Symmetry and Chemistry of Snow: Are Snowflakes Changing Too?


Home / Symmetry and Chemistry of Snow: Are Snowflakes Changing Too?

Typical sample of snow crystals captured with Multi Angle Snowflake Camera. Image courtesy of Dr. Timmothy Garrett and Fallgatter Technologies.

Watching snow fall can be calming, and like any sky phenomenon, snow creation takes place in a natural laboratory.

The formation of snow is a complex process that we may liken to a work of art. However, the way snow forms is more science than art – and current efforts to understand snowfall and the process of crystal formation is a mature science where ‘lab-produced snow crystals’ are routine.

With changes to climate and atmosphere, the symmetry and chemistry of snowflakes are changing; what does the future hold for snow?

Artificial Snow

The first artificially-produced snow flake was grown in the 1930s by Ukichiro Nakaya. Nakaya studied snow flake growth and morphology and devised the system by which we describe most familiar snow: the six-sided symmetrical form. Nakaya understood that the typical snow flake pattern varied with temperature, and water saturation.

Classically, at temperatures near zero degrees Fahrenheit and maximum water saturation, we see the most beautifully-formed crystals, but there is a lot that can interfere with this formation process.

Snow, much like the crystals we grow in a lab, forms from a complex interaction of temperature, substance super-saturation, and crystal nucleation. Unfortunately, growing crystals in a college lab can be comparable with the realities of the natural laboratory of Earth. For all of us who remember growing crystals as freshmen in college, the attempts to coax stubborn crystal growth in a complex mixture may seem extraordinarily frustrating – there’s so much that can go wrong.

Although it can be difficult to synthesize, crystal growth is a natural process that illustrates nature’s complexity. In some cases, non-ideal crystals form (impure crystals) and the non-ideal crystals incorporate impurities that make the crystals seem like a mess. In the hands of expert researchers, the interconnections between ‘impure crystals’ and current snowfall we can observe paints an alarming picture of climate realities.

Shown here are magnified versions of snowflakes in the winter of 1902. Image courtesy of Wilson Bentley.

Shown here are magnified versions of snowflakes in the winter of 1902. Image courtesy of Wilson Bentley.

Snow Fall Patterns and Structure

New aerosols in the atmosphere affect snow fall patterns and types of snow crystals, and worsening air quality adversely affects snow fall and precipitation, as well. In terms of (snow) crystal quality—it becomes harder to make a pure (snow) crystal if your crystalizing solution has items that can affect crystal growth.

  • According to research findings by Dr. Kenneth Libbrecht and co-workers at the California Institute of Technology, chemical additives affect the manner of snow crystal growth. In two review papers detailing his work (one dealing with the physics of snow crystals and another with the chemical influences of ice-crystal growth)— increases in pollutants (e.g. organic molecules) alter crystal growth patterns. His current findings show that it takes “large amounts of critical pollutants” that seemingly affect snow flake structure. At first glance, it would suggest that molecules that can affect hydrogen bonding may alter the snow crystal growth—while molecules that are may be more carbon loving (or nucleophilic—it seems) alter crystal growth far less.
  • Dr. Timothy Garrett, of the University of Utah, reveals the complexity between pollutants and snow (or precipitation in general). One thrust of his research focuses upon imaging snow fall in real time. His patented instrument reveals that snow crystals are increasingly complex and may be less common due to an increase of atmospheric aerosols (e.g. pollutants).

The realities of a post-industrialized society dictate that the changing climate has affected snow fall.

The Future of Snow

Although we can reproduce snowflakes in the laboratory, the processes of snow fall have grown more complex. However, the weather is much more variable than the environment in a laboratory; the weather affects all—what if key agricultural regions continue to receive a small amount of precipitation? –There may be other questions as well, can we affect precipitation or snowfall in drought-stricken regions?

These questions, seemingly profound yet simple, have puzzled scientists and farmers for years. Surely when one looks at snow crystals and notes a changing morphology within only decades of observation, then we are duly challenged to rise to a new level of action and awareness.

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