Snowflakes don’t usually form into the beautiful, perfectly symmetrical, lace-like patterns we see on holiday cards every year. They fall at different speeds and frequently lump together. Snowflakes form when water molecules in a cloud transform from water vapor gas to solid ice, forming an ice crystal. These ice crystals swirl around in the clouds and fall from the sky. When water droplets freeze upon contact with an ice crystal, snow crystals are formed, and when these snow crystals clump together, snowflakes are created.
So, how big can snowflakes get? The largest snowflake on record was 15 inches (38 cm) wide, and it was spotted by a Montana rancher in 1887.
Guinness World Records lists the largest snowflake as having fallen during a storm in January 1887 at Fort Keogh, in Montana. The rancher who witnessed the huge snowflakes described them as being “larger than milk pans,” and he measured one at a whopping 15 inches. There's plenty of reason to be skeptical about this anecdote – especially as there's no corroborating evidence to support the claim – but researchers say it’s not impossible.
In order for snowflakes over a foot wide to occur, however, certain conditions need to be met. There must be little to no wind, to prevent them from breaking apart. There must also be a very high level of moisture in the air for the snowflake to gather an abundance of frozen water droplets and ice crystals on its way to the ground.
Let it snow:
- A snowflake’s shape is the result of what occurs in the clouds where it forms. Its appearance and size are affected by various moisture and temperature conditions.
- Sandra Yuter, a faculty fellow at the Center for Geospatial Analytics at NC State, has collected images of over two million snowflakes. The majority of snowflakes, she maintains, are made up of a jumble of small snowflakes rather than one giant crystal.
- You never know when you might come across a giant snowflake. Amateur weather observer Herbert H. Close Jr. witnessed giant snowflakes falling around him one night last winter. “It’s a matter of being at the right place at the right time,” he said. “Sometimes you get lucky.”