WEST LAFAYETTE, Ind., Dec. 8 (UPI) -- A U.S. doctoral student says a snowflake's structure is largely determined by a thin layer of water on a snow crystal.
Purdue University analytical chemistry researcher Travis Knepp said by better understanding the physical structure of the snow crystal -- how it grows and why it takes a certain shape -- scientists can get a better idea of the chemistry that occurs on that surface.
Knepp, along with Professor Paul Shepson, is studying snow crystals and why sharp transitions in shape occur at different temperatures.
"On the surface of all ice is a very thin layer of liquid water," Knepp said. "Even if you're well below the freezing point of water, you'll have this very thin layer of water that exists as a liquid form. That's why ice is slippery. Whenever you slip, you're not slipping on ice, you're slipping on that thin layer of water.
"The bottom line is that the thickness or the presence of this really thin layer of water is what dictates the general shape that the snow crystal takes," Knepp said. "Until now, nobody knew that the quasi-liquid layer had such a significant role in determining the shape of snow crystals. Our research clearly shows this to be the case."
The findings appeared in the Oct. 16 online journal Atmospheric Chemistry and Physics. A downloadable version of the article is available at http://www.atmos-chem-phys.net/9/7679/2009/acp-9-7679-2009.html.
