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Few natural events are as memorable as thunderstorms.
Between the impossibly-bright flashes of lightning and the bone-shaking rumbles
of thunder, you might agree that dogs who hide under the table have the right idea.
But, incredibly, these powerful events are just
the starter pack of “electricity coming from the sky.”
A hundred, or even a thousand, times more intense
than your garden-variety lightning are so-called superbolts
And they have scientists pretty stumped.
They’re not just more powerful; superbolts also seem to
strike on totally different parts of the planet.
Scientists don’t know why that happens, or even why superbolts happen at all.
The answer might also help clear up
some lingering mysteries about the causes of lightning itself.
Over the last couple centuries, scientists have worked out
a pretty detailed understanding of how a bolt of lightning comes to be.
It begins with sunlight warming the planet,
which heats humid air near the ground until that air starts to rise.
Once humid air reaches an altitude that’s cold enough for water vapor
to condense into droplets and freeze into ice crystals, clouds start to form.
Sometimes, as the water condenses,
it keeps rising, which leads to the super-tall shape of a thunderhead.
All that rising and cooling makes the ice crystals
bump into one another inside the cloud as they swirl around.
And just like rubbing your socks on the carpet,
those crystals transfer little bits of electric charge between them.
After a while, enough of one type of charge builds up at the bottom of the cloud
that some charge is forced into the nearby air.
That kicks off a cascade of electrically-charged air that
eventually either reaches the ground or another cloud.
Once it does, a big, bright flash of electric current travels along the path.
That’s a lightning bolt.
But superbolts seem to break all these rules.
Normal lighting tends to form in the summer, over land,
since land heats up faster than water does,
enabling humid air to rise more quickly when it starts over the land.
And, since warmth and humidity are both contributing factors,
it’s no surprise that lightning happens most commonly in the tropics.
But superbolts are mostly found in the winter,
over the ocean, off the coast of Europe.
Which is definitely not the setting for a tropical paradise.
And, yet, somehow, superbolts are hundreds of times
more powerful than ordinary lightning.
It’s so weird that some scientists wondered
if they’re a statistical fluke or some kind of measurement error.
But that doesn’t seem to be happening.
Superbolts are found by the same network of sensors that map
any other kind of lightning, the same ones that find more
regular lightning over land during tropical summers.
Those sensors detect radio waves that spread out from a lightning bolt.
The louder the radio signal, the bigger the bolt.
Which leaves atmospheric scientists with
a pretty big puzzle without an obvious path forward.
Some have proposed that pollution from all the ships passing through
the English Channel helps clouds build up
absurd amounts of charge before they start sparking.
Or it might be that clouds with salty ocean water lose all of their charge
in a bolt while normal thunderclouds only lose some of their charge.
Or it could be that there’s something we fundamentally
don’t understand about lightning.
Because, although scientists have worked out the big picture
for lightning pretty well, there are a lot of details that don’t perfectly line up.
Like the fact that the bottom of a cloud
usually becomes negatively charged, but not always.
Some lightning is positively charged, and some has a mix of both.
Superbolts seems to break the rules here, too.
The more powerful a superbolt is, the more likely it is to be positively charged.
So it’s possible that something about the way
a cloud charges has an effect on how big the lightning can get.
But it’s also possible that physicists are
looking at the whole problem the wrong way.
Experiments have shown that charge builds up
in a thundercloud until the air near the cloud breaks down.
But they’ve also shown that there’s not nearly enough energy
in a typical lightning bolt to make that happen.
It doesn’t seem like lightning should even be possible
until it’s somewhere in between a regular bolt and a superbolt.
There are possible explanations for this, like charge building up only in specific
parts of clouds, or an incoming cosmic ray from space kickstarting the process.
Or it could be something totally different.
The existence of an even more powerful kind of lightning
could be the clue scientists need to figure it out.
And that’s how science works sometimes.
A new piece of evidence can force you to
totally reevaluate your view on the problem.
Like, maybe scientists shouldn’t be asking why superbolts are so big.
The real question might be: how can regular lightning be so small?
Questions like those can be helped along by honing your reasoning skills.
And to do that, you might enjoy Brilliant’s course on Logic.
Like many of their courses, Brilliant has recently taken
the interactivity of this one to the next level,
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Brilliant has a bunch of courses in science, engineering, math,
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to all the exercises so you can identify how to arrive at the right answer.
To get started, head to brilliant.org/scishow to save 20% off
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