Snowflakes still hold mystery

This post contributed by Nadine Lymn, ESA Director of Public Affairs Their silent, shimmery beauty has long stirred human aesthetic appreciation and for centuries individuals have sought to unravel the secrets of snowflakes.  Why are there so many varieties?  Why do all snowflakes have six “arms”?  And why does each flake appear unique, no matter how many fall from the sky? We know the answers to these questions as described on the National Oceanic and Atmospheric Administration’s website: temperature and humidity determine their shape, their six “arms” are the result of the internal order of an ice crystal’s water molecules, and, because each crystal encounters slightly different atmospheric conditions, each snowflake appears unique. But enough mystery about the particulars remains that some scientists continue to try to unravel it.  One such scientist is Caltech physicist Kenneth Libbrecht, who is looking into the physics of exactly how water vapor molecules are incorporated into a growing ice crystal.  He has also created a webpage, SnowCrystals.com which is a true treasure-trove of information for anyone interested in snowflakes.  It includes not only magnificent photographs taken by Libbrecht, such as the one below, but also showcases the science of snowflakes and the historical figures who sought to understand these ephemeral beauties. For example, as long ago as 1611, German mathematician Johannes Kepler, put together a “treatise” for the king which he entitled, A New Year’s Gift or On the Six-Cornered Snowflake. Libbrecht notes that this was the first scientific reference to snow crystals and that Kepler was especially intrigued by the six arms of snowflakes, speculating that it must have something to do with the morphology of the crystals. The website includes other individuals, such as “Snowflake Man” Wilson Bentley, a self-educated Vermont farmer, who became so enraptured with snowflakes he saw under his microscope that he persuaded his parents to purchase a special bellows camera to try to capture them before they melted.  After years of trial and error, Bentley became the first person to take a photomicrograph of an ice crystal and went on to capture 5,000 images of snowflakes.  According to Duncan Blanchard, who wrote a biography about him, Bentley’s first article appeared in Popular Scientific Monthly in 1898 and included this vivid description of an ice crystal: “A careful study of this internal structure not only reveals new and far greater elegance of form than the simple outlines exhibit, but by means of these wonderfully delicate and exquisite figures much may be learned of the history of each crystal, and the changes through which it has passed in its journey through cloudland.  Was ever life history written in more...

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