The Natural Enquirer: Six-sided symmetry
How well I remember an afternoon walk last year when we were treated to an unusual winter sight-sundogs that flanked the sun, low in the western sky. The dictionary describes a sundog as a small rainbow or halo near the horizon just off the parhelic circle that, in turn, is defined as a luminous halo visible at the height of the sun and parallel to the horizon, caused by the sun’s rays reflecting off atmospheric ice crystals. (We’re going to learn some new words today.)
The Encyclopedia Britannica says that snow is “the solid form of water which grows while floating, rising or falling in the free air of the atmosphere.” The word “crystal” comes from the Greek word kryllos, meaning frost. Snow crystals dainty and brittle are generally hexagonal (six-sided) in pattern and are grouped by snow experts into plates, stellars (my favorites), columns, needles, spatial dendrites, capped columns or irregular crystals. They come in a wide range of shapes, from simple triangles and hexagons to lacy fern-like dendrites.
Snow crystals grow fast whenever there is a rich supply of moisture in the air. It is common for a snowflake to have 50 or more crystals interlocked with each other. Even the wispy cirrus clouds five to eight miles high, seen during the summer in the middle to low latitudes, are composed of ice crystals. Remember that much of the moderate to heavy rains in our area began as snow.
Day after day of scraping ice and frost off car windows becomes somewhat of a stale chore until that magical morning when, concealed beneath the thin layer of snow, just waiting to be appreciated, were hundreds of dainty ice flowers and other delicate frost creations formed in their matchless tracery on the inner surface of the glass.
One should be reminded more often to look at the brighter side of life. There is really much value in snow. Many plants and animals are dependent upon it for an insulating winter blanket, it being an emulsion of water and ice crystals. As it melts, it feeds the groundwater table. The snow high in the western mountains melts slowly well into the summer, supplying cities and farms at lower elevations with precious water.
I wonder how few people, while enjoying one or another of the winter sports, give even a passing thought to a single snowflake, multiplied by many trillions, upon which outdoor enthusiasts cross-country ski, skate or zip down a hill on sled or toboggan.
Catch a Falling Snowflake. Snowflakes form in clouds where the temperature is at freezing (32 degrees F) or below. The clouds are made up of water droplets so tiny that thousands of them could fit onto the dot in the letter “i.” Clouds also carry tiny particles of dust and salt that the wind has carried miles up into the sky from the surface of the earth and sea. When cooled, these particles of dust and salt attract the water molecules.
As the water molecules gather on a particle, they freeze and build ice crystals. This is the start of a snowflake or snow crystal. All snowflakes are six-sided crystals of ice, forming in one of seven basic shapes, depending on the temperature and humidity of the air.
Snowflakes melt quickly, so to catch them you need to plan ahead. Here are two ways for you to catch a snowflake and see what it looks like up close:
• Chill a sheet of dark construction paper outdoors or in the freezer, then go outside when it’s snowing and hold the paper out. Examine single flakes with a magnifying glass as they land on the paper, before they melt!
• You can make a permanent record of a snowflake using a pane of glass and some hair spray or artist’s fixative. Chill the spray and the glass in the freezer until you are ready to collect snowflakes. Spray the glass just before you go outside, then allow some flakes to settle on the glass. When you think you have enough, take the glass indoors and let it dry at room temperature for about 15 minutes. You will have a permanent record of some of nature’s most amazing designs.
A glacier is the macrocosmic form of snow. In its microscopic forms, snow epitomizes ethereal beauty. It is a clichè to say that no two snowflakes are identical, but it is a fact that each single small flake that has fallen throughout all of time, and that will fall through what remains of time, has been, and will be, a unique creation in symmetry and form.
Somewhere, on this day, the snow is falling. It may be sifting thinly on the cold sands of a desert, spreading a strange placidity and flecking the dark, upturned faces of a band of Semitic nomads. For them it is in the nature of a miracle, and it is certainly an omen and they are filled with awe and chilled with apprehension.
It may be whirling fiercely over the naked sweep of frozen plain in the Siberian steppe, or on the Canadian prairies, obliterating summer landmarks, climbing in scimitar drifts to wall up doors and windows of farmhouses. Inside, the people wait in patience. While the blizzard blows, they rest; when it is over, work will begin again. And in the spring the melted snows will water the new growth springing out of the black earth.
We can look forward, in more ways than one, to banks of snow stars, nature’s most beautiful example of six-sided symmetry.
Letter received by the Chicago Weather Bureau:
“Dear Sir, I thought you’d like to know that I have just shoveled nine inches of Partly Cloudy off my driveway.”
Peter Dring is a retired nature biologist and phenologist who lives in the Land O’ Lakes area. To comment on this story, visit the “Outdoors” section of StarJournalNOW.com.