In A Nutshell
Throughout the centuries, lightning has been mistaken for many things, from UFOs to the spirits of the dead. There are so many different kinds of lightning that it’s not surprising that sometimes people just don’t recognize it for what it is. In addition to the most common lightning that accompanies thunderstorms, there’s also the ball lightning that many see as a UFO, the jellyfish-like red sprites, blue jets that are more often seen from the sky than from the ground, and the rather disturbing dark lightning, that you may have been hit by without knowing it.
The Whole Bushel
For some people, thunderstorms are terrifying; for others, they’re an amazing display of the power of nature. We’re all pretty familiar with the lightning that goes along with most thunderstorms. (And if you live in Venezuela, you’re really, really familiar with it.) There are many different types of lightning, though, and some of them you might have seen without recognizing—or been exposed to without seeing.
The type of lightning that you probably associate with thunderstorms is called cloud-to-ground lightning, and it’s a negatively charged bolt that heads for the ground and is attracted to positively charged things there. (Heat lightning occurs when cloud-to-ground lightning happens far enough away that you can’t hear the thunder that goes along with it.) There’s also cloud-to-cloud lightning that never reaches the ground, and intra-cloud lightning that never leaves the cloud it originates in.
Sometimes, lightning has a positive charge, especially when it begins from the top of a storm cloud. When that happens, it travels along the horizon instead of coming straight to the ground, and it’s given the pretty nifty name of a bolt from the blue.
If you’ve ever seen the upper skies illuminated by a reddish flash, that’s another type of lightning called a red sprite. They’re often red as their name suggests, but they don’t have to be—and the illumination tends to last several seconds, which is much longer than most other types of lightning. Only the brightest of these are ever seen, and when they are, they’re described as looking like giant jellyfish rising from the top of the storm.
Blue jets are another type of lightning you might have seen without knowing it, especially if you fly a lot. Blue jets also shoot upward from the storm clouds, and only last for a fraction of a second. In that time, they can travel more than 40 kilometers (25 mi) above their point of origin.
If you’re a frequent flyer, you’ve probably also been exposed to dark lightning, a pretty recently explored phenomenon. You’re not going to see dark lightning, as it only lasts about 10–100 microseconds, and only occasionally gives off a telltale purple hue. What it does give off is radiation—about the same amount of radiation you’re exposed to when you get a CT scan at the hospital. It’s not a horribly scary amount, but dark lightning is most common in the same altitudes that airlines fly at, making it a potential concern.
And high above that level are the elves: massive, disk-shaped pulses of lightning that were only discovered by space shuttle cameras in 1992.
Lightning doesn’t need to be in the ionosphere in order to be mysterious, and scientists are still trying to figure out just what the heck ball lightning is and how it works. Only recently created in laboratory conditions, wild ball lightning is commonly associated with thunderstorms, but it’s also associated with other, more mystical things. It’s thought that many, many UFO sightings were actually ball lighting, as it can travel across the sky, come and go in seconds, and appear in a number of different colors. Ball lightning has also been named as a culprit in sightings of spirit lights and will-o’-the-wisps, which tend to happen over marshy areas and are said to be the evil spirits. Currently, we know that ball lightning exists, but we’re not quite sure how it’s formed and why it happens, proving that some types of lightning are just as mysterious as they were centuries ago.
Show Me The Proof
National Severe Storms Laboratory: Lightning Types
Discovery: Dark Lightning Zaps Airline Passengers
LiveScience: Mysterious Ball Lightning Created in the Lab
Mysterious Britain & Ireland: Will o’ the Wisp
National Oceanic and Atmospheric Administration: Severe Weather Safety Guide—Lightning