Scientists See Snowflakes Like Never Before with New Microscope

Picture in your mind what a snowflake looks like. Maybe it's something like this?

That's what I always thought, too. Then, one winter, I visited the laboratory of William Wergin and Eric Erbe in Beltsville, Maryland. They put snowflakes under a special microscope to magnify the flakes many thousands of times their actual size.

		Why bother magnifying snowflakes anyway?
		It's part of the standard lab procedure for testing a new microscope.
		It might help farmers grow their crops.
		It's a good way to kill time on a slow day.

Magnifying snowflakes can reveal clues about how much water is in fallen snow. And snow is the source of most of the water in the American West used for drinking, watering crops, generating electricity and other uses--from water slides to fish tanks!

For example, information about how much water is stored in the western snowpack is crucial to farmers in thirsty states like California. The farmers need to know how much water will be available for watering their crops.

The Beltsville scientists do more than just magnify the snowflakes. They photograph them, too. But instead of using a regular camera, they "shoot" the flakes with a beam of electrons.

After seeing some of their photos, I have to say that now I really do believe "no two snowflakes are alike!"

What convinced me? See for yourself! The flake shown at the story's beginning is called a dendrite. But as you can see, the icy shapes in the photo at left are a lot different. When I first saw them, I thought of an hourglass, a concrete birdbath or perhaps a column from an ancient Roman ruin.

"Snowflakes are actually made up of two to several hundred snow crystals," Wergin explains.

What makes the crystals look so odd? How do they get glued together at such crazy angles?

A lot depends on temperature and how dry or moist the air is. As a crystal tumbles to earth, it can crash into or fuse with other falling crystals. Or a bunch of crystals may melt and then refreeze in a funky new form.

For years, scientists photographed snow crystals using a regular microscope hitched to a camera. But they had to race against time. That's because the crystals melted quickly. Wergin and Erbe solved this problem: they put the crystals in a deep freeze. Really deep: about 320 degrees F below zero. What's the "F" mean?

So how do the scientists photograph snow crystals? First they catch the falling crystals on a small, frozen chip of copper. Then they dip their "catch" in a container of liquid nitrogen. This can preserve the crystals for months. Next, they spray the crystals with a coating of gold or some other metal.

		Now why do you think they would do that?
		They won't have to worry about the flakes melting.
		When they're finished with their experiments, they can make unique and attractive necklaces and wind chimes.
		The gold makes the crystals shiny, so they show up better under the microscope.

When the scientists are ready to get up close and personal with these metal-wearing crystals, they stick them in a high-tech gizmo called a scanning electron microscope, or SEM. This is no ordinary microscope--it's much, much more powerful.

The SEM shoots an invisible beam of electrons onto the crystal's metal coat. This knocks off the crystals' own electrons--much like shaking dust from a rug. The SEM "sees" this electron "dust" and captures an image of it.

--By Jan Suszkiw, Information Staff, Agricultural Research Service

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