Yesterday I reached the summit of a 4000m while a thunder cloud was passing on it (not over it). My hair eventually got straight in the air and I could hear the wet rock making that characteristic drizzling sound like the one you hear under power lines during rain.
After reading about similar experiences, I realized that apparently no accident ever happen in such circumstances just like for me. Knowing a bit about electricity I started thinking that being on the ground but high enough so that you are actually inside the charged cloud itself, is it more dangerous or in fact LESS dangerous since you stand in the middle of these electrically charged droplets.
My hair pointing upward and the drizzling sound may just in fact reveal the difference in charge between myself touching the ground and some droplets above me. But is that potential really more dangerous than those shows where the magician has the hair of a little girl gettiing straight in the air?
So what is really happenning when a thunder cloud touches a mountain?
It’s actually very dangerous to be on an exposed mountain top when a lightning storm is around. People can get hit, and get killed. You were lucky, but not wise to stay there without seeking shelter. Being over or in it doesn’t make a significant difference. If there is lightning around it may take a path through you.
Cloud to ground lightning is the third most common type with cloud to cloud and intracloud being several times more common. I don’t know if the mountain changes the dynamic but being in the middle of the cloud theoretically puts you in the middle of all of it.
Lightning occurs when the electrical potential difference between cloud & planet is large enough to jump the air gap between them.
When an active thunderstorm drifts over a mountain, all else equal you will see more frequent but less intense lightning as the air gap becomes smaller.
The “top” of a lightning bolt is pretty close to the top of a thunderstorm. Which is vastly taller than any mountain people routinely hike up and down (i.e. ignoring Everest, etc.). So the difference in air gap distance is more like 1/3rd to 2/3rds normal, not way down at 5% - 10% of normal.
With the result that even the reduced lightning intensity is still waaay up in the lethal range while the frequency is up by 2 or 3x. Couple that with being near the high point of an otherwise barren mountain-sized lightning attractor, and hiking near the summit of a peak in/near a thunderstorm becomes a very hazardous activity indeed.
The good news is that if your luck runs out it’s unlikely to hurt for long.
Its not the lightening that’s the danger - its the weather.
When you consider what causes the friction which generates a charge, what you have may well include very heavy up draughts, possibly getting toward localised hurricane force, large hailstones, extremely heavy rain.
Any one of these would make life in a mountainside pretty dangerous, combine them and add in lightening, oh, and add in the chances of landslip, huge water flows and avalanche, being up a mountain during a thunderstorm has the potential to be very risky indeed