SerpApi.Org
Here’s what you’ll learn when you read this story:
- Lake Maracaibo experiences constant lightning that flashes from dusk until the break of dawn, but until recently, the caused was unknown.
- Researchers found that a certain jet of wind that occurs at the same time every day carries warm air high up, where it interacts with cold air and produces an electrical discharge.
- The research team created a model to predict lighting strikes sooner than lightning has ever been predicted, making the lake safer for those who depend on it.
Under a purpling sky, Venezuela’s Lake Maracaibo basin becomes another realm as dusk encroaches. Castles of storm clouds tower above, and thunder threatens with a guttural rumble. The skies are torn open by a skeletal arm of lightning that reaches down as if trying to close its fingers around one of the many fishing boats bobbing on the surface after dark. Then it happens again. And again. And again.
Locals used to see the phenomenon as a gift sent by the gods. Relámpago del Catatumbo, or Catatumbo Lightning—named for the mouth of the Catatumbo river that empties into Lake Maracaibo—happens so predictably that ships sailing past used to use the flashes like lighthouses. After dark, skies light up 28 times a minute for up to nine hours, and someone is three times more likely to be struck by the electrical discharge there than anywhere else on Earth (which is why locals call the Catatumbo river the “river of fire”).
The phenomenon both fascinated and concerned physicist Ángel G. Muñoz. In 2015, Muñoz and his research team set out to reveal the cause of the lightning and gauge how soon lightning strikes could be predicted, so that fishing and drilling in the basin’s rich oil and natural gas reserves would not be nearly as dangerous.
“Characterizing lightning activity in different geographical regions is of great importance both for research and forecast applications,” the team said in a 2016 study published in Atmospheric Research. “There is strong evidence pointing to a relationship between flash rate and other thunderstorm parameters, such as precipitation rate [and] growing interest in studying the modulation of lightning distribution and frequency due to inter-annual phenomena.”
Lightning forms when warmer updrafts carry droplets of water to the lower end of a gathering storm—between 35,000 and 70,000 feet in the air. There, those updrafts meet cooler downdrafts laden with particles of ice from the freezing upper reaches of the storm. When updrafts and downdrafts collide, the liquid water droplets freeze, and when that ice encounters even more ascending droplets, the negatively charged electrons that are released interact with descending particles and give the base of the cloud a negative charge (as opposed to its positively charged higher layers). Static charges then build up and are eventually unleashed as lightning.
Lake Maracaibo is so prone to lightning because it always has warm water flowing in from the Caribbean Sea, and some of that water evaporates in the scorching midday sunlight. But Muñoz wanted to know why the lightning was so predictable. After sending up weather balloons, he found that the low blast of wind known as the Maracaibo Basin Nocturnal Low-Level Jet occurs around the same time every day. This warm and humid air is lofted high by winds that are forced upward by the mountains that almost completely surround the lake. When it meets the cold air above, the buildup of static charges eventually explodes into electrical discharge.
Muñoz and his team used data from NASA satellites to design a model based on lightning frequency triggers. They incorporated water surface temperature, wind, humidity, and Convective Available Potential Energy (CAPE), which is a measure of atmospheric instability that predicts the strength of the updrafts powering an impending thunderstorm. CAPE and the Nocturnal Low-Level Jet turned out to be the most obvious causes of the lightning storms that electrify Lake Maracaibo 140 to 160 nights a year, and the scenario in which the jet caused the advection (or the horizontal transport) of CAPE resulted in the most accurate version of the predictive model.
Previously, the furthest out lightning could be predicted was days, though more often, it could only be reliably predicted hours in advance. Muñoz was able to extend that timeline to three months. Providing warnings that far ahead can better prepare fishermen, oil workers, and others whose livelihoods depend on the lake. Crossing a lake the size of Connecticut to refuel a fishing boat, for instance, can take hours. Risk can be drastically reduced if that trip is planned around lighting storms.
“It is found that the predictive skill is slightly higher for the minimum lightning season (Jan–Feb) than for the maximum one (Sep–Oct),” Muñoz said, “but that in general the skill is high enough to be useful for decision-making processes related to human safety, oil and natural gas exploitation, energy and food security.”
