“Snowflakes,” by Chris Dombrowski

The formation of snowflakes—essentially, the idiosyncratic way that water crystallizes when suspended in our atmosphere—is an extremely complex process that still hasn’t been fully described by scientific formulas. “People think that a snowflake is just a frozen raindrop,” says Caltech physics professor Kenneth Libbrecht, who’s spent the past few decades studying the process of snowflake formation. “But that’s sleet, just little ice cubes, and not even close to what a snowflake is.”

Over the course of his research, Libbrecht’s work has grown to encompass art and science. He’s produced both scientific papers and hundreds of beautiful photos of natural snowflakes (which he’s published in several different books and had featured on U.S. postage stamps), and also devised ingenious ways to artificially grow snowflakes in a lab to study their formation in microscopic detail.