Why Are Snowflakes Individually Unique?

Edge Effects editorial board member Eric Nost asked “Why are snowflakes individually unique?” to the team at the UW-Madison Morgridge Institute for Research’s Blue Sky Science program, who recruited Dr. Pao Wang to answer. The reply was originally posted at Blue Sky Science’s blog here and in the Wisconsin State Journal.

Two important factors influence the shape of a snowflake. One is the ambient temperature, and the other is humidity. A snowflake needs to grow under the condition of a super saturated environment.

The more moisture in the air, the more complicated and intricate the structure of the snowflake will be. So these two factors, the temperature and the super saturation are the most important factors that influence the shapes.

The folklore says that there aren’t two snowflakes that look exactly alike. I think that’s just a fancy way of saying that there are thousands of these different shapes, and people are always amazed that the shapes can be so complicated and different.

In reality, if you’re looking just with the naked eye you could see two snowflakes that look almost exactly alike. For example, some snowflakes consist of very simple hexagonal plates with very little design on the surface.

If you were to look into the structure of a snowflake using a microscope, you may see somewhat different structures, but they could be minimal.

With so many different shapes that snowflakes can take, the chances of seeing two similar snowflakes in your lifetime are small, although not zero. Most likely you’re going to see many different shapes, and it can be exciting to see so many configurations.

Featured image: Snowflake captured by a microscope. Michael. Wikimedia Commons. CC-BY-SA 2.0.

Pao Wang is a professor in the department of atmospheric and oceanic sciences at UW-Madison. Website.

Blue Sky Science is a collaboration of the Wisconsin State Journal and the UW-Madison Morgridge Institute for Research. The Blue Sky Science team finds experts to answer questions posed by visitors to Science Saturdays, a monthly series that features interactive exploration stations centered around a particular topic. Website.


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