Roundtable tonight was postponed due to snow. Scouts afraid of the snow? I thought a Scout was Brave. (The Scout Law says nothing about a Scout being Smart. Perhaps we need a 13th point? Or maybe only I do. But it does say that a Scout is Obedient – and I was told to stay home tonight, so that is good enough for me!)

Got me to thinking about SNOW! My wife is tired of it. My kids love playing in it. And my dog pretty much disappears in it. My mind began to wander!

I picked up a copy of Don Voorhees’ The Book of Totally Useless Information and I’m going to blatantly repost a section here without permission, but with attribution:

Why aren’t any two snowflakes alike?

How could it be that no two snowflakes are identical? It seems pretty improbable when you consider that a rough estimate of the numbers of snowflakes that have fallen on the Earth throughout its history is about 1,000,000,000,000,000,000,000,000,000,000,000,000. That’s a lot of snowmen!

There are about eight to one hundred different recognized classes of snowflakes. Most are variations on the basic hexagonal shape that water molecules assume when frozen. When water molecules freeze, they form an ordered arrangement based on the sixty-degree angles assumed by the oxygen atoms relative to the hydrogen atoms. If you enlarged a frozen water molecule about a billion times it would resemble the head of Mickey Mouse, the “head” being the oxygen atom, the “ears” being the two hydrogen atoms.

Shapes within the basic hexagonal arrangement can vary greatly. Snowflakes can be thick or thin starlike plates, with different branching patterns (dendrites); columnar, needlelike, or irregular.

[This isn’t in the book, but I found it really interesting when looking for an illustration to go with this story. Check out snowcrystals.com, which is really hosted by a class at CalTech. Great stuff!]

A snowflake needs a nucleus around which to form. This is usually a spec of dust, sea salt, or some other particle in a snow cloud. Water vapor molecules accumulate and freeze on the airborne particles. As they start to grow into ice crystals, they are blown around and begin to fall toward Earth, all the while gathering more water droplets and growing into larger ice crystals. What makes snowflakes unique form one another is the slightly different conditions of temperature and moisture under which each flake is born and develops. No two specks of dust are truly identical and the microclimate each flake passes through in the cloud is slightly different from that for others.

For example, the temperature and moisture content of snow clouds vary from one point in space to another, and no snowflake is born in exactly the same space or travels exactly the same path in its development. These might seem like minor differences, but they are enough to make all snowflakes different.

Snowflakes that are created at 32° to 27° F are hexagonal plates, at 27° to 23° needle shapes form, at 23° to 18° hollow prismatic columns form, at 18° to 10° hexagonal plates again form, at 10° to 3° fernlike stars (dendrites) form, at -3° to -13° plates form, and at -13° to -53° hollow prismatic columns form. Snowflakes only form at these relatively mild temperatures. The polar regions are too cold and rarely receive snowflakes. Usually all they get is snow dust.

From time to time, similar snowflakes are found. They look to the eye to be the same, but upon closer examination, there will be slight differences. After all, snowflakes have about a billion billion molecules. If two were ever identical, now that would be truly amazing!

Voorhees, Don. “Why aren’t any two snowflakes alike?.” The Book of Totally Useless Information. New York : Mjf Books, 1993. 24-25. Print.