Stellar dendrites, sectored plates, hollow columns, needles, spatial dendrites, capped columns, rimed crystals…What do these terms have in common? They are snowflakes!
Have you ever watched a snowflake fall from the sky and wondered at its beautiful intricacy? Amazingly, you are simply looking at ice—tiny snow crystals that have been shaped and bonded together.
A snowflake’s initial shape is determined in the clouds, with temperature playing the largest role. But, its ultimate formation and size depend on a variety of additional factors, such as collisions with other crystals, different layers of air at different temperatures and varying moisture levels. One constant in the shape, however, is the fact that all snowflakes are six-sided. Frozen water molecules—ice—are comprised of two hydrogen atoms and one oxygen atom, and because of the way that hydrogen atoms bond, snow crystals always attach into hexagon-shaped snowflakes.
To see this for yourself, try the following winter experiment: Place a piece of black construction paper on a cookie sheet and leave it in your freezer until the next snowfall. Then, take it outside and catch the falling flakes. The frozen sheet will allow you to view them longer. Perhaps you can even identify some of the shapes yourself. If the temperature is 3°F (-16°C) to 10°F (-12°C), look for the standard six-branched stellar (meaning “star”) dendrites (meaning “tree-like”). Or, if the temperature is a little warmer, 14°F (-10°C) to 21°F (-6°C), look for the most common snowflake, hollow columns. These have the hexagonal shape of wooden pencils with hollow ends.
Finally, it has been said that no two snowflakes are alike. Well, for practical purposes, that is hard to prove absolutely. Why? Because it is estimated that one undecillion snowflakes (that is a 1 followed by 36 zeroes) have fallen to earth. How do you try to compare all of them—especially when most have already melted? Impossible!
Nevertheless, scientists generally believe that the unique journey that each snowflake takes prevents two from ever being alike. Now you can have fun this winter trying to prove them right or wrong!
Sources: SnowCrystals.com, csmonitor.com, USATODAY.com