If you've ever wondered what snowflakes truly look like, spend a few moments with these images from the Electron Microscopy Unit of the Beltsville Agricultural Research Center in Beltsville, Maryland. At the EMU, where other areas of focus include crop pathogens and livestock diseases, "studying the structure of snow is vital to several areas of science as well as to activities that affect our daily lives." That's no doubt true. But for the rest of us, snow's structure is just beautiful. Enjoy!

The most complex snow-crystal classification system was devised in 1966 by Japanese meteorologists C. Magono and C.W. Lee. Entitled "Meteorological Classification of Natural Snow Crystals" (pdf), it describes more than 80 types of crystal. Above is P2b, or "stellar crystal with sectorlike ends."

The difference between what's seen under a light microscope — or would be seen by our eyes, were they a hundred times more powerful — and an electron microscope is shown in these two views of hoar crystals from a Wyoming snow pit.

For a near-instant, all-natural 3-D snowflake, cross your eyes and relax your vision until you can see three images. Then focus on the central image. Voila!

One more 3-D snowflake. If you dig this, there are six more available from the Electron Microscopy Unit.

Snow crystals often fall through supercooled cloud droplets, which can stay unfrozen down to -40 degrees Fahrenheit. The droplets coat snow crystals with still more crystals, and that frost is called rime.

Snowflake structure is visible at many levels, from a relatively coarse 100x magnification (top left) down to 1,800x (bottom right).

Falling snowflakes were collected at different temperatures on Bearden Mountain, West Virginia. At top left, 14 degrees Fahrenheit; top right, -4 degrees Fahrenheit; below, -22 degrees Fahrenheit.