Behind the Forecast: Lightning’s true power

Listen to Science Behind the Forecast with Meteorologist Tawana Andrew every Friday on 89.3 WFPL at 7:45 a.m.
Published: Jul. 3, 2020 at 10:02 AM EDT
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LOUISVILLE, Ky. (WAVE) - Lightning is one of the most dangerous aspects of the weather. 

Lightning is the quick discharge of electrical energy in the atmosphere. The following boom of thunder is caused by a shock wave created by the rapid heating then cooling of the air in a lightning channel.

In the lower 48, an average of 20,000,000 cloud-to-ground flashes has been detected every year since the lightning detection network (NLDN) covered all of the continental US in 1989, according to The National Severe Storms Laboratory. 

Lightning is HOT!
Lightning is HOT!(WBRC)

Between 2009 and 2018, the U.S. averaged 27 lightning fatalities, according to the National Weather Service. Lightning contains between one to 10 billion joules of energy which can easily short-circuit the electrical signals vital for our nervous system, heart, and lungs to function. While only around 10% of lightning victims die, survivors can face a lifetime of pain, depression, neurological problems, and other health issues.

I broke down the multiple ways to get struck by lightning in a previous Science Behind the Forecast. They are a direct strike (which is the most deadly), ground current, conduction, side flash, and streamers. 

The World Meteorological Organization (WMO) recognized two lightning records in June 2020: for the longest reported distance that lightning has traveled and for the longest duration for a single lightning flash. These “megaflashes” were verified with new satellite lightning imaging technology. Megaflashes are defined as “horizontal mesoscale lightning discharges that reach 100s of kilometers in length.”

WMO’s Committee on Weather and Climate Extremes maintains the official records of global, hemispheric, and regional extremes. The committee found that the farthest horizontal distance that lightning has traveled on planet Earth is 709 ± 8 kilometers or 440.6 ± 5 miles. This lightning strike occurred on October 31, 2018, in southern Brazil. That’s approximately the distance between Boston and Washington D.C.; the lightning strike was longer than the drive from Louisville, Kentucky to Atlanta! 

The previous record for the longest detected distance for a single lightning flash was for 321 km or 199.5 miles in Oklahoma on June 20, 2007.

Lightning can strike miles from a storm
Lightning can strike miles from a storm(WBRC)

A single lightning flash lasted for 16.73 seconds; it developed over northern Argentina on March 4, 2019. That’s the longest duration on the planet. 

The previous record for the longest continuous single lightning flash duration was 7.74 seconds over Provence-Alpes-Côte d'Azur, France, on August 30, 2012.

For context, a lightning strike lasts on average for 30 microseconds, according to scientists at Arizona State University. 

These records are more evidence that we should all follow the mantra “When Thunder Roars, Go Indoors.”

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