Why does a snowflake have six sides?

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Discussion Overview

The discussion revolves around the structural symmetry of snowflakes, specifically why they exhibit a six-sided shape. Participants explore the underlying reasons related to molecular arrangement, the behavior of water molecules during snowflake formation, and the factors influencing the symmetry of the snowflake's arms. The conversation touches on theoretical aspects of crystallography and the conditions under which snowflakes form.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that the hexagonal shape of snowflakes is due to the polar nature of water molecules, which leads to their arrangement in a hexagonal ring.
  • Others suggest that the symmetry of snowflakes mirrors the underlying ice crystal structure, which is hexagonal in nature.
  • One participant questions how water molecules know where to attach on the snowflake, noting that a molecule on one limb does not have knowledge of the structure on the opposite side.
  • Another participant mentions that the exact shape of a snow crystal is influenced by the path it takes through the clouds, leading to synchronized growth of the six arms.
  • Some participants share resources and links to external sites that provide additional information on snowflake formation and structure.
  • There is a mention of the variability in snowflake shapes, with the assertion that no two snowflakes are identical due to differing paths through the clouds.

Areas of Agreement / Disagreement

Participants express a mix of agreement and uncertainty regarding the mechanisms behind snowflake symmetry. While some points about the hexagonal structure are acknowledged, questions remain about the specifics of molecular attachment and the factors controlling the growth of the snowflake's shape.

Contextual Notes

There are limitations in the discussion regarding assumptions about molecular behavior and the lack of detailed exploration into the conditions affecting snowflake formation. The discussion does not resolve how individual water molecules coordinate their attachment to maintain symmetry.

Who May Find This Useful

This discussion may be of interest to those studying crystallography, meteorology, or anyone curious about the physical properties of snowflakes and their formation processes.

barryj
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Probably everyone has heard that a snowflake has six sides. I wonder why. It is reported that since the water molecule is polar, the molecules arrange themselves in a hexagonal ring. I wonder why 6 sides and not 4,5,7,8,9,... etc. Also.as a water molecule approaches a developing snowflake, how does it know where to attach itself. The molecule on one limb of the snowflake does not have any idea of the structure of the other side, does it?
 
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As phinds mentioned, the snowflake symmetry mirrors the underlying ice crystal structure (hexagonal). An excellent site:

http://snowcrystals.com/
 
I did not know of these sites. Thanks to both of you.
 
barryj said:
I did not know of these sites. Thanks to both of you.
Google is your friend. I just cut/pasted your question into Google and found the answer for you. Took about 3 seconds.
 
I went to Google and viewed some reply's. However what bugs me is when a snowflake is forming why does each leg appear symmetrical. A water molecule that is going to attach itself does not know the structure of the flake on the other side, or the other 5 legs. I can see why the original hexagonal ring forms but after that what controls the shape?
 
barryj said:
can see why the original hexagonal ring forms but after that what controls the shape?

that was answered in that page Andy posted

The exact shape of the final snow crystal is determined by the precise path it took through the clouds. But the six arms all took the same path, and so each experienced the same changes at the same times. Thus the six arms grow in synchrony, yielding a complex, yet symmetrical shape. And since no two snow crystals follow the exact same path through the clouds as they fall, no two look exactly alike

go back to his link and read the section on Snowflake Science

cheers
Dave
 

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