Let It… Snow?

With the weather outside the way it is, one would think it was Christmas vacation this week, rather than Thanksgiving. It is beautiful out there, though, and it was a pleasure to walk in it this morning. Snow is definitely preferable at 28 degrees to rain at 36 degrees.

All this snow, however, reminded me of a little childhood wisdom — no two snowflakes are identical. Being now older, wiser, and a little more well-versed in the world of statistics, it has occurred to me to wonder a time or three over the past couple of years just how this can be. Mind you, I wouldn’t put it past an omnipotent God to actually cause every drop of moisture to crystallize into a historically and relationally unique shape once it drops below that all-important threshold of 32 degrees Farenheit (or 0 degrees Centigrade, for those of you using a different system). But by the same token, it occurred to me to wonder just how much proof was really out there on the topic.

So, I ran a “Google”:http://www.google.com “search”:http://www.google.com/search?hl=en&q=snow+no+two+flakes+identical and “this”:http://www.straightdope.com/classics/a3_392.html is what I came up with:

**How do they know with any degree of certainty that no two snowflakes are alike? When I took statistics I was taught that to draw a valid conclusion one had to take a representative sample of the entire population. But considering the impossibly large number of flakes in a single snowfall, let alone that have ever fallen, how could snowologists have possibly taken a sample large enough to conclude that no two are alike? –Leslie B. Turner, San Pedro, California**

They didn’t, of course. Chances are, in fact, that there are lots of duplicates. What the snowologists really mean is that your chance of finding duplicates is virtually zero. It’s been calculated that in a volume of snow two feet square by ten inches deep there are roughly one million flakes. Multiply that by the millions of square miles that are covered by snow each year (nearly one fourth of the earth’s land surface), and then multiply that by the billions of winters that have occurred since the dawn of time, and it’s obvious we’re talking unimaginable googols of flakes. Some of these are surely repeats.

On the other hand, a single snow crystal contains perhaps 100 million molecules, which can be arranged in a gigajillion different ways. By contrast, the number of flakes that have ever been photographed in the history of snow research amounts to a few tens of thousands. So it seems pretty safe to say nobody’s ever going to get documentary evidence of duplication. Still, it could happen, and what’s more, Leslie, it could happen to you. The way I figure, anybody who could dream up a question like this has got to have a lot of time on his hands. Get out and start looking.

There are a whole lot of other mathematical discussions on that page, but unless you’re something of a math geek like me, you’ll probably just find it mind-numbingly boring.

5 thoughts on “Let It… Snow?”

  1. Snow, eh? It’s 81 & sunny here today. That’s not really ideal Thanksgiving weather either, is it? We had to turn on the a/c for a bit. That’s Texas for ya!

  2. While I have never personally analyzed snowflakes to the extent that I can tell what their patterns are like, I think it is just one more example of how intricate and amazing God is. He rocks! When I think of no two things being exactly alike, I think of fingerprints. (I have been watching a bunch of crime solving shows lately.) Think of all the billions of people in the world. No two have the same exact fingerprints! That is constantly blowing me away. Fingerprints may sound insignificant to some, but finding a print or two at a crime scene makes all the difference between solving a crime and not solving one.

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