Hi. Maybe this is a dumb question with an obvious answer, but I don’t know/remember enough to know for myself.
Lightning causes forest fires. It’s happening more and more as there are more droughts. If they can put lightning rods on buildings to protect them, could they not build a bunch of lightning rods in forests in susceptible areas? Would the lightning go into the ground and be harmless, or would it somehow still start a fire?
Cost aside, would it help prevent forest fires or no?
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TIA.
In: 6
To add to the other great answers here, I thought I’d estimate how many lightning rods would be needed to protect a forest.
We can use the *rolling sphere method* to estimate how much protection a single lightning rod gives. This method assumes that as the *leader* of the lightning bolt descends, it’s surrounded by a spherical electric field and will jump to the first suitable object that enters that field. There are simple explanations of this method [here](https://what-if.xkcd.com/16/) and [here](https://www.bondedlightning.com/rolling-sphere-method).
I’m going to assume the sphere has a radius of 45m (150ft), which seems to be the industry standard. That means a lightning rod can protect a circle of forest with radius of 45m (so the protected area is about 6,300 m^(2)).
To get a quick and dirty estimate of how many rods we need per km^(2), I’ll just divide 1 km^(2) by the area protected by each rod. We’d need 160 lighting rods per km^(2).
The total forest area in the US is 3.3 million km^(2) ([source](https://en.wikipedia.org/wiki/Forests_of_the_United_States)). If we want to protect 10% of that, 330,000 km^(2), we’d need 53 million lighting rods.
That’s not only *a lot* of lighting rods, but the places they need to be installed, remote forests, are pretty much worst-case scenario for erecting large steel structures.
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