Lightning Safety
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 firewood) – the smell, the sound of thunder and nature’s pyrotechnic display are 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 should be taken. It should also be noted that our high incidence of lightning fatalities is not only due to people being outdoors, but also 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 increase the risk of being struck – read on to find out why and what’s best to do.
A brief intro on how lightning works
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 lightning. Cloud-to-earth lightning (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 kinds of strikes we get are:
- A direct hit
- Ground current – current runs along the ground from a nearby hit (happens with every ground strike). Most lightning strikes on humans are due to ground current, not direct hits.
- Side flash – lightning “jumps” from a nearby tall object.
- Contact voltage – due to touching conductive material when it is struck by lightning.
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 large enough to overcome atmospheric insulation, initiating an electric current. The charge from the cloud “searches” for the most efficient path down, branching through the air (called a “stepped leader”). A positively charged ground point or object sends 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, while the flow from below completes the most efficient route – resulting in a massive upward current through a single channel at a rapid rate. This superheats the channel, creating the bright flash of 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.
https://www.youtube.com/watch?v=dukkO7c2eUE
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, it’s a rough guide at best. The clearest indicator is the development of cumulonimbus thunderheads, which conglomerate to form thunderstorms. On many occasions, I have been surprised at how storms seemingly developed out of nowhere, as the clouds formed behind a hill or out of sight. If you can, stay clear.
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 indoors – and with “indoors” here I mean within a proper building with earthing (plumbing and electricity), not a shack, tent or gazebo. Interestingly, cars are safe not because of rubber tyres, but because the metal body is an excellent conductor of electricity – the charge runs over the bodywork on the outside, leaving passengers safe.
Where lightning strikes
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 least likely to strike. The order of danger is determined by:
- Relative height (summit vs. valley)
- Isolation (e.g., tall tree in an open field)
- Streamlined, skinnier shapes (tree or antenna vs. boulder)
Water deserves special mention: though often lower lying, it presents more danger due to its conductivity.
An excellent diagram showing the relative safety of various outdoor locations. Water and lone trees belong in the “most danger” category. (Source: Climbing.com)
Your best option is to find an area low relative to the surrounds, or an area with uniform mid- to low-height trees or shrubs. Stay clear of peaks, ridges, lone trees, or cave entrances. The latter may surprise you, but if lightning strikes near the cave, the electrical current can travel through the ground. Standing at the cave entrance can make your body the path between the lip and the ground below. If you shelter in a cave, stay at the back, clear of the roof and walls, and avoid shallow overhangs altogether unless there’s no better option. 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 under clear skies. Thunderstorms can develop overnight and surprise you in the early hours.
Lightning position
I have on occasion seen people dive to the ground, with a 25 kg backpack on, as lightning flashed in the clouds that enveloped us. It’s a bad idea for several reasons:
- Diving after the flash is too late; lightning has already struck.
- Diving with a backpack can cause back or other injuries.
- Being flat on the ground is one of the worst positions since the ground current from a nearby strike will run through your entire body.
If you’re stuck in a lightning storm and have found the safest location available, 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 with the ground, keeping your feet together and arms tucked in. Your low profile reduces the risk of a direct hit, and limiting your contact with the ground reduces the current that could flow through you. Don’t touch wet or metal surfaces. If you’re in a group, stay 15–30 m apart to avoid multiple injuries from a single strike.
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 on end (static electricity), crackling sounds, skin tingling, light metal objects vibrating. At this stage, there’s little you can do to avoid being hit – most experts recommend getting into the lightning position, covering your ears (to protect eardrums) and holding your breath (to protect lungs from shock wave).
Lightning struck – what now?
The good news: 90% of lightning strike victims survive. The bad news: 70–80% of survivors suffer serious, sometimes permanent injuries. Most fatalities result from cardiac arrest. If someone is struck by lightning, follow this protocol:
- Immediately check for pulse and breathing (it’s safe to touch them)
- If there’s no pulse or breathing, perform CPR – focus on chest compressions
- Seek medical assistance immediately
Lightning mythbusters
Myth: Under clear skies, you’re safe from a strike.
Busted: “Bolts from the blue” can strike as far as 30 km from storm clouds. If you can hear thunder, you’re within range.
Myth: Rubber tyres or shoes insulate you from lightning.
Busted: The amount of rubber is far too small to insulate from lightning’s voltage.
Myth: Having metal in your backpack increases strike risk.
Busted: Non-protruding metal does not attract lightning. Only objects extending upwards increase risk.
US statistics on what victims were doing when struck by lightning:
- Fishing – 25%
- Camping – 24%
- Swimming – 18%
- Hiking – 7%