Pete_Hickey said:
When a bolt has travelled thousands of feet, small things such as crouching, ground insulation, etc will have a negligable effect (items 6 and 7 on that page) . You're talking about huge voltages that do whatever they want.
True to a certain extent. The path of lightning is set by a sequence of short "leader" dischagres--the main bolts usually follow the leader path. These leader discharges take the "easiest" path (which is not obvious to humans and not a straight line). There are certain generalities that influence the probablity of a spot being hit. All else being equal, anything that sticks up above the surrounding terrain (eg a lightning rod, a peak, a ridge, a tall tree, a boat out on the water, a person standing on a ridge, a person standing in a flat field, etc) is more likely to be hit. Whether the object is metal or not makes little difference--besides, any wet object is conductive enough.
A pole (metal or not) sticking up will probably increase your chance of being hit somewhat. Metal next to your body (eg a pack frame) will probably have little effect on your chance of being hit. However, metal objects can affect the route of the currents, so you might get skin electrical burns near metal on or close to your body.
There is another factor--ground currents. When there is a ground strike, the charge has to be dissipated. So just being near the strike point can result in a serious or fatal shock. Crouching down (to reduce the chance of a direct strike) on a sheet of metal (to route the current abound you) or on an insulating sheet (to reduce the amount of current that goes through you) reduces the chance of injury. Also avoiding caves (wet cracks may route ground currents into them), streams, ditches (the voltage can be higher across a ditch), etc reduces the chance of injury from ground currents.
When a ground current flows, the voltage between two points is approximately proportional to the distance along the current path between the two points. So, supporting yourself on one foot is best (no hands or poles for balance...), two feet right next to each other is better than two feet spread apart. Don't forget that holding hands or just touching one another provides a good path for ground currents...
The strike can also take multiple hops--for instance, a bolt can hit a tree, travel part way down the tree, and then jump to something else--including you.
The heat from the current can vaporize water in tree trunks and cause them to explode or cause a strip of bark to explode off. Damp clothing can also be blown off.
Moving vs stationary probably makes little difference. The best strategy is generally to move away from a bad spot toward a better spot. If you are in a relatively safe spot and the route ahead looks less safe, consider stopping and waiting the storm out.
Yes, lighting can, and often does, strike the same spot multiple times. If it hit here once, then "here" is not a good place to be...
A car is fairly safe, not because of the rubber tires (a 1000ft spark isn't going to be bothered by a 6in gap), but because of the metal cage around you.
When a group is "hit", it is frequently due to ground currents. (The bolt itself may be more localized.)
Spreading a group out is a good idea--that way if someone is struck, others are available for rescue. If you stay in a tight group, all or most can be incapacitated.
Lightning shocks the brain and heart. A sufficient shock to the brain will stop breathing. The heart clamps down and wil usually restart on its own (but will stop if breathing does not resume). Immediate treatment should be directed toward those who are not breathing and appear dead--if they are moving or groaning they do not require immediate attention. Artificial respiration is required for the non-breathers, possibly for an extended period. Add CPR if the heart stops. Most survivors have no significant residual disabilities, but lighting victims can have severe long-term problems, so they should get a medical checkup. (Paraphrased from Wilkerson.)
More info on treatment in Wilkerson, "Medicine for Mountaineering".
Doug
