[♪INTRO].

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. [♪OUTRO].