in the lab we get these little hexagonal prisms. And this also tells you why there's no four-sided snowflakes or five- or seven-, or eight-. You may cut those out of paper, but in practice, in nature, there is only six-sided snowflakes and it's because this is the way it works with ice.
Ken Libbrecht has a wealth of resource material at his site SnowCrystals.com.