Why does a snowflake have six sides?

[barryj]

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?

 

[phinds]

It has to do with being the most efficient way H20 molecules can join:

http://www.metoffice.gov.uk/learning/snow/snowflake

 

[Andy Resnick]

As phinds mentioned, the snowflake symmetry mirrors the underlying ice crystal structure (hexagonal). An excellent site:

http://snowcrystals.com/

 

[barryj]

I did not know of these sites. Thanks to both of you.

 

[phinds]

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.

 

[barryj]

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?

 

[davenn]

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