Reading No snowflake looks like the other one. At Caltech (California Institute of Technology), the physicist Kenneth Libbrecht investigates why this is so and what influences the formation of snow crystals.

For four years, Libbrecht and his colleagues have been preparing the icy crystals in cold chambers and examining their shape under the microscope. By the way, they have managed to influence the crystal forms according to their wishes. "If you really understand something, you can control it. We can now make snow crystals with pretty much the shapes we'd like, "explains Libbrecht.

To create an ice crystal, you need a crystallization nucleus? in nature, for example, these are tiny specks of dust in the clouds. The ice crystal then forms around such a speck of dust. In their investigations, the researchers varied the humidity and temperature in a cold chamber to study the shape growth of the crystals. In their experiments, they were able to confirm hypotheses that the infinite variety of shapes of snowflakes is based on the infinite variety of humidity and temperature values ​​on Earth. For example, even the slightest difference between these two parameters in Libbrechts cold chamber is sufficient for two directly adjacent crystals to make them look different.

The scientists found that snow crystals grow rapidly at -15 ° C and form six prongs; At -10 ° C, the tips of the spikes grow slower and form hexagonal plates. At? 5 ° C the top and bottom grow fast, the sides grow slowly and small columns form. The many different crystals produced in the cold chamber were photographed, measured and analyzed by Libbrecht. He summarized the results in a table from which one can read out what a snow crystal looks like that grows at a certain humidity and temperature.

"I advise my friends to take a magnifying glass when they drive to cold places so they can look at the different crystals when it's snowing, " says Librecht. "From experience I can tell you that you would be thrilled. You can make such beautiful and amazing observations.? display

Arndt Dürr


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