In 1986, researchers at the Schlumberger-Doll Research Lab study how ice crystals form into snowflakes, and why each snowflake has its own uniform symmetric pattern, yet is different from all other snowflakes.
How Snowflakes Form (And Yes, Each One Is Different)
JANE PAULEY, anchor:
Well, the weather report calls for snow in some parts of the country today, which you’ve kind of gotta expect, this being February. Our science correspondent Robert Bazell is here with us this morning to talk of what aspect of the snow? The snowflake.
ROBERT BAZELL, reporting:
Good morning, Jane. Pleasant change from the weather in Rio, right?
PAULEY: It is.
BAZELL: Well, I have a confession to make. I grew up in California and I never saw snow fall until I was an adult so I’m so fascinated by it. When I heard scientists were studying snowflakes, I couldn’t resist doing a story on it.
The discomfort and inconvenience of a snowstorm are well-known to those of us outside the sun belt, but in the sun belt, you miss the magic of the snow. This is Central Park in Manhattan on a recent afternoon. The beauty is not just in the vistas. It is also in the close-up look at the snowflake, their intricate geometrical patterns, each one different. Hebert Levine and his colleague at the Schlumberger-Doll research labs in Ridgefield, Connecticut have been so intrigued by snowflakes, they’ve been studying them in detail. Study snowflakes?
HERBERT LEVINE: Scientists always really want to understand why nature does what it does, why things look the way they look and it’s more a sense of wonder and understanding how simples processes can actually give rise to such fascinating things that drives a lot of the work on such things as snowflakes. The reason you should be interested in snowflakes is that snowflakes are inherently interesting.
BAZELL: Here, Jing-Den Chen injects a liquid between two plates. This experiment duplicates some of the conditions in the atmosphere when a crystal of ice from a cloud becomes a snowflake. By using different patterns, various liquids, and changing other conditions, the scientists can create different snowflake-like patterns. One of the things they have learned is why snowflakes are so different from one another while the pattern in one flake is so uniform.
LEVINE: What actually occurs in the growth of snowflakes is a very orderly process. The reason all snowflakes are different is actually because a snowflake starts out in the cloud. There’s a little ice crystal and it falls through the atmosphere and the atmosphere, the temperature, water vapor pressure is always changing so it sort of exhibits a varying environment and that leaves an imprint on the snowflake, but each arm of the snowflake, of course, sees the same environment as it’s falling so therefore, since the process is simple and not chaotic, it really gets the same pattern imprinted on it.
BAZELL: The researchers also grow metallic crystals. This is zinc sulfate. This project began for esoteric reasons. It turns out to have practical applications.
LEVINE: If one is trying to design things, such as aircraft wings and grow pieces of metal from castings, what one really wants to know is how strong the metal will be and metallurgists have known for a long time what determines the strength of final casting, the final shape that you grow out of let’s say liquid metal is the actual microstructure, the actual underlying patterns whereby the things grew and how they actually came together to form the final melt so by knowing for example the size of these branches and the relative spacing between different branches, a metallurgist might be able to predict how strong the final metal is.
BAZELL: Practical applications or not – Snowflakes remain one of the best creations of winter.
1. Create a chart with the days of the week. Create weather symbols (sun, rain, cloud, snow, etc.) and each day have students place the appropriate symbol on the chart.
2. Collect snow (solid) in a dish, observe it, and then bring it inside and watch as it melts (liquid) due to the temperature change from outdoors to indoors. Leave the melted snow in the classroom near a window and observe the changes occurring. Soon all the liquid will disappear (gas) as it evaporates.
One of the best things about winter is playing in the snow. But as the weather gets colder, you may wonder why you often see icy rain — or just plain ice — instead of snow.
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