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How Much Energy Is Actually in a Lightning Bolt?
Nobody has ever put a probe inside the channel, and the published answers disagree by up to a factor of fifty.
Ask how much energy a lightning bolt carries and one answer comes back at a gigajoule, enough to run a house for weeks, and another at a few tens of millions of joules, enough to run it for about a day. Both ends come from careful work. The gigajoule is roughly the electrostatic energy a flash drains out of a thundercloud, and it is also, by a second route through the same physics, roughly what Vernon Cooray’s 1997 accounting assigns to a single stepped leader and its return stroke, some 5.5 × 10⁸ joules. The tens of megajoules is what most popular accounts quote for what arrives at the strike point.
Part of the spread is that the two are counting different things, the energy stored in the cloud against the energy spent in the channel, but only part: how far apart those two ledgers actually sit depends on whose estimate of the channel’s energy per metre one adopts, and those estimates disagree among themselves by two orders of magnitude.
The audit lands on two numbers, and two numbers is what an honest answer to how much energy is in a lightning bolt looks like: of order a gigajoule of stored electrostatic energy leaves the…
