Snowflakes Can Be Larger Than a Frisbee

The colossal snowflake observed in 1887 was not a single, perfectly formed crystal like the ones often depicted, but rather an aggregate of many smaller snow crystals that clumped together. This massive formation, reportedly measuring 38 centimeters wide and 20 centimeters thick, was spotted by a rancher named Matt Coleman at Fort Keogh, Montana, during a fierce winter storm on January 28, 1887. While there is no photographic evidence of this specific event, the atmospheric conditions for creating such giant snowflakes are well understood by scientists.

The formation of such large snowflakes requires a specific set of weather conditions. Temperatures need to be at or slightly above freezing, which allows the surfaces of the falling snow crystals to be slightly wet. This moisture acts as an adhesive, causing the crystals to stick together as they collide during their descent. Additionally, calm or low-wind conditions are necessary to prevent these fragile aggregates from breaking apart as they fall.

While the 1887 Montana snowflake holds the record, other instances of unusually large snowflakes have been documented. In 1915, meteorologists in Berlin (Review) recorded flakes up to ten centimeters wide. Individual snow crystals, the single, intricate structures, are much smaller. The largest measured single snow crystal was a mere 10 millimeters from tip to tip. The truly giant "snowflakes" are a testament to the remarkable way these delicate ice structures can combine and grow under just the right circumstances, creating a spectacular and rare weather phenomenon.