Washington, Jan 18 : A team of mathematicians from UC (University of California) Davis and the University of Wisconsin-Madison (UWM) has developed a 3D computer model of snowflakes.
Snowflakes grow from water vapor around some kind of nucleus, such as a bit of dust. The surface of the growing crystal is a complex, semi-liquid layer where water molecules from the surrounding vapor can attach or detach.
The model, built by Gravner and David Griffeath of UWM, takes these factors, as well as temperature, atmospheric pressure and water vapor density, into account for developing the virtual snowflakes.
Rather than trying to model every water molecule, the computer model divides the space into three-dimensional chunks one micrometer across.
By running the model under different conditions, the researchers were able to recreate a wide range of natural snowflake shapes, which has many shapes observed in nature.
The most common pattern of the computer-generated snowflakes is the "needles", which are also common in the real world.
A shape that is relatively rare, both in the computer simulation and in nature, is the classic six-pointed "dendritic" or feathery snowflake.
Gravner and Griffeath also managed to generate some novel snowflakes, such as a butterflake" that looks like three butterflies stuck together along the body. According to Gravner, there seemed to be no reason these shapes could not appear in nature, but they would be very fragile and unstable.
"No two snowflakes are truly alike, but they can be very similar to each other," said Janko Gravner, a mathematics professor at UC Davis.
"Why they are not more different from each other is a mystery," said Gravner. "Being able to model the process might answer some of these questions," he added.
The 3D model takes about 24 hours to produce one "snowfake" on a modern desktop computer.