Cold water vapor gloms onto these little specks, triggering an amazing chain reaction of molecular growth. As a result, snow crystals are born. One by one, other molecules of water vapor are magnetically pulled toward these tiny seed crystals. At some magic moment, the growing crystals give way to gravity and start free-falling to earth at 2 to 3 miles per hour. Exactly what drops from the sky to your fleece-covered head depends on atmospheric conditions, such as humidity, temperature, and wind.
Nothing adds that wonderful winter hush to the forest like a fresh dump of stellar crystals.
Their complex filigree structures trap sound waves in billions of tiny air pockets, making stellar crystals nature's perfect sound absorbers. They also trap heat better than any other crystal, providing the highest insulation value for cavelike emergency shelters dug into a snowbank. Since the slightest turbulence will destroy both stellar crystals and hexagonal plates, when you see either coming down, it's a good sign that winds are relatively calm above your head. Expect stable weather for at least the next few hours. As these crystals form in the upper atmosphere, they often create a wide, broken halo of orange and green light around the sun, better known as a sundog.