Lightning safety

lightning-safety-afternoon-thunderstorm
Late afternoon lightning storm. (Photo: wildbackpacker.com)

Living in the Western Cape has its perks, but I really do miss the thunderstorms of my home turf in the Waterberg (along with thorn trees and proper fire wood) – the smell, the sound of thunder and nature’s pyrotechnic display is awe-inspiring.  Thunderstorms, however, are a real danger to hikers and other people who love the great outdoors.  South Africa has one of the highest lightning-death rates in the world, with the latest government estimate being 6,3 per million annually. However, fatalities from lightning strikes can be reduced significantly by understanding how lightning works and what safety precautions are to be taken. It should also be noted that our high incidence of lightning fatalities is not only due to people being outdoors, but to a large degree due to people living in structures that are not lightning proof.

I have been hiking in the Drakensberg for many years, and have thus experienced many thunderstorms. What struck me (excuse the pun) when doing the research for this article is how often I placed myself in more danger, thinking I was making my situation safer! Seemingly logical responses, such as lying flat on the ground or finding shelter under a rocky overhang actually increases the risk of being struck – read on to find out why and what’s best to do.

A brief intro on how lightning works

lightning-safety-cape-town-thunderstorm
A rare and spectacular lightning display over Cape Town. (Photo: Jason Hayden)

We get two kinds of lightning: cloud-to-cloud and cloud-to-earth lighting. Cloud-to-earth lighting (aka a “ground strike”) is the real danger. It may surprise you to know that a lightning strike is not only from above, but also from below – and the current from below is the stronger one! The kind of strikes we get are:

  • A direct hit
  • Ground current – the current runs along the ground from a nearby hit (happens with every ground strike). Most lightning strikes on humans are not direct, but due to a ground current.
  • Side flash – lightning “jumps” from a nearby (tall) object.
  • Contact voltage – due to touching conductive material when it is struck by lightning

This is how ground strikes work (in oversimplified terms):

Thunderclouds develop a negative charge due to the movement and friction of tiny particles in the cloud. Ground strikes occur when the difference in electrical charge between the earth and a thundercloud is sufficiently large enough to overcome the atmospheric insulation, and initiate an electric current. The charge from the cloud “searches” for the most efficient way down, branching through the air (called a “stepped leader”). A positively charged ground point or object will send a “spark” that connects to the stepped leader, completing the path from below via which the charge will flow. Hence, the flow from above is searching and branching out, whilst the flow from below completes the most efficient route – resulting in a massive flow of upward current through a single channel at a rapid rate. This super-heats the channel, giving the bright flash which we refer to as a lightning strike, while the rapid expansion of heated air causes thunder.

The super-slow-motion video below shows the split-second formation of a ground strike. See how much brighter and stronger the “ground up” flash is.

Anticipating thunderstorms

A thunderstorm is the mothership of lightning strikes, and hence your first step for safety is to avoid them or find a safe place before it reaches you. Thunderstorms develop mostly in the South African interior, and are typically a late-afternoon phenomenon in summer. The weather forecast is the first indicator, but because storms are often quite localised, the weather forecast is a rough indicator at best. The clearest indicator is the development of cumulus nimbus thunderheads, which conglomerate to form thunderstorms. On many occasions, I have been surprised at how storms seemingly developed out of nowhere, as the clouds conglomerate behind a hill or out of sight. If you can, stay clear.

lightning-safety-cumulus-nimbus
A sure sign of a local thunderstorm: cumulus nimbus thunderheads start to conglomerate in the Mapungubwe nature reserve. (Photo: Andy Nix – pix.andynix.co.za)

Lightning proof

The only way to be completely safe near a thunderstorm is by being in a car or being indoors – and with indoors here I mean within a proper building with earthing (plumbing & electricity) – not a shack, tent or gazebo. Interestingly, the reason why cars are safe is not because of rubber tyres. The vehicle’s metal body is an excellent conductor of the electrical charge, hence it runs over the body work on the outside, leaving the passengers safe. [See the important video at the bottom of the page]

Where lightning strikes

lightning-safety-waterval-boven
Hurrying to reach safer ground as a thunderstorm approaches the escarpment near Waterval Boven. (Photo: Gustav Janse van Rensburg)

If being in a car or indoors is not an option, the second step in staying un-sizzled is to find a spot nearby where lightning is the least likely to strike. The lightning strike order of danger is:

  • relative height (summit vs. valley),
  • isolation (think tall tree in an open field),
  • streamlined, skinnier shape (tree or antenna vs. a boulder)

Water gets a special mention since its generally low lying relative to the surrounds, but presents more danger due to its conductivity.

lightning-safety-diagram
An excellent diagram that shows the relative safety of various outdoor locations. What can be added to the “most danger” category is water (puddles, pools, dams, streams) and lone trees. (Picture from Climbing.com)

Your best option is to find an area that’s low relative to the surrounds, or find an area of uniform mid to low height trees or shrubs. Stay clear of peaks or localised rises/ridges, lone trees or cave entrances. The latter may surprise you, but the logic holds: if lightning strikes the area close to the cave, the electrical current will run through the ground along the most conductive path. If you stand in the cave entrance, your body becomes that path between the cave’s lip and the ground below – if you do shelter in a cave, try to be at the back but stay clear of the roof or walls, and avoid shallow caves/overhangs altogether unless there is no better position available. The same holds for hiding under concave rocks.

