# The structure of a snowflake

Russian photographer Andrew Osokin is a master of snowflake macro photography. He captured a dendrite snowflake cluster seconds after it landed. Dendrite crystals occupy a lot space and are optimal for high accumulations of snow. (Andrew Osokin)

Heavy snow is in the forecast.

Have you ever taken the time to analyze the structure of a snowflake after it lands? I remember as a kid I would study snowflakes after they landed on my sled as I was waiting to make the next sledding run with my friends.

I observed snowflakes in the shape of plates, needles, dendrites, graupel, and often indistinguishable blobs of ice crystals. Heavy snow, my favorite, often fell in big blobs of dendrite crystals.

See below for more photos.

What determines the shape of the snowflake crystal? The temperature in the cloud where the crystal forms influences the crystal structure. Cold temperatures in the clouds, 10 degrees or less, produce sharper tips and “snowflake arms” that are common with the dendrite snowflakes. Warmer temperatures in the clouds, 25 to 30 degrees, produce smoother, less intricate crystals.

Here’s a breakdown of snowflake shapes by temperature at formation:

* 32-25° F - Thin hexagonal plates

* 25-21° F - Needles

* 21-14° F - Hollow columns

* 14-10° F - Sector plates (hexagons with indentations)

* 10-3° F - Dendrites (lacy hexagonal shapes)

(Source: Anne Marie Helmenstine, About.com)

Another factor in the snowflake shape is the temperature of the air column in which the snowflake falls. If the snowflake crystal falls through air slightly above freezing, it can partially melt. If the snowflake then enters air below freezing again it can refreeze into grauple. If the air column stays above freezing all the way to the surface, however, wet snow or rain will result.

Here’s a great video explainer from the American Chemical Society (Bytesize Science) on the science of snowflakes:

A snowflake close-up. (Andrew Osokin)

Andrew Osokin has focused his photography on individual snowflakes that fell upon the ground and were in the process of melting. In this post, I am sharing a few examples of Andrew’s snowflake photography.

Andrew’s work stands out for both the clarity of his photographs and his ability to isolate a single snowflake. In a snowstorm, isolating a single snowflake is not always easy. Andrew used a Nikon D80 or Nikon D90 DSLR with a 60mm or 90mm macro lens for these photos.

A snowflake close-up. (Andrew Osokin)

A snowflake close-up. (Andrew Osokin)

A snowflake close-up. (Andrew Osokin)

Are you hoping for lots of dendrite snowflake crystals falling from the sky this Wednesday? Perhaps huge, indistinguishable blobs of ice crystals falling fast and furious with rapid accumulations. Let us know...

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