Wherever you find yourself this Christmas (or your politically friendly holiday of choice), everything will be much more festive if you at least imagine that it's snowing out. Go on, imagine it! Now, we're guessing that all of those flakes of snow that you're imagining are hexagons, because that's what snow does, due to the arrangement of hydrogen bonds in frozen water molecules. Occasionally, though, snowflakes show up in the form of triangles, like the fine specimens in the picture above. For quite a while, nobody could figure out how his happened, until intrepid scientists managed to recreate it in a lab in 2009. The secret turned out to be little tiny impurities like dust particles, which, if a snowflake runs into one while it's forming, can imbalance it, leading to an aerodynamic change that streamlines it into a triangle shape instead of a hexagon.
Triangular snowflakes are much rarer than hexagonal ones, but you can find them if you look hard enough. We'd encourage you to give it a try if you have the option. Or, you know, you can go do something a little more exciting, like tearing open presents or stuffing your face with food.
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