Snowflake Microscopy: The Steps

Many people might think that viewing snowflakes under a microscope might be an impossible task, but this is not the case. Whilst a difficult and precise process, with the proper preparation and measures taken, this can indeed be done. 

Snowflake Microscopy: The Steps

But what are these steps, and what exactly can we learn from snowflakes in the first place?

“Snow Science”: A History

The Chinese are thought to be the first to have officially described snow. In his 135 BCE publication Disconnection, Han Ying describes the visual similarities between snowflakes and flowers, noting the symmetry and shape as being uniform and visually pleasing. 

This was furthered in 1250, by German philosopher and scientist Albertus Magnus, who provided what is considered to be the earliest European account of snow. 

In 1611, German astronomer and mathematician Johannes Kepler made attempts to explain the hexagonal shape of snow crystals.

These attempts were supported in 1675 by Friedrich Martens, a German scientist who identified and cataloged 24 different types of snow crystals

However, it wasn’t until 1894 when snowflakes were photographed under a microscope, when A.A. Sigson collated a series of images. 

Japanese physicist Ukichiro Nakaya conducted extensive experiments and research into snowflakes in 1932, recreating a snowflake artificially, and theorizing the process of water vapor saturation and its relationship to environmental temperature. 

This was known as the Nakaya Diagram, later improved upon by Teisaku Kobayashi in 1960, when he verified and streamlined the theory, creating the Kobayashi Diagram, which was again refined in 1962. 

As space travel progressed through into the 1980s, attempts were made to artificially synthesize snowflakes in space, and successes were made by the crew of the Challenger space shuttle in 1983, and Yoshinori Furukawa in 1988. 

The Facts About Snowflakes 

Snowflakes are formations of crystalized ice which achieve a specific size, and then fall through the Earth’s atmosphere as snow. 

Whilst snowflake is a term we all use, this technically refers to larger formations of ice crystals which form puffs, or flakes.

When it comes to the intricate patterns commonly associated with snowflakes, these in fact represent only a single crystal. This is why scientists refer to these singular flakes as “snow crystals” for a more specified accuracy. 

How Are They Formed?

Each snowflake, or snow crystal, is formed around a single particle of dust, which attracts supercooled water droplets from clouds thanks to a supersaturated air mass. 

These then freeze due to the high altitude, and freeze as ice crystals. Once these gain sufficient size, they fall down as snow. 

Are Snowflakes Really Unique? 

The way in which they fall to Earth, and more specifically, the number and combination of different temperatures they pass through on their journey, causes the formation of intricate, delicate patterns, usually based around a six pointed symmetry. 

Whilst this occurs to such a degree that all snowflakes do have a distinct individuality, there are 8 groups within which they can generally be classified.

Within these groups there can be anywhere up to 80 different variations, despite all sharing the same physical makeup and possessing elements of the same patterns. 

The Classification Of Snowflakes

When classifying snowflakes, there are 8 distinct categories which scientists have devised as a means of grouping them together. Whilst there are always variants and anomalies, most can be attributed to the following groups. 

Needle Crystals

These are represented by the letter N, and are fairly simplistic patterns of needle like strands of ice. 

Columnar Crystals

Categorized with the letter C, these can be separated into two distinct subgroups, namely simple, and combination column shapes. 

Plate Crystals

Identified by the letter P, these can be subdivided into: a regular crystal in one plane, plane crystals with extensions, crystal with irregular numbers of branches, crystals with 12 branches, crystals which have been malformed, and crystals with a radiating assemblage of plane branches. 

Columnar/Plate Crystal Combinations

Referred to as CP, these formations can be subdivided into: columns with plane crystals at either end, bullets with plane crystals, and plane crystals that have spatial extensions at either end. 

Columnar Crystals With Extended Side Planes

Identified with the letter S, these can be subdivided into: side planes, “scale-like” side planes, combinations of side planes, bullet patterns, and column patterns. 

Rimed Crystal

Identified as the letter R, these can be separated into: rimed crystals, densely rimed crystals, “graupe-like” crystals, and “graupels”. 

Irregular Snow Crystals

Identified as I, these can include: ice particles, rimed particles, broken shards from ice crystals, and other miscellaneous formations which have no distinct pattern. 

Germ Of Snow Crystals

Finally, this category is represented by the letter G, and can include: small columns, germ of skeleton forms, small hexagonal plates, small stellar crystals, small assemblage of plates, and irregular germs. 