If you’re camping in a thunderstorm prone area like the Drakensberg, pitch your tent in the safest location even if there’s clear skies. Thunderstorms develop overnight and you may get a surprise storm in the mid-night hours.

Lightning position

I have on occasion seen people dive to the ground, with a 25kg backpack on, as lightning flashed in the cloud that enveloped us. It’s a bad idea for several reasons:

  1. Diving after the flash is too late; lightning has already struck.
  2. Diving with a backpack can result in back and other injuries.
  3. Being flat on the ground is one of the worst positions to be in since the ground current of a nearby strike will run through your entire body [see important video at the bottom].

If you’re stuck in a lightning storm and have found the safest location in the landscape, you need to wait it out. If you’re very exposed, or detect an imminent strike, get into the lightning position: squat down, with your feet being the only contact to the ground, keeping your feet together and arms tucked in. Your low profile reduces the risk of a direct hit, and limiting your contact surface with the earth reduces the ground current that could flow through you. Minimising contact surface also means not touching conductive surfaces – the electrical current travels well over wet and metal objects, so find the driest surface and don’t hold onto a fence or waterpipe. If you’re in a group, stay about 15m to 30m apart to avoid having more than one person struck simultaneously.

lightning-safety-position
Assume the lightning position when caught in a thunderstorm in an exposed position. (Source: outdoors.stackexchange.com)

IMPORTANT! Signs of imminent lightning strike: hair standing up (static electricity), cracking/static sounds from the air, skin tingling, light metal objects vibrating. At this stage, there’s not much you can do to avoid being hit – there’s a small chance that running for better cover will work; most experts recommend getting into the lightning position and cover your ears (protect eardrums against shock wave) and hold your breath (superheated air will damage your lungs).

Lightning struck – what now? 

The good news is that 90% of strike victims survive; the bad news is that 70% to 80% of those have serious injuries resulting in permanent disability. The fatalities are mostly due to cardiac arrest. If someone is struck by lightning, follow this protocol:

  • Immediately check for pulse and breathing (don’t worry, lightning does not linger – you can touch them)
  • If the victim is in cardiac/respiratory arrest, proceed with CPR and focus on the heart compressions more than assisted breathing
  • Find medical assistance ASAP

Lightning mythbusters

Lastly, some lightning mythbusters and stats:

Myth: Under clear skies, you’re safe from a strike.
Busted: “Bolts from the blue” can travel and strike as far as 30 kilometres from storm clouds.
You’re within strike range if you can hear thunder. Look for shelter when a storm approaches.

Myth: Rubber tires or shoes insulate you from lightning
Busted: The amount of rubber in these items is way too small to insulate from the incredibly high voltage of lightning.

Myth: Having metal in your backpack (phone, cookware etc.) increases the chances of being struck.
Busted: There’s no evidence to attest to this unless the metal protrudes up in the air. Metal is a very good conductor of the current and hence can give the most efficient path, but non-protruding metal objects do not “attract” a lightning bolt.

US-statistics on what victims were doing when lightning struck them:

  • Fishing – 25%
  • Camping – 24%
  • Swimming -18%
  • Hiking – 7%

Very important safety video:

Resources:

  • Wikipedia
  • com
  • com
  • com
  • stackexchange.com
mm
About Willem Boshoff 17 Articles
Willem is an actuary by profession and an adventurer at heart. He spends as much time as possible outdoors - camping, hiking, mountain biking, surfing and rock climbing are his activities of choice – and he enjoys reading and writing. He has hiked and trekked in the Himalayas, Andes, Patagonia, Alps, Corsica and done the Camino Portugues, and thinks locally the Cederberg and Drakensberg offers some of the best wilderness-hiking experiences in the world. He is also passionate about conservation and sustainability. He lives in Cape Town.

4 Comments

  1. I see my photo of the lightning over cape town has been used in this article without permission.. Where did you take it from?

    • HI Jason
      The picture is pretty much all over the interwebs. Would love to engage directly with you on this though, and will of course take it down if you are not happy for us to use it.

  2. Thanks Willem, super informative. Especially the danger of caves and lying on the floor, both tactics I’ve ironically employed to reduce chances of getting hit!

  3. It’s all good and well – but sometimes you are just in the wrong place at the wrong time with little you can do about it. A cave may be more dangerous in a thunderstorm from a lightning strike point of view, but crouching outside in the rain is more dangerous from a hypothermia point of view – and sometimes there is nothing you can do anyway. I have been near lightning strikes a few times, a year ago I was within the blast radius of one – far enough away that it felt like the static shock from a car door, but still enough to be really scary. My accompanying summit shot includes my hair standing straight up!

Leave a Reply

Your email address will not be published.


*