Close encounters of the 300MV kind

Off Topic
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I was just west of the summit of ZL3/WL-318, mid afternoon Monday. Known locally as Ridgeline this summit is the southern peak on the sometimes knife-edge ridgeline between the Lake Greaney basin and the deep depths of the Waiatoto valley, a 1500m stone’s throw to the east.

Weather was light whispy clag, the sun almost visible through the haze, temperatures in the mid 30’s on the coastal plain 1500m below, and still hot and humid even at this altitude. I stopped for no more than 2 minutes, stowing tools in my pack and taking a much needed swig of water.

When I looked up the bright hazy day had turned black. Goosebumps were already prickling on my sweat-soaked skin as the temperature plummited. I grabbed my pack and proceeded to get outa there! No easy task on a knife-edge ridgeline where the only safe options were a cautious scramble along the crest.

5 minutes later saw me 250m from the summit and maybe 80m below it, focussed on the tricky descent.When three things happenned in rapid succession.

  1. Someone punched me. Simultaneously, over the full length of my body.
    I had time to think ‘what the …’
  2. I was aware of an intense flash of light
  3. Maybe a second later the deafening clap of thunder followed.

The lightning appeared to have hit the summit, maybe 300m away.

I spent the next 30 minutes cowering under a seriously inadequate outcrop of rock until the heavens ceased hurling 20mm hailstones at me, and mentally filling in the ‘near miss’ report form.

====

Now, I assume the sensation of being punched was my body forming the secondary winding to the transformer the lightning path had just created the primary of. But does that stand up mathematically, over that distance?

What puzzles me is the sequence of perceived events. In my perception, the punch came first. I had time to question it’s cause before I sensed the flash. This could just be delays in perception, but if so it seems back to front: it’s more usual to see injuries happen and have time to anticipate the pain before it arrives.

Or is there an electrical / physics explanation? A delay between the current flow and the ionisation of gasses that causes the flash.

Answers, musings and digressions appreciated.

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I think I remember reading somwhere that the flash in a lightning strike is the return stroke. So the punch you felt first might have been the initial charge movement along the ground to the point of the strike. I’m sorry I can’t quote all the details, maybe someone else will have detailed scientific explanation.
Glad you got far enough away in time though.
Andy
MM7MOX

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Glad, you’re well, Matt. Even after two days, if you feel your heart misses a beat, see a doctor!
I guess you experienced step potential / step voltage, the reason you should always keep your feet close together near thunderstorms.

Ahoi
Pom

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Mine is, I’m so glad you’re here to write about it!

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I went off searching about lightning strikes and found this which is interesting and may help explain.

I’ve been on a summit (VHF/UHF contesting) when there was a hit on a comms tower (Cyrn-y-Brain GW/NW-043). We’d decided the storms were getting nearer so it was time to pack up and everything was stowed into the cars, probably 10 of us and 7 cars, it was still dry. It took about 45mins to rapidly disassemble and pack away.

The strike took place when everyone was getting into their cars. I remember it as a shrieking noise, a blinding white flash and a noise like a whip crack but very loud. I think I couldn’t see properly for a few seconds from the flash. A scramble for the cars and then the rains started. But there were no more strikes closeby.

The strike had hit the BT Type 8 tower which we were nearby. There was more room to setup and it was further from the BBC VHF tower which has about 20kW on Band II into a fair amount of antenna, so best to be just a few hundred metres further away :wink:

This link shows 2 of the masts on site: mb21 - The Transmission Gallery I was there with Brian G4ZRP (SK) and he was keen on Ornithology so he had binoculars with him. We studied the 4 lightning conductors on the top of the BT tower and it looked Stevie Wonder and Ray Charles had been practising welding on them! Large amounts of blobs of metal and they looked very beat up from previous strikes.

We felt quite safe as we were sure any unexpected strikes would go to the towers which had lightning protection and would be properly earthed. But as the storms got nearer we took the wise decision to leave. You can question the wisdom of staying so long or going in the first place. Well we were convinced the towers afforded us protection and we were younger. It was 30 years ago and whilst the indestructibility beliefs of a teenager / twenty-something man had almost left, I still felt it would be OK to be there.

Almost a Darwinian Award moment. I have a very different view of sparks from the sky after that nearby strike. I like to be a long way away from summits and exposed places nowadays!

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Glad you are able to pose us questions!

I agree with Andy mox and sure Andy fmf’s article will explain it.

Does your rig still work?

73

Alan

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You bring up a very interesting topic…
https://www.weather.gov/safety/lightning-struck

My guess is you were far enough away not to be affected by the ground current mentioned in this linked topic (unless you also felt tingling). The energy in the lightning strike causes the air around it to be heated very rapidly so it expands very rapidly over a wide area. It might have been the very strong force of the air (effectively an explosion) that gave you the all-over-body punch.

In that distressing situation it might be hard to recollect in which order you felt the body blow and saw the flash.

I can’t think how your body-as-transformer secondary windings theory would work. Animals and people in the ground current zone are usually killed by the potential difference between one leg and another causing high currents to flow through the body.

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Glad you got away with it. It certainly makes you feel very small and insignificant to nature.

I experienced a strike somewhat closer, with virtually instantaneous “flash to bang” on GW/NW-050 Gyrn Ddu. I was sat activating in light to moderate cloud cover, when it suddenly went much darker, the wind picked up and then hail started. I was just thinking “I wonder if this is a storm” when… BANG!

No shock feeling, just ringing ears. I went QRT, dropped the 2m antenna flat, then sat still in the recommended position, until at least 20 mins had gone by between hearing thunder. Then initiated a rapid descent.

I’d not heard any thunder beforehand. Lightning was not in the weather forecast. It was winter time (not our peak lightning season - spring and summer). I’d been operating on 2m FM and not heard any “odd” noises (at other times I’ve heard static crashes on HF SSB and they are quite noticeable).

As per G8CPZ
“My guess is you were far enough away not to be affected by the ground current mentioned in this linked topic (unless you also felt tingling).”

I do recall a group of 3 people on an Eryri (Snowdonia) summit getting a much closer strike. They called for mountain rescue reporting they all had “broken legs”. In fact it turned out to be temporary paralysis due to the ground current.

It’s an occupational hazard. The more time in the mountains, the more likely you are to get unlucky. We Activators increase our chances by sitting close to summits, sometimes for extended periods. It’s still remarkably rare to get this close to a strike though, especially if you take note of weather forecasts. I still work on the basis that I’m more likely to die on the drive to and from the mountain, than by being struck by lightning when out walking!

On that cheery note… I’ll sign off :blush:

PS some good simple advice.

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