The Structure Of Snowflakes

In terms of their basic structure, snowflakes are composed of a central facet, which tends to be 6-sided, and then extending struts from each side, which then change according to environment. 

Perhaps strangely, snowflakes form in similar ways to actual cells, in that they have a somewhat (and mostly) uniform pattern, center themselves around a central particle of aerosol, or “nucleus”, and attach themselves to one another to form tighter formed structures. 

Nucleus

This nucleus, as we have called it, is the initial particle of dust or aerosol that is required for the formation of supercooled water particles to attach themselves to it under the freezing mass of the air at high altitudes. 

Whilst not a nucleus in the scientific sense, in that it has no function of control over the snow crystal, it does form the central growth point wherein the water particles can attach themselves, freeze, and form ice patterns. 

There are, however, specific environmental circumstances where this can take place. 

Firstly, the temperature must be below -35 C (-31 F) for the nucleation of these droplets to occur. And even then, not every type of particle is appropriate. 

For example, the creation of artificial snow is done using particles of silver iodide and dry ice, and this has been shown to be effective under the right conditions.

Similarly, it is thought that clay, desert dust, and other biological particles may be effective, but it is not known to what extent this is true. 

Crystal Growth

The important thing to remember, is that this process happens in supersaturated environments.

This term can be complex to explain, but essentially a supersaturated state is when solids particles are present within a liquid, but are not in currently suitable conditions for solubility to occur one way or another. 

For example, in this scenario, the dust particle would be saturated by the water, essentially submerged within it. If this was to happen on the desert floor just after a heavy rain, the subsequent heat of the desert would cause the solid to dissolve within the liquid. 

However, in high altitude clouds, where the temperature drops to well below freezing, the liquid instead freezes, forming to and around the particle of dust, and forming crystal patterns.  

This is aided by a process called the Wegener-Bergerton-Findeisen process. This is when the ice crystals grow as a result of water vapor provided by cloud droplets.

This creates larger cloud droplets at the expense of the smaller droplets, without draining the vapor from the air in between. 

As these ice crystals grow, they can separate, split, and bump into one another, forming a series of new ice crystals. The effectiveness and range of this “ice enhancement” is of course dependent on the sizes and shapes of the formations. 

Crystal Appearance

When it comes to the appearance of the snow crystals, there are several things to say in terms of color, and shape. 

Whilst ice itself is generally thought to be clear, in that it is transparent and we are able to see through it, the color of snow is generally seen as white. 

This is because the snow crystals themselves act as light prisms, which can harness the sunlight, reflecting within themselves off their varied axises, and giving off a white hue. 

Similarly, the shape of the crystal patterns are determined greatly by the temperature and humidity during formation. Despite their common association with symmetry, most snow particles tend to be irregular, at least on some level. 

This is because, whilst the individual snow crystals can achieve some semblance of uniformity, the process of bonding with other crystals and forming snowflakes turns them more into clusters, which are then greatly affected and reshaped on their unpredictable fall to Earth. 

That being said, the formation of individual snow crystals does tend to follow a six fold radial symmetry, due mainly to the hexagonal crystalline structure that ice adheres to. 

From this initial formation, the arms of the snow crystal, or dendrites, then form their own somewhat symmetrical patterns in turn, forming larger structures. 

The Microscopy Of Snowflakes

Snowflake Microscopy: The Steps

Studying snowflakes has always been difficult, simply due to the fact that they are extremely fragile and temperature sensitive. 

As such, methods needed to be made to facilitate this. 

Magnifying Glass

As a starting point, and certainly before the invention of the light microscope and its subsequent descendents, magnifying glasses were used to study the formations and structures of snow crystals. 

This was done by using a magnifying glass, and by placing the snowflake on a piece of black card, to best highlight the details. 

When doing this, time is of essence, so as soon as it starts snowing, take the piece of black card and attempt to catch some samples on its surface. Then immediately use the magnifying glass to examine the captured samples. 

With this method, it is best to avoid breathing on the card, as this will melt the ice. As such, covering the nose and mouth, such as with a face mask or scarf, can be a sufficient way to ensure the crystals last for the longest possible time during examination. 

When observing the samples, you might notice that differing patterns are present in different snowflakes. But whilst they all present a different pattern, they all boast a uniformed symmetry. 

Stereo Microscopes

Of course, if you are using slides to capture samples, then stereomicroscopy is the way to properly view them. 

