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Snowflake on a Stick
This is a neat trick for making designer snowflakes in the laboratory. First I grow thin ice needles by applying 2000 volts to a central wire (near the bottom of the photo).

After making the needles, I turned off the high voltage, and then ordinary stellar snow crystals grew on the ends of the needles.

This time-lapse video shows a stellar snow crystal growing on an electric needle. It took 20 minutes to make this crystal, plus another minute or so to make the electric needle.

How does it work?
The basic idea is to use strong electric fields to modify the ice growth behavior, a technique that was discovered in 1963 by Basil Mason and his collaborators at Imperial College London. We made some advances in this technique in our lab as well, improving the needle production and making it more reliable. The high voltage produces strong electric fields around an ice needle tip, which pulls in more water molecules from the air, thus making the tip grow faster.

The physics details are seriously complicated, and are provided in the references below.

The process is almost magical to watch. I start with a thin wire covered with frost crystals. Then I turn on the high voltage, and in a few seconds several needles grow rapidly out from the wire. Near the tips, the needles are maybe 100 times thinner than a human hair!

These two videos show the growth of electric needle crystals in real time ....

1st video:  small - medium - large

2nd video:  small - medium - large

Stars, sheaths, and blocks
Once I make some electric ice needles, I can then grow many different kinds of snow crystals on their ends. These were all grown at different temperatures and supersaturations, in keeping with what one expects from the snow crystal morphology diagram.

We are using this technique to better understand how these crystals grow, and why they have the shapes they do.

The hardware
Alas, putting all this together is not a quick weekend project. It took me several years and about ten thousand dollars to get it all working, and there is no faster, cheaper, easier way to do it (that I know of, anyway; if there were, I would have done it that way!). 

Making snowflakes is an unusual occupation, and I am currently the only person in the world studying snow crystal growth using electric ice needles.

Some References

A basic mathematical description of the electric ice growth instability is given here:
Electrically induced morphological instabilities in free dendrite growth, by K. G. Libbrecht and V. M. Tanusheva, Phys. Rev. Lett. 81, 176 (1998).

A longer, more detailed mathematical treatment is given here:
Electrically enhanced free dendrite growth in polar and non-polar systems, by K. G. Libbrecht, T. Crosby, and M. Swanson,  J. Cryst. Growth 240, 241 (2002).

A description of the laboratory hardware used to make these crystals is given here:
A dual diffusion chamber for observing ice crystal growth on c-Axis ice needles, by Kenneth Libbrecht, arXiv:1405.1384 (2014).