Lightning is one of the most terrifying natural phenomena that humans fear from ancient times. Its strong luminous brightness and its association with the sounds of thunder sometimes create fear in the soul. These fears are heightened by fires and fatal accidents that may sometimes be caused.
While people are ignorant of its nature, many do not realize that lightning has vital benefits as well, interceding for all the fear it causes and the losses it causes on earth. Also, lightning as a natural phenomenon possesses several exciting secrets, some of which may reinforce the fear that has accumulated around it, and some of them may mitigate the darkness of the stereotype around it in popular culture.
According to Al Jazeera Net, lightning is more than just a light show, as lightning plays an important role in maintaining the electrical balance of the earth, and it also contributes to nitrogen fixation, which helps plants grow, and it is likely that it will also help cleanse the atmosphere of pollutants.
According to the UK Met Office, lightning strikes the planet 1.4 billion times a year, or an estimated 44 times every second. But some lightning flashes are longer and larger than others.
While most lightning flashes are 3.2 to 4.8 kilometers in length, others occasionally surge and make their way across hundreds of kilometers in the sky above our heads. But how big can lightning actually reach? And should we worry about these giant thunderbolts?
How does lightning form?
Lightning arises in storm clouds when a strong positive charge develops in one area of the cloud and a strong negative charge develops in another area, creating electric forces between them.
“The flash of lightning begins in an area where the electric forces are very strong,” says Don McGorman, a physicist and senior researcher at the National Oceanic and Atmospheric Administration (NOAA) National Storm Laboratory in Oklahoma. It becomes strong enough that the air can no longer handle the wattage and it collapses or malfunctions.”
This means that as the wattage grows, McGorman says, it breaks up the dielectric strength of air, which usually keeps regions of different charges separate from one another. The researchers believe this happens because the buildup of excessive electrical force begins to accelerate “free” electrons not attached to an atom or molecule in the air, which in turn causes other electrons to escape from their atoms and molecules. This process continues, causing more and more electrons to be accelerated. Scientists call this process “electron breakdown,” hence the name “air breaks down.”
This eventually creates a very hot channel in the air that acts like a wire, the ends of which grow outward toward the positive and negative charges that cause the breakdown. The growing channel eventually connects the positive and negative charges, and when it does, it releases the massive electric current we know as a flash of lightning.
Sometimes the lower part of the cloud, which usually contains a positive charge, does not have enough charge on its own to stop this channel. So the lightning bolt continues to grow, and extends downward toward the ground.
As it does so, it attracts a spark rising from the ground to confront it, causing a flash of lightning with massive electric currents that transfer some of the storm’s charge back to Earth.
What factors limit the size of lightning storms?
According to an article published on the “Live Science” website, researchers have been trying to answer this question for decades. Looking vertically, the extent of the lightning flash is limited by the height of the storm cloud, or the distance from the ground to the top of this cloud, which is about 20 kilometers at its highest. But horizontally, the cloud’s size provides more space to spread through.
In 1956, Myron Legda, a Texas meteorologist, used radar to detect a flash of more than 160 km. It was the longest flash of lightning ever recorded at the time. Since then, technological advances have allowed researchers to measure the longer flashes as well as the greater number of them.
In 2007, researchers identified a lightning bolt over Oklahoma, USA, with a length of 322 km. But only a decade later, that record was erased, because in October 2017, clouds over the American Midwest unleashed a flash of lightning so massive that it lit up the skies over Texas, Oklahoma and Kansas.
The tremor extended for more than 500 kilometers across the three states, and was so unprecedented that a group of researchers published a study on it in the Bulletin of the American Meteorological Society, describing it as a “megaflash.” It was one of the largest flashes of lightning ever recorded.
But even this flash was bypassed because on October 31, 2018, a lightning bolt was detected over Brazil that extended more than 709 kilometres. But once again this record was broken by another giant launch on April 29, 2020, a gigantic flash that stretched from Texas to Mississippi, and covered 768 kilometers.
Lightning has traditionally been observed via terrestrial systems such as antennas and radar, but many of these record-breaking flashes are now being recorded using satellites.
Giant lightning flashes
Researchers are still unsure of the exact mechanisms that underpin such long electric illumination, and cloud size is almost certainly a factor.
The larger the original cloud, the greater the chance of a flash of lightning continuing to spread, says Christopher Emersick, a researcher who studies electrification of thunderstorms at the University of Manchester in the United Kingdom, which is why massive flashes can be as large as the original cloud, if the charging structure is appropriate. This means that there are likely to be much larger flashes than were actually recorded.
Despite the horrific picture they paint, Emersic says, the massive flashes aren’t necessarily more dangerous than ordinary lightning. A wide spatial flash does not necessarily mean that it carries more energy. Because the cloud from which it arose is very wide, this can lead to ground strikes far from the main lightning activity in the convection core.
According to McGorman’s estimation, massive flashes are not currently uncommon. They make up only about 1% of lightning flashes overall.
It’s also possible that in a warming world, Emersek says, there may be an increase in the types of storms that lead to massive flashes. This makes conditions more likely to increase their frequency and spread.