The mysterious snowflake

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When the snow comes to the northland, there is always a fascination about the falling flakes. As the first ones descend upon the earth, we are enchanted and drawn to the outdoors. Perhaps this feeling is instilled in us from a time that, when the ground was covered with snow, the struggle by animals for existence was accentuated.

These days, however, we are only slightly inconvenienced by a snowfall, having to deal with it only as long as it takes for the power snow blowers, shovels, and plow and salt trucks to clear our walks and byways. But, many other non-hibernating, lower animals are living on a razor’s edge that divides the line between survival and death. The depth and nature of a snowfall can easily nudge them to one side or the other.

Aristotle, the father of natural history, was the first to make written notes on his idea of how snowflakes were formed, and since that time men have used photography, microscopes, and numerous electronic devices to make countless studies of snowflakes. One of the most intensive studies was made by a man by the name of Wilson Bentley of Jericho, Vt., who made more than 4,800 photomicrographs of snowflakes and confirmed what Aristotle had concluded: no two were exactly alike.

The next time a snowfall occurs, use a magnifying glass to examine the flakes that fall on your sleeve or a piece of polished glass. Be careful, however, and do not breathe on them as they will quickly disappear. Each flake will be found to be an exquisite product of nature’s artistic ability expressed in complex, symmetrical, geometrical patterns.

The formation of a snowflake begins up in a cloud where a minute dust particle provides a base on which water molecules can condense to form a snow crystal. When the crystal is quite small, a physical phenomenon called faceting controls its growth, and it quickly develops into a hexagonal prism. As the crystal grows, the edges of its six sides stick out, and this causes the hexagon to sprout arms. The arms are modified by air bubbles trapped randomly within, and these and other factors result in the infinite number of shapes a snowflake may assume. Scientists also tell us the basic hexagonal shape is directly related to the fact that a molecule of water is composed of two atoms of hydrogen and one of oxygen and is crystallized directly from the vapor state. If the molecule of water had passed from vapor to liquid to solid, we would not have snowflakes but non-descript lumps of sleet and hail.

If the flakes are tiny and with either six-sided columns or plates, you will know that they were formed in very high, cold clouds. If they are larger (some may measure up to a half inch in diameter) and are in the shape of a six-pointed star or a solid hexagon with six identical inlaid designs, they came from low, relatively warm clouds. Sometimes these larger flakes consist of several fused crystals that combine a star with a solid hexagon.

After snow has been on the ground for a time and the temperature has fluctuated between below and above freezing, the original form of the flakes undergoes a change. At first, particles with an angular outline are produced, but as the temperature goes up and down, they become rounded to form a variety of exotic shapes. These flakes make up so-called corn snow that is welcomed by skiers.

Physics, chemistry, and geometry are involved in the formation of snowflakes, and I am not so sure all of the details of this wonder of nature are completely understood. In any event, I am sure the 19th century naturalist, philosopher, and social reformer Henry David Thoreau did not concern himself with scientific details when he wrote the following in his journal on 5 January 1856: “How full of the creative genius is the air in which these are generated! I should hardly admire more if real stars fell and lodged on my coat. Nature is full of genius, full of the divinity; so that not a snowflake escapes its fashioning hand.”

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

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