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It is believed that one lightning bolt can carry enough energy to light a 100W bulb for 3 months. Why do so many people get directly hit by lightning bolts and survive?

One argument can be, the electric shock period is really small (a fraction of a second) but on the other hand, if someone is hit by lightning bolt from a high tension wire for example, he is almost instantly killed.

That lightning is also for a very short period of time.

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    \$\begingroup\$ Possibly it is emitted as a high frequency discharge, where the "skin" effect would apply to some extent. I've seen some examples of lightning in radio frequencies, however it is just speculation. \$\endgroup\$
    – Transient
    Feb 20, 2012 at 5:10
  • \$\begingroup\$ Old question, but got bumped to the top due to edit. The existence of lichtenberg figures on the skin may indicate that the path the bolt takes through the body may not be through the body as much as on it.. While the burns are bad, it is possible that it avoids the internal organs in many cases. \$\endgroup\$
    – crasic
    Aug 5, 2013 at 0:09
  • \$\begingroup\$ Also, there is a difference between stray high power bolt from a thunderstorm and the majority of thunder related deaths, that is, caught inside a thunderstorm when at elevation. Its a scary place, the air hums (audibly) from the static electricity build up in the air, you feel stray charges running across you, as your hair stands on end. Its not just for convenience that many popular hiking peaks around the world have summit shelters \$\endgroup\$
    – crasic
    Aug 5, 2013 at 0:11

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Not all shocks are created equal. Some "direct hits" are more direct than others. I'm just guessing here, but I would bet real money that if a lightning bolt hit within 4 feet of a person then it would be called a "direct hit". It is entirely possible that a lightning bolt that hits 4 feet away will cause injury, but not death. It is also possible that it will be fatal, even at 4 feet.

A big factor is WHERE the electrical energy flows, and how much energy. If you get struck directly in the leg (a real "direct hit") and that energy never flows through your brain or heart then you might survive. You could also have the energy flow through the skin of your torso but never reach your heart, and still survive.

But even if you have a "near miss", there is still a significant amount of energy that could pass through or on your body. The bolt itself can be quite wide, and not all of it is visible. The bolt can cause an electro-magnetic field that can induce electrical currents in things nearby (or very far away, in the case of lightning detectors). Once the bolt hits the ground, it can flow along the ground for some distance. And of course there are the non-electrical things like the blast of heat, light, and sound that could cause other issues. So even a "near miss" can cause damage and injury.

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  • \$\begingroup\$ I asked this question particularly that I read ppl got bolted because of tongue piercing. (it hit the tongue directly). They survived.example \$\endgroup\$
    – engineer
    Feb 20, 2012 at 12:22
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The key difference as compared to being electrocuted from a high tension wire is that the "far terminal" of the discharge is very far away and that voltage is much higher. This leads to a curious effect - the bolt gets stranded (look at a picture of Tesla coil discharge for a better image of what I'm talking about).

When a discharge gets from a high-tension wire - it goes from the wire through a person and to the ground where the person stands, so all energy is passing through the person. When a lightning strikes - the discharge starts somewhere far in the sky and goes to the ground and near the ground a huge volume of air gets ionized and forms conductive strands. The discharge goes from somewhere in the sky to a wide area on the ground.

So for example if there's a tree near a house and a lighting strikes into the tree the discharge can also pass through the tree branches to a house wall and set the wall on fire. So to protect a house not only lightning protection should be installed, but all nearby trees should be trimmed to avoid this effect.

Add to this that air can easily conduct tremendous currents when ionized enough but the human body has limited conductivity and the human body is not necessarily the least resistance path. So when a lightning strikes anything that anything is usually only one of the multiple paths for the current, not the only one.

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The theory behind lightning strikes is tremendously complex. You're asking "why people survive". It seems that you somehow think that lightning strike is by definition lethal. However, the question "why would someone die when struck by lightning" is even more interesting.

In a simplified view, you can think about lightning as of huge current source, and about our body as of resistor. In general, if the lightning strikes you directly and all the charge released during the discharge flows through your body, the damage will be severe. However, the damage may be localized to a particular area of the body - it depends how exactly the current flows inside the body.

The body may be modeled as a distributed resistors network:

enter image description here

The ultimate destination of lightning's charge is the ground, therefore you can estimate (very roughly) the path of current flow inside your body as a function of lightning's hit point. For example: if the lightning hits your leg, the current won't flow into your head, therefore the brain damage will be reduced (it is very simplified model! when someone is struck by a lightning, its whole body may become a temporary storage of the charge, in which case stochastic currents flow all over your body).

Until now we assumed that all the charge of the lightning flows through your body, but it is rarely the case. If you're wet, the resistance of the external layers of your skin is much less than the resistance of the body itself. This resistance is in parallel to body's resistance. It means that the majority of the current will flow "on the body" and not "inside the body". While this is still very dangerous (and may easily be lethal), the fact that the majority of the current do not penetrate into the body rises you chances to survive dramatically.

Any additional conducting path to the ground in man's vicinity when he is struck by the lightning also present additional parallel resistance for current flow and increases chances for survival.

Follow this link to find additional info on lightning injuries.

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