Why should I squat instead of laying flat on the ground during a thunderstorm?
In: Physics
Your shoes, if you have them on should provide some insulation, and reducing your surface area contact with the reduces your likely hood of being in the sapce to pick up a ground hit charge as the electric quickly dissipated across mediums, specially if the ground is soaked in water.
If lightning hits the ground next to you you don’t want to be a shortcut for current distributing in the soil.
When lightning hits the ground there will be circles of diminishing electrical potential around it. If one part of your body is closer to the lightning strike than another then this means your body experiences a net voltage and that can kill you. Your feet should be as close together as possible.
Because lightning can cause voltage gradients across the surface of the ground, and if your head is at a different voltage to your feet, current will flow from one to the other.
Ideally you would be balancing on one toe, but since that’s a little difficult the next best thing is to crouch with your feet close together.
You want as little ground contact as possible to reduce the area where a potential difference between your body and the ground allows current to flow.
Ideally you want zero ground contact. But unless you jump right the moment the lightning hits the next best thing is standing on your feet. You stand close together and not spread apart that in the event some current flows through you it doesnt travel from one foot all the way through your body to the other foot but rather from your one feet to your ankles and back through the other foot. You squad and dont stand tall to not give lightning a chance to use you as a lightning rod
Because you will be a smaller target crouching than lying flat. Additionally if you are wearing rubber soled shoes you’ll be better insulated if only your feet are touching the ground and thus less likely to be a conduit for the electricity.
There’s a pretty good analogy with explosions here. A vacuum sucks air in because the air is less dense inside than outside (at the same temperature). An explosion is similar – a combination of generating a bunch of gas and causing a sudden in temperature results in a large pressure gradient between the origin of the explosion and its surroundings. The surroundings, like a vacuum, suck up the explosion.
The thing that makes an explosion dangerous is that part of you is getting pushed/pulled hard before the rest of you can follow suit, tearing you apart. The more you can mold yourself to the shape of the pressure wave, and the thinner you are, you reduce the pressure gradient so you get accelerated evenly.
A lightning strike is very similar. It dumps a huge amount of charge into a point on the ground. The ground had a relatively even opposite charge before the lightning strike, so parts of the ground that are further away from the lightning strike will suck up the charge from the lightning, causing the lightning’s charge to spread outwards from the point where it struck.
If you have two feet on the ground, there’s a possibility that the lightning strikes in a place where one foot sucks up the charge before the other one can. But instead of you being pushed/pulled unevenly by a pressure wave, the foot that’s further away from the lightning strike may suck up some charge from the foot that’s closer, and it may do so through your body instead of the ground.
That flow of charge is what basically burns you from the inside and overloads the electrical channels that are normally responsible for operating your muscles, including your heart.
Standing on one foot minimizes how much charge one part of your body can suck up before the rest of your body can catch up, minimizing the difference in charge between the most and least charged parts of your body, which in turn limits how much charge flows through you. It also helps limit the path of the charge to just that foot, as those two points are so close together. Squatting is just an easier way to get most of the benefit.
Adding to the excellent answers already given – this is why four-legged animals (cows, horses, sheep) are so badly affected by nearby lightning strikes. There will always be a ground potential difference between their fore and hind legs, and the heart is on that path.
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