Every special little snowflake may be unique, but they’re not all that different from each other, at least at the molecular level.  Depending on the temperature and humidity at which they form, snow crystals form into different shapes. Scientists have categorized the crystal structures of snowflakes into 39 different categories, including columns, irregular particles, and more, all of which are visualized in the graphic above by chemistry teacher and science infographic wiz Andry Brunning of Compound Interest.

As scientists find out more about crystal structures, the types of known snowflakes out there have increased. There were only 21 categories of crystal shapes in the 1930s, but in recent years, that number has ballooned up to 121 subtypes—you’ll have to look at the expanded version of the graphic to see those (along the bottom of the image). But those are pretty fine-grained definitions. There are 39 intermediate classifications of basic snowflake shapes, including several irregularly shaped forms of solid precipitation. 

You may not be able to tell a column crystal from a rimed crystal with the naked eye, but you can definitely throw out a few of these categorizations to impress people while you’re snowed in this weekend.

[h/t: Smithsonian]