Iain Cameron: he really knows snow
Many of us love hillwalking in winter, but how much do you actually know about the white stuff? Trail asked an expert to reveal some amazing facts about snow...
Iain Cameron (left) knows A LOT about snow. He photographs it, measures it, writes about it and generally spends most of his spare time in it, on it or looking for it. The Royal Meteorological Society publishes his research and he has co-authored a book on snow.
Having inspired and amazed with his snow-based discoveries in the UK, Iain’s obsession has also revealed dramatic and changing weather patterns. For hillwalkers, snow spells beauty, fun and danger in equal measure. Heading out on a trail with the crunch of glittering névé underfoot can transform a great day into an unforgettable experience; but how much do we know about snow in the UK? A keen Scottish-based hillwalker himself, Iain reveals some fascinating aspects of the white stuff that every outdoor enthusiast should know.
Snow has vanished completely only five times in Scotland since the late 1700s
1 BRITISH SNOW CAN BE VERY DEEP
…and we’re not talking ‘enough to make a snowman’ deep. In exceptional years snow depths can reach 75ft (25m) on Ben Nevis and Braeriach, and in 1951 we had the snowiest winter of the last 100 years, with depths up to 100ft (30.5m) in the Cairngorms’ Garbh Choire Mor.
Iain says: “You tend to find that the deepest snow is on north-east-facing aspects and has come in from the Atlantic; though this isn’t always the rule, as deep snow can come from the continent, too. The snow will blow in from a south-westerly direction, and it’s this wind that causes the very deepest drifting and enables snow to pile up and reach greater depths. This can be supplemented by avalanche debris and spindrift (basically snow that hasn’t bonded and drifts like a river in windy conditions).”
2 SNOW CAN LAST A VERY LONG TIME
Snow has vanished completely only five times in Scotland since the late 1700s: in 1933, 1959, 1996, 2003 and 2006 (note the last three occasions were all in the last 20 years). The lowest patch of snow ever to survive in Scotland from one winter to the next was at 725m altitude, on Aonach Beag near Ben Nevis. What’s more, long-lasting snow isn’t just found in the north. Further south and more recently, at Eldon Hole in the Peak District, snow persisted to winter 2011/2012 from the previous one. In 2010, an open snow patch at Carnedd Llewelyn in Wales lasted until 28 June. Typically snow in England melts in May or June, normally going last at Helvellyn’s Brown Cove.
Iain says: “Because the prevailing weather in the UK comes from the south-west, gullies and corries that face north-east offer a lot of protection to the snow because they shelter it from the mild wind. There have been plenty of times I’ve been on a summit and it’s been blowing at gale force, but as soon as I step into the shelter of a north-east-facing corrie there’s virtually no wind at all. What’s more, tall north-east-facing cliffs can offer a lot of protection from solar radiation. The classic example is Ben Nevis, whose cliffs are taller than 1,000ft; in most months of the year, no sun shines on the sheltered gullies. These large patches of semi-permanent snow can create their own micro-weather system, where the air around the snow is significantly cooler than the surrounding area.”
3 SNOW CAN PROVIDE GREAT SHELTER
While snow can often be seen as an added danger on a hillwalk, the truth is that it can actually be a lifesaver. If you become stuck out on an exposed ridge, a snowhole can buy you precious time to wait for rescue. Iain says: “Snow is a very, very good insulator because it protects against the wind. That’s why people use it for shelters and igloos. Of course, this is relative – snow in itself is not warm, and you couldn’t sit in a snowhole in your T-shirt. However, compared to the temperature outside in a gale, it’s far warmer. Humans aren’t the only ones to take advantage of snow to make life more comfortable. If it gets really cold at night, ptarmigan will dig a little hole and roost in the snow. At the other end of the spectrum, in summer red deer often use large snow patches to lie on to cool themselves down.”
4 1951 WAS A GOOD YEAR FOR SNOW
Older readers with good memories will recall that the first day of snow recorded in 1951 was 1 January and the last wasn’t until 30 April. Remarkably, Bournemouth on the south coast of England saw 10 inches of snowfall, while Lowestoft on the east coast had a whopping 14 inches. This was also a challenging time for hillwalkers in Europe: in what was dubbed the ‘Winter of Terror’, 649 avalanches killed 256 people. Other big years include 1933, which saw 48 hours of continuous blizzards; and 1963, when the Thames froze for the first time since 1880.
5 IT CAN SNOW ON ANY DAY
Snowy weather isn’t restricted to the dark winter months, and those visiting higher peaks need to prepare and pack accordingly as they could need crampons instead of sunscreen.
Iain says: “It can snow on any day of the year on Ben Nevis. In fact, it snowed on 1 July this summer, while the temperature during July in London reached a blistering 27 degrees! There is definitely a difference in temperature between base and summit. Although there is no absolute rule, this is often around 10 deg C. So in Fort William it could be 15 deg C, but up on Ben Nevis you could be looking at temperatures of 5 deg C. There are some occasions when you can see a reverse in temperatures: if there’s been a hard frost in the glen below, the summit can be a number of degrees warmer.”
6 SOME SNOW PATCHES HAVE NAMES
Given the geographical traits that make for ideal settings for snow, it shouldn’t be a surprise that some patches take the same form every year. Their persistence and number is a source of close attention even to the extent that some patches have local names. Thanks to its altitude and latitude, it’s in Scotland’s Cairngorms that you’ll find the areas where snow persists longest, and in more locations, than anywhere else in the UK. Ben Macdui, Cairn Gorm and Braeriach all contain long-lying patches that have been observed for many years. One such is even named on the OS 1:25k map: the Cuidhe Chrom (‘crooked wreath’) that occurs on the northern flank of Ben More, near Crianlarich.
7 UK WINTERS CAN BE VERY DANGEROUS
While snow is unmistakeably beautiful to look at, photograph and walk in, it can present challenges and should always be treated with caution and respect.
Iain says: “British weather is very fickle; and because of our proximity to the Atlantic Ocean, conditions can change very quickly. I wouldn’t say weather in the UK is more dangerous than in other countries, but it’s certainly more temperamental! Hillwalkers need to pay particular attention to weather forecasts in this country because it can change so fast – and even more so in the winter and with snow involved.”
...the first day of snow recorded in 1951 was 1 January and the last wasn’t until 30 April.
8 RE-GLACIATION COULD HAPPEN, BUT NOT SOON
With snow patches recorded at depths of up to 75ft and temperatures dipping to lows of -27.5 deg C as recently as 1995, just how cold would it have to get for glaciation to occur and for scenarios seen in films like The
Day After Tomorrow to play out in real life? Iain says: “I’m not a climatologist, but I have read research on the subject and you would be looking for a overall drop in average temperature of at least 2 deg C for the process to even begin. And this doesn’t mean you’d see glaciers all over Scotland; instead you may see the start of glaciation or permanent snowfields. We’re very unlikely to see glaciation in Scotland or the rest of the UK any time soon.”
9 SNOW CAN BE DRAMATIC!
Snow tunnels (see pages 64-65 and above) can be found on Scottish mountains, created by water burrowing through a snow drift. The wind then takes over and blasts through the space created by the water, enlarging the tunnels over time. They become so big that you can walk through them – although caution should always be taken as the tunnels eventually collapse.
I wouldn’t say UK weather is more dangerous than in other countries, but it’s certainly more temperamental!