Lightning

Lightning: A Field Guide

Recommended Equipment 

-          Something non-conductive to squat upon (eg. bedroll)

Operational guidelines - General: 

The principles for thinking about lightning are: 

-          Minimise exposure in the first place (eg. don't be on an exposed ridge during a storm, plan to finish activities before a storm is due, etc) 

-          Lightning takes the path of least resistance (don't be that path for the lightning)  

-          Understand the ball of lightning principle. (Roll an imaginary 60-meter sphere across the landscape and look at where it touches. Places that the sphere makes contact with - treetops, fence posts, and golfers - are potential lightning targets. Make sure the ball touches something else first) 

-          Minimise damage to everyone in your group (get people to put their feet together, squat and sit on packs/mats, etc) 

-          Minimise losses (if possible, spread out – that way if lightning does strike only one person gets hit, not everyone) 

Other recommended practices: 

-          Putting your feet together significantly reduces the effects of ground current which causes about 50% of all lightning fatalities 

-          Flash to Bang interval: count the delay between seeing a lightning flash, to hearing thunder. Every 3 seconds of delay between a flash to thunder, roughly equates to a distance of 1 kilometre.  You should seek a safe location whenever the Flash to Bang interval is less than 30 seconds (10 km) distance. 

-          Spread the group out (5 to 10m between people). 

-          As a solo group leader, it is recommended to give emergency communications devices (eg mobile phone or PLB), and instructions for how to use them, to someone who is not you. That way if you are struck, someone else can call for help. 

-          With 2 or more leaders, you should take half the group each and spread out so that both leaders are not injured in the event of a strike. There should be more than 60 metres between the two parties (ideally more than 100 metres).  

-          If your hair stands on end and/or hear ‘crackling noises’, lightning is about to strike! Assume a crouched position with your feet together (or sit with your feet tucked in close to your body) and head down with your hands on your knees. 

You should avoid: 

-          high, exposed ridges (descend to a lower elevation and seek a depression in the landscape) 

-          bare/exposed rock (especially ironstone) 

-          small caves and overhangs (Rock shelters, cave entrances, rock cracks or seams and overhangs are especially hazardous because lightning travels along vertical surfaces to reach the ground. When lightning needs to jump the gap, any object bridging the gap can help conduct the current.) 

-          solitary trees 

-          water (puddles, or any larger body of water) (Water is conductive and your head poking up is the highest point on a large flat surface. If lightning strikes water, the electricity spreads outward, mostly over the surface.) 

-          conductive equipment or infrastructure (eg. large amounts of climbing hardware: carabiners, descenders, ascenders, metal pack frames, etc. But also wet ropes, fences, handrails, lookouts, metal stairs, bridges).  

Some background information: 

-          More info on the ball of lightning principle: https://what-if.xkcd.com/16/  (here is a great video showing how it looks: https://www.youtube.com/watch?v=4q6gHWN8fDE ) 

-          Some other useful Q and A about lightning: http://www.pbs.org/wgbh/nova/earth/dwyer-lightning.html 

-          Lightning can travel many kilometres through the air, beyond the range of thunder, to locations where there is blue sky overhead. It is possible to be outside, not hear any thunder or see any clouds, and still be struck by lightning.  

-          Lightning strikes involving people: 10% result in deaths, 90% result in injuries.  

-          There are 5 to 10 deaths from lightning per year in Australia. 

-          About 80% of survivors have serious long-term disabilities. 

How lightning injures and kills 

-          Direct strike - statistics show that death resulted in over 70 % of cases.  

-          Side flash/splash - e.g. standing near a tree - this can be as serious as a direct strike.  

-          Contact potential - physical contact with struck object has similar consequences to direct strike. (eg. leaning on a fence)  

-          Ground Strike/Step voltage - lightning impulse traveling through/on ground and may pass through one limb/part and out another. Injuries include burns and paralysis but these are usually temporary.  

-          Surge propagation - person close to or in contact with an electrical appliance or power /communication line. Serious injury and death is not common.  

-          Blast Effect - Lightning victims are sometimes thrown violently against an object, or are hit by flying fragments (e.g., a shattered tree), so first aid may have to include treatment for traumatic injury.