Salut mes amis,

Had a sobering experience at the weekend in the mountains. Sunday morning, on a sharp summit of a mere 2400metres in height but isolated by alpine standards some light cloud started to build up, didnt look threatening, I'd been in these conditions hundreds of time before, often they give the best moodiest mountain photos. The cloud rose into the summit, 20mins later a light precip. No point in hanging around may as well start on my way down a now slippy, steep, fairly sharp ridge, descend off the ridge about 20 or 30 metres for security, still well above 2000metres when I alomost get knocked off my feet,but luckily back in towards the rock, I grab onto the solid limestone and try to compose myself. It took me only a millisecond to realise what had happened. It felt like someone had just punched me in the chest and ripped off my ears. I knew I'd just been hit by some sort of pressure wave. Rock fall rumbles through the cloud and some small rocks fall from above and pass my feet. I start to slide down the rock almost uncontrollably using hands and feet, trying to get out of there in panic knowing I must now be in the middle of an electrical storm - not forecast, not foreseen and misjudged by me. 2 mins later, a huge clap of thunder bounces off the mountain walls, much louder than Im used to hearing but at least I heard it this time. One flash of lightening 1 min after and that was it, it rained but no more electricity in the air.

My question is, and I cant seem to find the answer myself, just how close are we to lightening if we get hit by a pressure wave? I didnt even see a flash but then I dont remember hearing a sound either, the impression of an impact on my body like someone had just punched me hard with both hands in the chest was disturbing, and it was only blind luck that i lost my balance falling into the slope. So I'm scratching my head wondering just how lucky an escape that was, just to make it even luckier, I did have a piolet in my hand and two trekking poles strapped onto my bag so ony by blind luck i dodged a bullet. Would anyone know by how much? If it was THAT close how did I get away with it? Or even if there is an alternative explanation, a top secret silent sound barrier breaking aircraft doing a flyby for example!?

Sound doesn't necessarily travel in straight lines from the source in all directions, it can refract according to atmospheric density contrasts, much as a seismic wave will bounce around between layers in the ground.

On the other hand a pressure wave at sub-audible frequencies and/or short enough in duration for your brain not to register it may appear to be a pulse that you feel but not hear.

Ever gotten a strong electrical shock? You don't necessarily feel it until after it's over, but your muscles can contract suddenly, and you may not have any memory of the actual moment you got zapped - you just find yourself falling over and it takes a few seconds to connect it to that dangling wire...

I'm wondering if you experienced a ground current. The lightning strike was probably above you and/or on the other side of the pinnacle; it would all happen so fast that you might not notice any flash or thunder (there's no delay before the thunder if the lightning is right next to you).

In the end, it's all been pre-determined by the Grim Reaper ..

http://www.summitpost.org/thunder-lightning-in-memory-of-a-friend/422948

Having been shocked (not hit directly) with lightning twice (1987 and 1991), I would say that you can definately feel and sometimes smell the electricity if you were close to being struck. All your hairs will be standing on end and you can easily feel the charge. There is no question about the feeling. The first time we could smell something that smelled like molton metal as well.

[youtube]http://www.youtube.com/watch?v=Tpy_pYXSpPA[/youtube]

Thanks for the feedback guys. Unfortunately i can't access Mr Burds site from my country.

Scott, your experience makes me feel like i haven't used up as much of my luck as I was thinking, thanks.

I've experienced the hairs standing plenty of times, even had singing piolet a couple of times. No singing piolet or hairs standing on end this time, but hairs standing on end during the second and third strike. I've also had electric shocks before so I didn't equate what I felt to any kind of electrical shock, though if it was that close, on fairly solid limestone I guess its possible. Could a shock from a difused current through the feet feel like an impact? In anycase, I've had to re-evaluate just what constitutes dangerous weather, I've been consistantly in the mountains for 7 years now and have never had to question my judgement on atmospheric condistions before, but hey, thats the mountains, a cruel and unpredictable mistress.