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Imagine living in a place where you’re surrounded
by the sharp smell of ozone and hot, dry air.
And around 300 nights per year, the sky is
lit up by nearly 10 hours of continuous lightning
strikes that can be seen from hundreds of
kilometers away.
In fact, during peak thunderstorm season,
an average of 28 lightning strikes per minute
hit the surface of Venezuela’s Lake Maracaibo.
This lake and its weird lightning have been
a scientific mystery for decades.
But nowadays, researchers think that a perfect
storm of environmental factors is causing
this everlasting light show.
The phenomenon is known as Catatumbo lightning,
named after the river that flows into the
southern part of Lake Maracaibo.
It’s been recorded as early as 1598, when
the poet Lope De Vega recounted how it helped
thwart a surprise attack by the English privateer
Sir Francis Drake.
And on a molecular level, Catatumbo lightning
is pretty normal.
Lightning is a buildup and release of electric
charge between one cloud and another, or between
clouds and the surface of the Earth.
When rain and icy dust particles collide during
a thunderstorm, the clouds become polarized,
with clusters of positively and negatively
charged particles.
Basically, we think that upward currents of
air push some molecules skyward, while heavier
particles drop down and collide with them,
snagging electrons along the way.
Since electrons are negatively charged, the
bottom of the cloud gets more negatively charged,
and the top gets more positively charged.
And because like repels like... the negative
bottoms of these clouds repel electrons on
the ground, trees, or buildings below, leaving
them with a more positive charge.
And all this charge separation keeps building
up, creating a strong electric field.
Most of the time, this leads to negative lightning,
where streams of negative charges from the
bottom of the cloud branch toward the Earth.
That negative stream is met by an opposite
stream of positive charges flying skyward.
And when that happens, they exchange energy
that manifests as a bright lightning strike.
These strikes can heat the surrounding air
to a ridiculously high temperature of nearly
30,000°C — around five times hotter than
the surface of the Sun.
Now, scientists have been baffled by the fact
that Catatumbo lightning happens in the same
place night after night, with an estimated
1.2 million strikes per year.
One Venezuelan scientist who surveyed the
area in the 1960s took a guess that uranium
deposits in the nearby bedrock might act like
a lightning magnet, drawing a disproportionate
number of ground strikes.
But that idea was a dead-end.
Another researcher thought that all this lightning
was thanks to an excess of methane oozing
up from nearby oil fields and swamps.
Specifically, he thought that methane’s
molecular geometry increased the separation
of positive and negative charges inside the
storm clouds, which is an important step in
making lightning.
But neither of these hypotheses have been
thoroughly supported by other scientists,
so they fall short to a simpler explanation.
Nowadays, researchers mostly attribute Catatumbo
lightning to the area’s unique topography
— the shape of the Earth’s surface in
a given area.
Many of the world’s lightning hotspots are
linked to geographical features like curved
coastlines and nearby mountain ranges, plus
winds that help cook up thunderstorms.
Lake Maracaibo is surrounded by the Andes
mountains and other branching ranges to the
south, west, and east, and they trap warm
winds flowing over the lake from the Caribbean Sea.
When that warm, damp air collides with the
colder mountain air, it rises quickly into
the atmosphere, helping thunderclouds form
in this stormy sweet spot.
So Lake Maracaibo probably just has all the
ingredients for a thunderstorm almost every
day of the year — and that’s the reason
for all this lightning.
Besides being a natural marvel, some scientists
also argue that the Catatumbo lightning might
play a critical role in generating ozone in
the atmosphere.
Ozone is a molecule made from three oxygen
atoms, and helps contribute to a protective
shield around the Earth in the upper atmosphere.
And the ozone layer absorbs potentially harmful,
high-energy ultraviolet rays from the Sun
before they reach the planet’s surface and
cause damage to living things.
When a lightning bolt rips down from the clouds
and heats the nearby air, the energy release
triggers chemical reactions that produce nitrogen
oxides, which can then react with other molecules
to form ozone.
So Lake Maracaibo’s other claim to fame
might be that it’s the largest natural source
of ozone in the world.
But most scientists say that this probably
won’t help with human-caused ozone depletion,
because that lightning-generated ozone doesn’t
make it into the upper atmosphere.
So Lake Maracaibo has become quite the tourist
attraction.
But for scientists, it’s a chance to dive
deeper into why some parts of the world are
a little more electric than others.
Thanks for watching this episode of SciShow!
If you want to learn about more weird places
hidden on Earth, check out this compilation
of 6 of our videos about them!
And don’t forget to go to youtube.com/scishow
and subscribe.
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