You can also use a digital microscope camera to capture these images for permanent cataloging. This will ensure you have a record of your findings long after the obtained samples naturally degrade. 

Priming the microscope is a delicate procedure, and involves having the right settings in order to achieve maximum efficacy. 

First, adjust the revolving turret to allow the lowest power objective lens to come into position. Then place your chosen slide on the platform beneath it, using the clips to hold it firmly in place at either end. 

Then you are ready to examine the sample. To do this, look through the eyepiece, and adjust the magnification once more, using the revolving turret to zoom in until you have the best degree of clarity. 

You can also move the slide around to view different angles and parts of the sample. When doing this, however, do it with care, as you want to protect the integrity of the slide and the captured sample within. 

Then comes the time to record your observations. This can be done with the above-mentioned microscope camera, if you have one, and it is also advisable to take accompanying notes to refer to specific details, thoughts, and findings you have discovered during the examination process. 

This process is the best for achieving detail and clarity, and it can let you examine a snow crystal to a degree once thought impossible. 

When observing the sample through these microscopes, you can properly see the intricacy of the patterns, and the degree to which the formations differ and adhere to one another.

This is another reason why having multiple samples is important, as it allows you to make much more accurate comparisons. 

Preserving Snowflakes

If slides and microscopy are your chosen methods, then it is important to know how to properly preserve a sample for later examination. 

Due to the fact that snowflakes can easily melt at room temperatures, bringing them inside for further study can be as equally tricky as capturing samples in the first place. 

However, there are two methods that can be used to prolong their lifespan for further examination. One method involves using hairspray or a coating of acrylic, and the other involves using a non-gel superglue to lock the sample in place. 

Hairspray/Acrylic

When using hairspray or acrylic to secure the sample, the first thing you will need is a glass slide and some spray. Put some of the hairspray on the slide, before holding the sticky side towards the sky to catch some samples. 

Once you have done this, put the slide in a box and keep it cold for several hours. Once it has sufficiently cooled, the spray will have dried, the water will have evaporated, and the snowflake will have disappeared.

However, an impression of the snowflake will remain on the slide. 

A similar process can be achieved using the acrylic. Polyvinyl plastic will work best, and this can be mixed into a weak solution to capture an impression of snowflakes. 

Coat the slide in a thin layer of the acrylic, then chill the painted slide at a temperature of around 2 degrees below freezing. Then, when it starts to snow, place the painted side facing up, allowing samples to be captured.

Then store the slide in a cold place to let the solvent evaporate, before placing the slide in a warmer place to melt the snowflake. 

This will leave a successful impression that can be studied. 

Non-gel Super Glue

The second method is to use non-gel super glue. Whilst the above method will simply catch an impression, using a non-gel super glue will capture and preserve an actual snowflake for examination. 

Whilst this is still not permanent, you can capture the sample for a longer period of time, allowing for more extensive study and experimentation. 

First and foremost, the glass slide needs to be chilled, as do the tools (tweezers, cover slips) and the super glue itself.

A thin form of pure cyanoacrylate is perfect for this job, and once it and the tools have been cooled to around 20 degrees fahrenheit, before beginning the process. 

To do this, place the glue on the slide, using only a thin layer so as not to degrade the sample.

To capture the snowflakes you can either use a blank slide, or for a more accurate selection, you could use some black paper or card to catch the snowflakes, and then use the cold tweezers to select an individual sample to be placed on the glued slide. 

It is best to do several of these at any one time, as this not only gives you scope when it comes to experimentation and study, but you will also get a better understanding of the unique formations snow crystals can adopt. 

Once you have a sample on the slide, gently lay the coverslip down on top, using an angled approach to avoid trapping bubbles of air between the two pieces of glass. 

Once you have done this, the only thing left to do is to store the slides in the freezer for a couple of weeks to properly preserve and secure the samples.

After this time, you may notice that the snowflakes are white in color, a symptom of the refractive effects of their prism-like infrastructures. 

Final Thoughts

And there we have it, everything you need to know about snowflakes and the best methods to collect and examine samples. 

The most important things to remember are that patience, temperature control, and care are required if proper samples are to be taken. 

This means keeping your breath away from the collected snowflakes, chilling the slides, adhesives, and tools before the process, and ensuring all slides are stored at the appropriate temperature to ensure longevity. 

Most of all have fun, and prepare to be amazed by these fascinating natural occurrences!

Jennifer Dawkins

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