Uniqueness of each individual snowflake born of water and temperature
Story & Photos By Alan Daugherty
It has long been understood that no two snowflakes are alike. This fact holds true of people. Snowflakes have characteristics dividing them into groups, like human races. Human birth-to-death is said to go from “dust to dust.” A single snowflake’s life span might be explained as “water to water.”
Two components, water and temperature, combine to create each snowflake. The multitude of variations for both factors determine the appearance of each unique flake. Flake growth originates from the atmosphere’s humidity. A snowflake emerges in growth stages, beginning with a water droplet attaching to a dust or pollen speck. Atmospheric temperature dictates the type of a snowflake’s growth. Greater humidity inspires additional snowflake growth.
The most recognized type of snowflake carries the name dendrite. Dendrites display six-fold radial symmetry, six identical arm designs attached at the center. It begins growth as a central hexagon plate, which supports six symmetrical branches of crystals often resembling ferns or trees. Eventually, the flake grows to a size it can no longer suspend in the atmosphere and begins falling to earth to create the winter wonderland enjoyed by many. Perhaps a flake will be joined with countless others in a child’s playful building of a snowman.
Snowflakes tend to flutter about during their freefall. Some collide. This often causes them to attach to one another forming a group of snowflakes prior to reaching the ground. The “aggregate” formed becomes what appears to humans as extremely large snowflakes.
Reaching the ground depends on a journey not passing through a warm mass of air causing the aggregate to melt.
Snowflakes form into four basic shapes. Dendrites comprise what most winter lovers recognize as a snowflake. It’s the only form used in advertising. Plates, needles and columns also form dependent on the cold and humidity.
Plates can be as simple as a solid crystal hexagon disk so small it requires sophisticated equipment to capture its image. Some grow to contain a pattern which then might give it the appearance of a hexagonal storm sewer grate. A thin plate can begin to grow six crystal arms, which can, in a perfect form, appear to be six additional plates growing symmetrically around the central plate. Stellar plates differ from dendrites because they do not exhibit any fern-like pattern on the arms.
The plate’s near cousin, a column, again holds the hexagon shape but has a height greater than its diameter. If solid it might be called a prism. It might have a center void, thus creating this type’s alternatives of solid columns and hollow columns.
The last form, as difficult to capture in a photo as its cousins, plate and column, is called a needle. They form as singular or a cluster. A solitary needle might look like a tiny pipe made of ice. When growing together they form the appearance of a set of wind chimes made of delicate crystal. An aggregate of needles mimics the retro game of “Pick-Up Sticks.”
Aggregates can fall to the ground comprised of different forms of flake types. Each form in a different air mass layer but attach during the fall through one temperature, then another. Dendrite snowflakes with one or more needles attached can appear after landing as though it grew as a three-dimensional snowflake. A similar appearance results when two dendrites collide. A crystal branch might break off one and remain attached to a full dendrite making it appear to be three-dimensional. When falling, snowflakes sometimes simply bounce off one another and not form as an aggregate.
How large can an aggregate become? The 1887 Guinness record aggregate from Montana measured 15 inches. Even 1 inch becomes impressive when falling. Try catching large aggregates on the tip of your tongue.
Rime complicates snowflake styles. Frozen droplets or tiny little beads attach to cover a single flake until it resembles an old-fashioned grandmother broach covered with rhinestones. They can even appear as a crystal form of a caramel popcorn ball. The rime coating creates a highly refractive light situation and thus creates an added difficulty, one nearly impossible, to capture a sharply focused photo. A blob of rime snowflakes are named graupel.
Scientific photos depict capped columns. These are created when a column falls into an alternative air mass. Conditions allow columns to form plates on both ends. The result resembles a spool that once held sewing thread.
Great snowflakes grow in temperatures near zero. Look for needles at 20o F, and columns at plus or minus 20o. Sleet is not snowflakes. It’s frozen rain. Freezing moisture creates frost growing on objects, but frost differs with snow.
Snow forms crystal clear. All colors of visible spectrum light pass through clear snow crystals and thus appear to humans as white. Drifts can also reflect light tint colors of nearby objects. The smallest flakes, the diameter of hair, remain suspended and sparkle in sunlight giving them the name “Diamond Dust.”
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