Microsoft Encarta link
Via message from Wagionvigil:
One of the links on the Electricity merit badge page points to an encarta article with bad advice for reducing the risk from a lightning strike.
The article advises correctly to:
- Avoid trees
- Take shelter in a car
and incorrectly to:
- Lie flat on the ground
This bad advice is based on the idea that you are less of a target for a direct lightning strike by staying low to the ground. While this is true, there is little to be gained between lying flat and squatting. However, by lying flat you insert your body as a parallel conductor in the any ground surface currents from a nearby lightning strike. Being near a lightning strike is much more likely than being directly hit with lightning.
Because the energy in lightning is so high, typically currents in the ten's of thousands to hundreds of thousands of Amperes are developed. This current largely dissipates across the surface of the earth. Because the currents are so high the potential difference across the dimension of a human body is more than sufficient to develop a lethal current and induce heart failure.
The better advice is to squat on the balls of your feet on an insulated surface such as a life jacket or doubled up sleeping pad. Keep your feet close together and avoid touching the ground with your hands. By squatting, you also reduce the possibility of a direct strike without increasing your risk from a nearby strike.
If you are in a group, spread out so that risks from a very near strike are minimized, and the possibility of survivors being able to assist any injured is maximized. Avoid trees as they are a likely target for a strike and bring the lightning current into close proximity to all nearby. --Wagionvigil
- Resovled. (Special thanks to Sysop Milominderbinder2 for the new links.) —RWSmith (Bureaucrat), 14:31, February 25, 2009 (EST)