Tim Garrett/University of Utah

ScienceShot: The True Shape of Snowflakes

The classic image of a snowflake is a fluke. That flat, six-sided crystal with delicate filigree patterns of sharp branches occurs in only about one in every 1000 flakes. And a snowflake seen in 3D is another beast entirely. Researchers have developed a camera system that shoots untouched flakes "in the wild" as they fall from the sky. By grabbing a series of images of the tumbling crystals—its exposure time is one-40,000th of a second, compared with about one-200th in normal photography—the camera is revealing the true shape diversity of snowflakes. For example, long before they reach the ground, many flakes are attacked by millions of freezing water droplets and end up as rough little ice pellets known as graupel. Flakes that avoid that process often end up sticking to other flakes, forming big, fluffy aggregates in midflight. And even those flakes that trace a lonely path through the air are usually not flat but bushy. (Some of this variety is showcased in the picture above.) Besides providing beautiful real-time 3D snowflake photographs from a ski resort in Utah, the goal is to improve weather modeling. More accurate data on how fast snowflakes fall and how their shapes interacts with radar will improve predictions of when and where storms will dump snow and how much.

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