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Footsteps
April 2005 by Meiring Beyers

Not a familiar sight in our largely arid location - we close shop, fake illness, pluck kids from school and rush to the higher elevations of the surrounding mountains during particularly icy spells. We clog the skirts of remote roads with unfamiliar traffic to wade in the soft and spellbinding stuff. More intrepid explorers battle frozen oceans to cross polar deserts, measuring their physical and mental strength across its expanses. And a few scientists like me even spend their completely unnatural academic lives studying it. Snow.

Years ago, reading “Miss Smilla's feeling for snow” by Peter Høeg I came across life in places where snow is a constant presence, either as a tranquil landscape or more often as an obstacle to progress.

A small fraternity of unruly researchers study all aspects of snow and once in a blue moon gather to discuss their findings; or lack thereof. I recently found myself in their midst in Davos, Switzerland. How did this happen? For obvious reasons there is interest, probably more skepticism, in the first African presence this “Snow Engineering” conference has ever seen.

With a supporting government grant my fellow SA researchers and I studied the formation of snow drifts and snow dunes, better known as sastrugi, that develop around man-made obstacles. This is important for our continued activities at the permanent research station, SANAE IV, in Antarctica. This research takes me, a self-confessed obsessive of all things remote to wild places, from Dronning Maud Land, Antarctica to a tiny frozen lake called Tornetrask in the Arctic Circle in northern Norway. My particular interest lies in the processes of wind-driven snow.

I wanted to understand its physics and model, or simulate the process by means of mathematics. This allows my team and I to predict and even visualise snow drifts around structures such as SANAE IV. It allows us to minimise our impact on the environment and even design safer habitations for those lonely Vikings in Hammerfest.

The shape of a newly formed snow crystal is determined by the rate of crystal growth which, in turn, depends on the temperature and humidity of the atmosphere. In nature, hundreds of different shapes are found that may be classified as hexagonal plates (the shape we seem most familiar with), hexagonal columns (small pillars or needles with hexagonal cross sections), hexagonal pyramids (rare pyramidal particles), triangular plates (think nachos) and twelve sided plates.

When these crystals develop in the atmosphere, the laws of nature dictate that they drop in for a visit. And then, as sure as death and taxes, we begin our interaction with them. Snow may silently settle during windless conditions, drifting to earth as gravity wrestles with particle drag and atmospheric forces. It may be transported by local winds, described as an Aeolian process, named for the Greek god of wind, Aeolus.

All the while, the snow particles collide with each other and surrounding obstacles - the snow particles are bent out of shape during this aerial, dodgem car-like bonanza. The delicately shaped crystals are quickly deformed into amorphous shapes, like small particles of sand. Surface snow is also constantly transforming; a freshly fallen snow pack surface will consist of lightly packed and connected snow crystals. Temperature and weight result in a spectacular metamorphosis. Particles are bonded together by cooled liquid. Strong enough winds blowing across these snowy terrains disturb the particle inertia and rupture the inter-particle bonds. And we have lift-off.

This is the start of the process called wind-driven snow transportation. For winds less than 60 km/h, the particles travel near the surface. This is called snow saltation meaning “to leap or jump”. The particles skip along, governed largely by gravity, inertial forces and collisions with the surface. You will witness sand saltation following the low and scenic road from Flagstone to Fish Hoek, right on the edge of False Bay beach. Here the sand-saturated south easterlies desperately try to retake the beach lost to tarmac.

Stronger winds initiate suspension, when turbulent effects begin to dominate. These strange eddying motions inherent to atmospheric flows entrain the snow particles to higher elevations. We now have an even more beautiful, more awesome, powerful state of snow transport. When these dancing, saltating, flying snow particles meet an obstacle where wind flow patterns are modified, the snow carrying capacity of the pocket of air changes, causing deposition and erosion.

Once we understood this physical process we developed a mathematical model to describe it. Using computational techniques we can simulate what this spectacular snow show will do when it encounters an object. We can predict the ensuing chaos and graphically depict the development of a snow drift.

In addition and apart from the scientific engineering results obtained, I found something unexpected in this study. A pristine snowy wilderness shows human interaction immediately and severely. A footstep that compresses the snow pack allows winds to scour only the surrounding and non compacted snow, leaving pillars of footsteps extending eerily from the eroded surroundings. Snow talks to us about the precarious and delicate balance of life. Every step and action is immediately permanent. Sometimes it seems that we are trying our best to destroy this planet, raping, pillaging and plundering our ways across sacred oceans and places from Kaapstad to the Kalahari, from Everest to the Antarctic.

Hopefully we will continue to find and allocate more resources to fundamental research into a wide range of weird and wonderful topics concerned with our habitation here. Along the way we will learn to be careful with our more intrusive projects, becoming a little more organic, holistic and simplistic in our approach. That brings me back to Miss Smilla - that snow may not always be an obstacle to our progress, it may also be a witness to our progress, giving us a glimpse of our development or demise.

And snow research from a South African perspective? Not only will at least one researcher have a regular day job when the imminent ice age hits us, but holistically snow is as important, if strange, to South Africans as water is to the nomadic tribes of the Sahara. We desperately just need its undisturbed presence, because of connectivity. The more we can study this concept, the more we can live by it, the more we can appreciate the beauty and fragility of it.