By Toni Cary
I watched it as it tumbled from the heavily laden canopy and middle boughs of the Candlebark. Snow. It fell silently; an endless cascade of mellifluous melt as part of earth’s lifegiving water cycle. Oh the transcience of it all! And yet, a lifetime held in the mind’s eye. It stains your heart and eyes with its beauteous purity; it enriches your life with its breathtaking offerings of adventure.
I stood there, transfixed by this melting moment. It was magic. One by one the glistening green grey leaves on each pale skeletal branch shed their icy adornment, as the warmth of magnificent crepuscular rays exploded across the early morning candy pink sky like the opening scene of earth’s creation.
Plunging my glove into the squeaky below -10 degree depths of the newly fallen powder, I formed a small glittering snowball. The flakes fused together quickly and easily as I pressed and moulded the bright white substance into my little cannonball ready to launch at a nearby boulder. Of course it is impossible to see the incredible crystal makeup of each individual flake. Some flakes are simple, made up of a single ice crystal. Others are much more complex, with some being made up of around two hundred ice crystals that have fused together.
Lake Albina with everlasting daisies
And, it is quiet. The fallen snow acts as a sound-absorbing material. Any noise is minimised over the surface because air is trapped between each crystallised flake that traps sound waves, dampening vibrations. All I can hear is the squeak of my footsteps on the pristine surface and the gentle crunch of my gloves around a shimmering cannonball. Even snow cover as thin as 2cm can alter the acoustic properties of a landscape.
Snow begins its genesis within the clouds, either Altostratus, Nimbostratus, Cumulus or Cumulo-nimbus. This is where the temperature is below freezing (0 C or 32 F), forming around pieces of dirt carried up into the atmosphere by the wind. The ice crystals become heavier and heavier and then fall. The varieties of crystalised shapes are determined by temperature, being either flat plates, long columns or prismic shapes. They are symmetrical six-sided shapes or small and irregularly shaped. They develop differently because of the way the water molecules organise themselves as they freeze. The way the flakes fall also impacts on their shape. If they spin while falling, they could still be symmetrical upon reaching the ground, or if they fall sideways for example, they could become lopsided. It is said that no two snowflakes have exactly the same molecular arrangement. This is true; however they can still look very much alike.
The snow here in the Snowy Mountains of New South Wales, (one of two sub-regions of the en-tire Australian Alps which comprises of an area of 1,232,981 hectares) falls mostly from June through to October. However it is not uncommon for snow to fall on the peaks of the Main Range in mid-summer. Such is the changeable nature of the weather here in the higher mountains, where the temperature in mid winter is capable of plunging to below – 20 C. So far the coldest day recorded is – 23 C at Charlotte Pass in June, 1994.
Snowstorms and blizzards can also occur on and around the peaks of the Snowy Mountains. Snowstorms occur when warm air has to rise over cold air. When the warm air and the cold air are drawn together, a front is formed and precipitation occurs. Warm air can also rise to form clouds and snowy blizzards as it flows up a mountainside; (a blizzard being a snowstorm with high winds).
As well, other tricky phenomena such as black ice (aka clear ice), hail and freezing rain can pose a problem on the Snowy Mountain pathways and roads. This is particularly in winter when snow chains are frequently used for two wheel drive vehicles driving up to the ski-fields. It is virtually impossible to see black ice on the road, particularly if it is surrounded by snow or sleet.
Snowy Mountain creek
Sleet starts as frozen rain, ie rain that falls when surface temperatures are below freezing. A mixture of the frozen rain and snow form ice pellets known as Sleet. Frozen rain is made up entirely of liquid droplets. These raindrops become super-cooled while passing through a sub-freezing layer of air, many hundreds of metres above the ground and then they freeze on impact with whatever they fall on. This ice is called ‘glaze’ which can be up to several centimetres thick. If there is a storm that produces a significant thickness of glaze ice, it is then known as an ‘ice storm’.
Black ice, snowstorms, blizzards, sleet, incredibly high winds, frozen rain, hail or even just plain old snow can cause a multitude of problems for visitors and locals alike. Disruptions in public infrastructure such as electricity supply, road accidents, telephone line interruptions, gas supply problems and a small negative effect on the yearly yield of solar photovoltaic systems is often expected in the Snowy Mountains in the depths of winter months.
However, the various ski-fields in this region depend on the snow to attract huge volumes of visitors each winter (700,000 visitors in NSW p.a. in fact). The snowfields here in the Kosciuszko National Park take in Thredbo, Perisher Blue Ski Resort and Charlotte Pass. And each of these areas have their own winter attractions such as tobogganing, snowshoeing, Cross Country Skiing, downhill skiing or snowboarding to offer their visitors. If the snow doesn’t come nor do the tourists.
So understandably the impact of climate change is always at the back of everyone’s mind. Back in October 2011, in the Sydney Morning Herald, there was a headline that stated, “Bleak future predicted for Alps without Snow”! (D. Wroe) It basically said that the Australian Alps’ ski slopes could be completely bare of natural winter snow by 2050 … unless a concerted effort was made against global warming. According to a government-commissioned report — “Caring for our Australian Alps Catchments” we could be facing an average temperature rise of between 0.6 and 2.9 degrees C by 2050. Furthermore rain, snow and other forms of precipitation will probably decrease by up to 24% within the next four decades. (It is of interest to note that snow cover has already declined by more than 30% since 1954).
