Many factors determine snowflake size, shape

The world’s largest snowflakes hit the ground during a January storm in 1887 at Fort Keogh, on the western edge of Miles City. At least that’s what’s listed in the Guinness World Records. A rancher described the snowflakes as “larger than milk pans” and measured one at 15 inches wide. A mailman, stuck in the blizzard, also witnessed the huge flakes, although their claim lacked tangible, corroborating evidence. Other challengers don’t even come close to dethroning the Miles City behemoth. Weather officials in Berlin, Germany, reported a storm in 1915 that produced 4-inch-wide flakes shaped like oval bowls, and a fall snowstorm in Laramie, Wyo., in September of 1970 dropped 3-inch-wide flakes. "While it’s tempting to blow off the record-breaking flakes as a tall tale, Kenneth G. Libbrecht, a physicist with a passion for snowflakes, believes in at least the possibility of pan-sized snowflakes. “It’s not an individual snow crystal — it’s gobs of snow crystals stuck to together,” said Libbrecht, who heads the physics department at the California Institute of Technology in Pasadena, Calif. It’s hard to believe in softball-sized hailstones, but people pull them out of their freezers, he said. Libbrecht created the Web site SnowCrystals.com, which includes online photo galleries of snowflakes along with the science...read more