6: number of arms found on the simplest and most common type of snow flakes.

28 to 5: Degrees Fahrenheit at which the common stellar plated snowflakes forms.

2-4: Measurement in millimeters of most stellar dendrite snowflakes, which can be seen with the naked eye.

12: Number of sides occurring in a rare kind of crystal twinning snowflake.

10: Number of forms the most common types of frozen precipitation takes.

1951: Year the International Commission on Snow and Ice produced a simple classification system for those 10 forms.

Source: www.its.caltech.edu