So what might happen in the future? What are the consequences of a snowy decline for the Snowy Mountains?
Well, firstly we may experience more bushfires, more droughts, more severe storms and more rapid run-off causing added heavy erosion in the area. Secondly, some of the things that we are seeing already, and will continue to see occuring in the future, will be:
Plants and animals that normally do not belong in this alpine and sub-alpine area.
Less snow or fewer snow covered days in winter
Less rainfall which will reduce flows in alpine streams and further on downstream
Evidence of larger scale and more destructive bushfires
Declines in threatened alpine fauna species such as many different frogs, pigmy possum and the long-toothed rat for example
Increases in weeds and introduced animals such as deer and fox
Changes in seasonal occurrences, and timing of flowering and migration events
Changes in the composition of specialist vegetation communities
Changes in soils and hydrology
Changes in duration and depth of snow cover, and ice cover on alpine lakes
Loss of ecosystem services
Loss of unique flora in alpine areas that cannot adapt (these plants make up 10% of all plants in the Australian Alps).
According to a report prepared for the Australian Alps National Parks, by the liaison committee for the Environment Futures Centre of Griffith University in 2013 (Pickering, Guitart, Ballantyne, Morrison), “The Australian Alps National Parks currently conserve nearly all of mainland Australia’s snow country and are important nationally and internationally due to their conservation values, ecosystem services and economic benefits”. Their predictions for the future include:
Higher temperatures
Reduced snow cover
Increased abundance and diversity of weeds and feral animals
Increased risk of bushfires
Changes in winter and summer tourism.
Add to these impacts on the area, the impact of less snow on the Snowy River and also the Snowy Hydro System, and the future appears gloomy indeed. Putting aside the Snowy Hydro Electricity System, which is an article in its own right, the general distribution of rainfall over the Snowy River catchment is controlled by orographic effects that affect the Snowy River system. Orographic precipitation, also known as relief precipitation, is generally forced by an upward movement of air upon encountering a physiographic upland. Mountain ranges and elevated land masses, such as the Snowy Mountains, have a major impact on global climate. Hydrology, that is, snow melt into rivers in the Snowy Mountains typically have the lowest average stream flow in the months from November to June, with October offering the largest flows of the year – spring melts. The large flows from September and October are derived from snow melt and, hydrologically, it is one of the key aspects that defines the mountain waterways.
The mixed rainfall and snow-melt rivers of the Snowy Mountains, that are also fed by the glacial-remnant lakes of Kosciuszko National Park, can be defined by strong seasonal patterns and re-main so far, permanent througout the year. There is, so far, no record of a zero flow ever being observed in the lower parts of the Snowy River. However, it stands to reason…less snow melt, less precipitation in general… less water in the Snowy River. The impact of this? The absence of an annual snow melt flood allows sediment to accumulate, and weeds such as the Willow and Black-berry, for example, to colonise the permanent sand flats across the river to find a new shallow channel. The river can shrink to little more than a trickle.
But, all is not lost. There is always man-made snow!
First day of Winter
For ‘man’ to make snow, water and cool temperatures are necessary. It’s also apparently good to mix a ‘nucleator’ into the water supply as well. For example, a natural protein named Snowmax is particularly good at attracting water molecules for the purpose of creating good quality snow. A traditional ‘snowgun’ makes water droplets by mixing cooled water and compressed air together. Compressed air atomizes the water. It disrupts the stream of water so that it splits into lots and lots of tiny water droplets. These water droplets are blown into the air and then cooled as they fly through the air. Compressed air is then added to spread the particles so that they move freely. An ‘airless snow gun’ uses simple nozzles to atomise the water into a fine mist. These droplets are then blown upwards high into the air by a powerful fan.
In ‘snow making’ a worker has to remove the water’s ‘heat of fusion’, which is the large amount of heat energy required to change ice into liquid water at 0 C. If the natural conditions outside are cold enough, they are sufficient for freezing the water. However, if the temperature (snow making is usually carried out at night) is not cold enough, ie not freezing or only just below freezing, some additional components will be required to help the process along. Therefore, some snow makers carry special ‘cooling units’ to speed up the freezing process. Easy, right? But what if we experience those higher temperatures in the future, as predicted?
I wonder, as I look up to a brilliant blue sky above me, a ‘blue bird’ day. Will I be holding a snowball in my gloves in ten years’ time? Or will I have to drive another thirty kilometres up to the alpine world of Mt. Kosciuszko and Mt. Townsend to make a snowman; share dwindling snowfields with twenty thousand, or instead, just one thousand people? Will the Candlebark and Mountain Ash surrounding me here in the montane be happy without a covering of thick snow to shed a few times a year? Probably. But I won’t, our eco-system won’t, our native flora and fauna won’t … and Australia won’t.
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