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Mountains of Pressure

Yesterday's walk was my middling size route, about 2½ miles. Still speeding up a bit, although the bitter cold caused by a strong wind may have provided the incentive for an even brisker walk than usual.

My weatherman pal, Seán Batty, reports that the barometric pressure at his home is at the highest he has ever seen it, 1,049 hectopascals, in old money 1,049 millibars, or in very, very old money, 31 column inches of mercury.

Part of Scotland's heritage is our hills. In particular the "Munro"s. Those hills over 3,000 feet high. There are also "Corberts" which are the ones over 2,500 feet but I don't think I've heard walking pals talk much about these tiddlers. But then it's not the height that's really the challenge. It's our very changeable weather.

In 1965 (I think), I was with a group of pals on a walk from the Cairngorm ski lift car park, up over the top to Beinn Macduibh. That's Scotland's second-highest hill. And back.

It was Easter weekend and the hills were fair buzzing with activity. The sky was absolutely clear without even a single cloud. There was what I might term a reverse wind-chill factor in operation.

The sun was being reflected off the snow and it was fair warm. Not long after crossing by the top of Cairngorm, we are striding across the plateau wearing nothing more than shorts, socks and boots, well-equipped backpacks. Holding in our hands, of course, the maps and compasses that are essential safety items on our hills.

The backpacks contained a couple of small tents, emergency rations - cooked porridge, Mars bars, chewing gum, water, foil sacks for insulation if caught on the hill, crampons, gloves, balaclavas and ice axes.

The modern idiot's total equipment list nowadays seems to consist solely of the mobile phone to call out the mountain rescue team. Supplemented by a lack of understanding that that phone won't work out there much of the time because there's no signal. And in cold weather, the battery's capacity can drop alarmingly.

I remember once coming off the lower slopes of Sgùrr nan Gillean, on Skye, to find the Invernesshire Constabulary Mountain Rescue team milling around in preparation for returning to the hill to search for two of their number who had not returned on time from a training mission.

We were on the brink of being seconded to assist when they appeared out of the mist. Thank goodness. I am not sure we would have up to the job. Actually, I know we weren't.

Even the best-equipped can be caught out on our hills.

Unequipped idiots have only one skill. That of turning a risk into an inevitability.

Our stroll across the Cairngorm tops went well, not all of us chose to make the final climb up Macduibh. We, I was among this group, lingered in the beguiling warmth at its foot.

The way back would have involved simply stepping into the footsteps of our outward journey but for one thing. It may have been bright, but boy, was it actually cold at foot level. There really no footsteps imprinted on the surface to follow back. Maps, Maps, and compasses, essential.

The snow, our six-foot poles did not bottom out when we tried to measure its depth, was frozen solid at the surface but retained enough grip for us to walk merely in our boots.

As one of the less experienced in the group, it may seem odd that I was leading the group back. But I was. The visibility was forever. And in a couple of hours, we could see, and hear, in the distance, people in the car park.

Quite suddenly a small black cloud appeared on the horizon. And rapidly headed our way. We stopped and re-clothed ourselves against the reducing sunlight that had been warming our epidermis.

And almost immediately we were in no more than 10 feet visibility as we were engulfed by heavy falling snow.

It was at this point, as my companions later described it, I simply disappeared. Silently and suddenly.

I knew where I was, of course. Rapidly accelerating as I fell through the snow cornice that had been overhanging the edge of the corrie around whose edge we had been walking. A few feet of course deviation in that reduced visibility had me walking onto unsupported snow and ice which, as I now knew, could not support my weight.

To this day I always report this as a 300-foot drop. The reality is I have never been back to measure it. But it sure was far enough for me to be travelling downwards at a significant speed when I made contact with the ground. Terminal velocity for a human who falls face down and with legs and arms spread wide, parachutists calls this the "stable position", reaches 120 miles per hour in about 4 seconds.

My fall felt like a lifetime, so I may have broken the sound barrier. No. The limit is a mere 120mph.

The first, and fortunately last, contact with the ground was at a very narrow angle-of-attack. So I started, entirely inadvertently, a slide down the face of the corrie.

The correct procedure for all this is to grip one's ice axe with both hands. Dig the point of the axe into the snow and ice. This enables one to start to slow down and gives one some ability to steer away from dangerous obstacles.

The only problem was I had no ice axe in my hands. But I was holding a small geological hammer and I used that. Less effective but good enough.

With hindsight, it might have also been useful to be wearing gloves. As my bare hand was clasped tightly, very tightly, around the shaft of the hammer, the knuckles were in intimate contact with the hillside of snow and ice as I slid down.

When I reached the bottom, I stood up, a bit sore but with no obvious bones broken. No fountains of blood either. But a close examination of my knuckles gave me my first real-time view of what an anatomical dissection must look like. Tendons and bone were exposed to view where the hill had scraped many layers of skin off.

The black cloud had disappeared when I looked up. And half an hour later, I rendezvoused with my pals in the car park. They hadn't been much worried. They'd been able to hear my cursing as I resumed my walk so they knew I was still with them, even if 300 feet away.

As Seán Batty wasn't born until 1982, that black cloud couldn't have been his fault, could it?

But he owns our hectopascals, yesterday, all 1,049 of them. And they play a very important part in the history of our hills, especially our "Munro"s.

For every 30 feet we climb upwards, we lose one hectopascal. That allows a mountaineer who carries a barometer to measure the altitude of a hill. Provided they know the pressure at sea level nearby. Count the lost hectopascals, multiply by 30 and, bingo, you have the height.

And that's how the first measurements of our hills were made.

My daily walk can take me about 170 feet up. But now it's a satnav that measures that for me. And accuracy in the modern age is much greater than in the days of measuring by pressure. In recent years, two "Munro"s were demoted as it was found that they were 2 inches and 4 inches respectively below that magic, if totally arbitrary, 3,000 foot.

Thanks for lending us your hectopascals Seán.


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