Lightning

Lightning


For hill walkers the dangers of lightning are obvious, but what action do you take on a hillside?


Lightning 

Lightning



There are some clear and obvious dangers of being out on a hill side when there is lightning around, as the lightning bolts will seek out high points (i.e. you) on the surface, especially if they have metal objects (i.e. stuff you carry).

Know how to call for help! Always leave details of your intended route with someone "back home" and confirm when down safe.

Once you've read this page, please take a trip around the Advice & Info section of the site, or for a whistle stop tour, take a look at the Quick Tips page


Danger

As if you need telling... Lightning could kill you. Checking the weather forecast should ensure that you avoid a day when lightning is likely, as storms in the UK are generally known about in advance. But, sometimes they do happen without warning, so you could be caught out.

A lightning bolt making contact with the ground could carry approx 30,000 amps1 of electrical current. Ok, that's a big number, but to give a comparison to every day life, most household appliances carry electricity at the rate of 13 amps. So in simplistic terms, lightning carries 2,300 times more electricity than the power to your washing machine, and we all know it's not a good idea to be exposed to electricity in the home.


mountain & hill walking safety - weather - lightning

Picture courtesy of kcdsTM via CC 2.0
It's not just a direct strike of lightning that is an issue, as any strike close by can lead to a massive presence of electricity in the surrounding ground. Two walkers were recently caught out in Snowdonia (see news below), and although not receiving a direct strike, the soles of their feet were burned and legs paralised - hopefully temporarily.


Guidance

If you are unfortunate enough to be on the hillside when an electrical storm is close by, you need to take the following precautions:

  • do not sit under a tree, for example, to stay dry. Lightning will strike trees as they are high, and you don't want to be close by!

  • do not seek shelter in a cave or old mine. If lightning strikes the ground above the cave, it will take the shortest route downwards, which will be through the empty air of the cave. If you happen to be taking refuge in the cave, the lightning could take a path through you.

  • place any metal and/or electrical objects away from you; at least 20 metres away. Such items include; mobile phone, GPS unit, watch, ice axe, walking pole, crampons, pans, knife etc. Be mindful that your rucksack - older ones especially - can contain metal. The women can decide for themselves whether they want to keep on an under-wired bra...

mountain safety - hill walking safety - caves in lightning - priests hole cave

This is Priests' Hole Cave on Dove Crag in the Lakes. Great for a shelter, but not when lightning around

  • if possible and safe to do so, descend to lower ground (see 'proximity' below)

  • place any metal and/or electrical objects away from you; at least 20 metres away. Such items include; mobile phone, GPS unit, watch, ice axe, walking pole, crampons, pans, knife etc. Be mindful that your rucksack - older ones especially - can contain metal. The women can decide for themselves whether they want to keep on an under-wired bra...

  • sit on your rucksack (which insulates you from the ground) on the hillside, with feet off the ground too, and wait for the storm to pass

  • if close to a rock outcrop or crag, sit away from it, and on lower ground. If on a ridge, and safe to do so, move down hill from the ridge, as you do not want to be the most prominent object on the ridge (especially flat-ish grassy ridges). If you are close to a pinnacle, the safest place is within an equivalent distance horizontally compared to the height of the pinnacle (also see images in this link). 

  • do not sit close to any standing water, i.e. tarns/lochans/cwms, as it may attract lightning


Proximity

The time between seeing a flash of lightning to hearing the crack of thunder can be used to calculate the distance of the lightning from you. When you see a flash of lightning, count the number of seconds until you hear the thunder, then multiply that by 300, which is the distance in metres between difference in the speed of light and speed of sound. For example, if you count 3 seconds between flash & bang, the lightning is approx 900 metres away.

If the storm is far away but getting closer and you can safely descend to lower ground, you should consider doing just that. If the storm is close, sitting it out - as above - is probably safer than trying to out-run the storm.


News Stories

Links


Sources

1. Wikipedia