The Angry Corrie 62: Jul-Sep 2004

Striking tales of lightning

The early part of May this year saw a series of vicious electrical storms hit the southern Highlands, culminating, on 10 May, in a particularly nasty affair that spent much of the afternoon working its way across the country. One walker - Derek Hunter from Kelty - died after having been struck by lightning on Ben Oss. Two others had also been struck - but survived - on the Cobbler on 5 May. The 10 May storm was almost certainly the worst of its kind to hit the Scottish hills since 14 May 1998, when similar meteorological mayhem cost the life of Nick Kehoe in the Fannaichs (although he may have walked/stumbled over a crag while attempting to escape the weather, rather than having been hit by the lightning itself). That storm, like the recent one, was slow-moving and widespread. People suffered near-misses in various parts of the northern Highlands, none more so than Lindsay Munro, who here recalls his feelings and his ongoing fears. As to the wider question of how to spot, avoid and generally deal with such storms, Grant Hutchison offers some thoughts across the page.

THURSDAY 14 MAY 1998 started in fairly typical fashion, as hillwalking trips go. Rita and I left Perthshire at 6am to drive to Achnashellach. Our objective for the day was a circuit of the Coire Lair Munros and by 9:30am the boots were on and we were on our way. All was well as we climbed the well-maintained path beside the River Lair, savouring the beautiful native woodland and warm morning sunshine. By the time we reached the steep pull on to Beinn Liath Mhor's east top, however, pleasantly warm had become uncomfortably hot. It was also really humid and our progress along the bouldery ridge leading to the main summit was slow.

We reached the large cairn topping the Munro at 1:30pm and paused to eat our lunch. Our break was not a pleasant one. We were plagued by swarms of midges and other flying insects and there wasn't much of a view to distract us. It was so hazy that even the neighbouring peaks of Fuar Tholl, Sgorr Ruadh and Sgorr nan Lochan Uaine were barely discernible. And the temperature at the top was 20C...

After half an hour or so we resumed our walk and within minutes a strange mist started forming all around. I cursed our luck as I dug out my compass, aware that the section between us and the col was a complex mix of crags and knolls. I felt sure that the localised bank of mist in which we now found ourselves would evaporate behind us as soon as we got to Sgorr Ruadh - except that this was no localised mist bank. It thickened steadily, and by the time we'd groped our way down to the col it was distinctly dark and murky. It somehow didn't seem right to continue with the planned route from there, but thoughts of quitting were quickly dispelled. "It could be worse," we thought. "At least it's not raining."

Slogging up Sgorr Ruadh, the feeling of unease intensified and our regular hill chat was replaced with bursts of false cheery banter. On the narrow summit ridge the air became extremely stuffy and the gloom surrounding us developed a dirty yellow hue. Walking a few metres in front of Rita I began to sense that the cairn was imminent. Just then I heard a weird humming sound coming from my trekking pole. It lasted for several seconds and then stopped. I immediately recalled having heard about ice axes doing the same when there was electricity in the air, and realised that we were now in a highly dangerous situation. The wider, potentially safer, east flank of the mountain was probably only minutes away, but there was the small matter of crossing the sharp summit first. I didn't say anything to Rita and we moved on upwards.

Moments later the humming started again. This time, though, it wasn't followed by silence. There was a sudden massive flash and I felt a sharp pain on the back of my head and a heavy thump on the rubber handle of my trekking pole. This was accompanied by a deafening rumble of thunder and the onset of torrential rain. Amazingly, despite the "shock", I seemed OK - but all thoughts of crossing the summit were forgotten as we fled back down the ridge. As soon as we were able to, we quit the crest and descended a short way on to the bouldery side-slope. We then squatted on rucksacks in an attempt to insulate ourselves from the ground while defying our instincts to keep running. This was undoubtedly the worst bit of all, just sitting there feeling utterly helpless and vulnerable as the electrical onslaught raged around us. Eventually, the gap between flashes and rumbles grew to three seconds, so we made our way back to the crest to resume our descent. Lower down the hillside a further bout of rucksack-sitting was required before we could complete our escape to Achnashellach.

Wet, knackered and shaken, we headed for the nearest bar, the Ledgowan Lodge at Achnasheen. As we downed a much-needed pint, the proprietor told us the storm was the worst she'd seen in her 32 years there. It certainly was unlike any I'd experienced previously. There had been no front moving in, no build-up of cumulus clouds, just a growing feeling of menace as the thing manifested itself out of nothing.

Healthwise, I got off very lightly. A couple of heavy nose-bleeds over the next few days, bruising on the hand that had been holding the pole, and a circular "exit wound" on my opposite elbow. I also developed strange lines running along the tops of my shoulders. An ECG scan revealed that my heart was OK, and the comments about how lucky I'd been came in thick and fast. The psychological effects took a few years to subside, however. I became an avid sky-watcher, monitoring clouds intently as they grew, shrunk or simply drifted by. Walks were even aborted on several occasions. I remember quitting the high ground early during a backpacking trip round Loch Mullardoch in May the following year. This was just because it had gone a bit grey after two days of perfect weather. A few weeks later, in Glen Taitneach, I retreated from the approach to Carn an Righ due to the briefest hail shower on an otherwise sunny day.

Nowadays my fears have subsided considerably, though I still maintain a healthy respect for unusual weather. I've often heard the claim that due to global warming we can expect more stormy weather in the Scottish Highlands in the summers to come. If this is the case, then there should be more discussion on the subject of mountain thunderstorms. At the moment it takes a tragedy such as the fatality on Ben Oss to bring the topic briefly to the fore, and the advice given on what to do if caught out can be patchy and inconsistent. Personally, the point about which I remain unsure is what to do with my trekking pole when things get decidedly murky. Listen to it and pray that it stays silent - or throw the damn thing over the nearest crag?

Lindsay Munro

THE BASE OF A thunder cloud is negatively charged. On the ground beneath, positive charges are drawn into the "footprint" area beneath the cloud - and the narrower the gap between ground and cloud, the more positive is the induced charge. Once the electrical potential gradient reaches around a million volts per metre, the insulating properties of the intervening air break down and - ka-BLAAAAM! - lightning crosses the gap. Since lightning can travel horizontally as well as vertically, strikes both precede the rain and trail behind it.

Charges can cluster more densely on convex objects than on flat or concave things - so the spikes on ice axes and walking poles are pretty good at building up a lightning-friendly charge; but the human head is marginally better. Conductive channels are always welcome to a lightning bolt, so metal poles and axes may marginally increase the likelihood of a strike - but remember that this stuff has already blasted its way through hundreds of metres of air, so it's not going to fret greatly about the precise conductive properties of the last couple of metres to the ground. Once you've been struck, it's even possible that a well-planted pole might save your life, offering a low-resistance pathway to earth that bypasses your heart - but that's probably not something you should rely on. Don't rely, either, on your rubber-soled boots: Big Electricity, of the kind that comes looking for you across a kilometre-wide spark gap, will laugh at a couple of centimetres of rubber. This is stuff that, when it hits a car, simply blows out all four tyres on its way to the road.

When lightning hits the ground, current flows through the earth in a wide area around the point of impact. This is how a lightning strike can kill a field full of cows - the long wheelbase of the average cow means that a nearby strike induces a significant potential difference across the ground spanned by the cow's front and back legs; current flows through cow, cow dies.

From all this, it's easy enough to deduce some rules to maximise your survival chances if you're caught out:

Never continue upwards after warning signs (thunder, hair standing on end, humming metalwork).

Remove metal items, especially if they're pointy and sticking up off the back of your pack. Place them on the ground and move away from them.

Don't lie down flat - although it gets you as low as possible, it exposes you to a bigger ground voltage from a nearby strike. (Remember the cows.)

Instead, crouch with your feet together and your head tucked down. Sitting on something relatively non-conductive (a rucksack, a coil of rope) is OK, but don't support yourself with your hands, as this spreads your area of ground contact. (Those cows again.)

Don't shelter under or near tall objects such as trees or cliff-faces - they're more likely to be struck by lightning, and you'll become incorporated into the current path. In particular, avoid cave-mouths and overhangs, which accumulate charge along their convex rims and may receive direct strikes.

If you're in a group, spread out and crouch separately - if one person is hit, the others will be uninjured and able to give immediate aid.

Don't be in a hurry to stand up again - let the storm pass over.

And if the worst happens: it's always safe and well worthwhile to attempt immediate CPR on a lightning casualty. Some victims suffer a period of paralysis and need no more than a bit of mouth-to-mouth to keep them alive until they can breathe for themselves again.

Grant Hutchison

image from The Angry Corrie

Ed. - The Ben Oss fatality prompted the publication of an extraordinary piece of bad advice attributed to Alfie Ingram, leader of the Tayside Mountain Rescue Team. In the course of its front page report on 11 May, the Courier included this: "Mr Ingram recommended that any climber who fears a lightning strike should lie down on the ground, or seek shelter such as an overhanging rock." One has to presume that this does amount to Ingram's understanding of what to do in such a situation, even though he added some more sensible/normal guidelines and even though the passage didn't appear as a direct from-his-lips quote. Two days later the paper published a well-written rebuttal letter ("I am extremely concerned..." etc) from a chap in Perth, but it's worth reiterating here that Ingram's advice is unequivocally dangerous. It increases risk to lie down if caught in a lightning storm, and it increases risk to shelter under an overhang.

We seem to be in a phase of Startlingly Bad Advice appearing in print. Ingram's guidelines wouldn't necessarily lead to the certain death suggested by Trail's Ben Nevis descent route (see TAC61, p2), ie there's a chance that a walker doing what he suggests might get away with it. But, as recommendations go, this one isn't exactly conducive to longevity.

TAC 62 Index