|David Monteith enjoying early season conditions on Milky Way (III)|
Coire an Lochan, Cairngorms, November 2010. Photo: Alasdair Monteith
Such a change in activity requires more than just a cursory glance at weather forecasts and an idea of a venue (although the Mountain Weather Information Service is the place to go for reliable weather forecasts all year around for 8 mountain areas across mainland Britain).
Winter days in the mountains can bring some of the most rewarding and exhilarating experiences when stunning weather, good routes and excellent banter all come together. However, they can also bring fear, danger and worse - injury or death, if the cards are stacked against you and decisions don't go your way.
From a geography point of view, winter presents a wealth of interesting physical processes to look at, explore and enjoy. The weather is often unpredictable and brings disruption as well as fun, and although weather forecasting is improving snow events like the December 2010 covering are hard to predict.
|Ski touring Yorkshire style: Andy Saxby taking advantage of a fairly rare few feet of snow on the North York Moors, December 2010. Photo: Alasdair Monteith|
Snow - more than just a few Ice crystals
The snow pack as the layers of a wedding cake
|Wedding cakes and snow pack. More in common than you'd think.....|
Photo credits: Andy Huddart, wedding cake. Lucy Monteith, snow pack.
In Scotland strong winds are a common occurrence. Snow doesn't tend to stick around on the slope it was deposited on but is transported to the lee ward, or downwind slope, perhaps sheltered behind a ridge or corrie rim. This violent process of transporting snow tends to damage the crystals and deposit large amounts of snow that can be poorly bonded to the underlying layer. It can give off a hollow 'wumf' like sound when loaded and shooting cracks may move out across it when loaded.
Now, at this stage I run out of time so either keep the cake in the kitchen, where the temperature varies from being fairly mild to below freezing (it's a cold mid terrace Lancashire house; below freezing IS possible). Such a variation in temperature in the mountains tends to have a consolidating effect on a snowpack. Freeze thaw cycles result in the layers of our snow bonding together to form a fairly cohesive structure.
However, I could of course put the whole half finished cake in the freezer, I am an amateur cake maker after all. In this consistently cold, dry environment we see the formation of crystals on the surface of the cake. With our snowpack a similar process may occur, as surface hoar on the top of the snowpack, or as a layer of faceted crystals buried within the snowpack (see the photo below for a glimpse of their delicate and intricate structure). These crystals can present a real danger in the form of a hidden weak layer, ready to release when loaded.
|Cold weather beauty: faceted crystals. Photo: David Monteith|
Now I cover my fairly odd looking wedding cake in a final layer of icing. This gives the cake a smooth, white, consistent looking appearance. This is our surface layer which falls as soft, slightly damp snow which quickly freezes over that night forming what is a fairly dense, consistent surface layer. In reality it's a smooth blanket hiding a variety of layers with individual characteristics and instabilities.
Thanks to David Monteith - MIC and IML for the 'peer review'. Check out his website here: