Detailed Footage Finally Reveals What Triggers Lightning (quantamagazine.org) 45
An anonymous reader shares an excerpt from a report via Quanta Magazine, written by Thomas Lewton: During a summer storm in 2018, a momentous lightning bolt flashed above a network of radio telescopes in the Netherlands. The telescopes' detailed recordings, which were processed only recently, reveal something no one has seen before: lightning actually starting up inside a thundercloud. In a new paper that will soon be published in the journal Geophysical Research Letters, researchers used the observations to settle a long-standing debate about what triggers lightning -- the first step in the mysterious process by which bolts arise, grow and propagate to the ground. "It's kind of embarrassing. It's the most energetic process on the planet, we have religions centered around this thing, and we have no idea how it works," said Brian Hare, a lightning researcher at the University of Groningen and a co-author of the new paper. [...]
[Joseph Dwyer, a physicist at the University of New Hampshire and a co-author on the new paper] and his team turned to the Low Frequency Array (LOFAR), a network of thousands of small radio telescopes mostly in the Netherlands. LOFAR usually gazes at distant galaxies and exploding stars. But according to Dwyer, "it just so happens to work really well for measuring lightning, too." When thunderstorms roll overhead, there's little useful astronomy that LOFAR can do. So instead, the telescope tunes its antennas to detect a barrage of a million or so radio pulses that emanate from each lightning flash. Unlike visible light, radio pulses can pass through thick clouds. Using radio detectors to map lightning isn't new; purpose-built radio antennas have long observed storms in New Mexico. But those images are low-resolution or only in two dimensions. LOFAR, a state-of-the-art astronomical telescope, can map lighting on a meter-by-meter scale in three dimensions, and with a frame rate 200 times faster than previous instruments could achieve. "The LOFAR measurements are giving us the first really clear picture of what's happening inside the thunderstorm," said Dwyer.
A materializing lightning bolt produces millions of radio pulses. To reconstruct a 3D lightning image from the jumble of data, the researchers employed an algorithm similar to one used in the Apollo moon landings. The algorithm continuously updates what's known about an object's position. Whereas a single radio antenna can only indicate the rough direction of the flash, adding data from a second antenna updates the position. By steadily looping in thousands of LOFAR's antennas, the algorithm constructs a clear map. When the researchers analyzed the data from the August 2018 lightning flash, they saw that the radio pulses all emanated from a 70-meter-wide region deep inside the storm cloud. They quickly inferred that the pattern of pulses supports one of the two leading theories about how the most common type of lightning gets started.
One idea holds that cosmic rays -- particles from outer space -- collide with electrons inside thunderstorms, triggering electron avalanches that strengthen the electric fields. The new observations point to the rival theory. It starts with clusters of ice crystals inside the cloud. Turbulent collisions between the needle-shaped crystals brush off some of their electrons, leaving one end of each ice crystal positively charged and the other negatively charged. The positive end draws electrons from nearby air molecules. More electrons flow in from air molecules that are farther away, forming ribbons of ionized air that extend from each ice crystal tip. These are called streamers. Each crystal tip gives rise to hordes of streamers, with individual streamers branching off again and again. The streamers heat the surrounding air, ripping electrons from air molecules en masse so that a larger current flows onto the ice crystals. Eventually a streamer becomes hot and conductive enough to turn into a leader -- a channel along which a fully fledged streak of lightning can suddenly travel. Ute Ebert, a physicist at Eindhoven University of Technology in the Netherlands who studies lightning initiation but was not involved in the new work, notes, however, that despite its resolution, the initiation movie described in the new paper does not directly image ice particles ionizing the air -- it only shows what happens immediately afterward. "Where is the first electron coming from? How does the discharge start near to an ice particle?" she asked.
Few researchers still favor the rival theory that cosmic rays directly initiate lightning, but cosmic rays could still play a secondary role in creating electrons that trigger the first streamers that connect to ice crystals, said Ebert. Exactly how streamers turn into leaders is also a "matter of great debate," said Hare.
[Joseph Dwyer, a physicist at the University of New Hampshire and a co-author on the new paper] and his team turned to the Low Frequency Array (LOFAR), a network of thousands of small radio telescopes mostly in the Netherlands. LOFAR usually gazes at distant galaxies and exploding stars. But according to Dwyer, "it just so happens to work really well for measuring lightning, too." When thunderstorms roll overhead, there's little useful astronomy that LOFAR can do. So instead, the telescope tunes its antennas to detect a barrage of a million or so radio pulses that emanate from each lightning flash. Unlike visible light, radio pulses can pass through thick clouds. Using radio detectors to map lightning isn't new; purpose-built radio antennas have long observed storms in New Mexico. But those images are low-resolution or only in two dimensions. LOFAR, a state-of-the-art astronomical telescope, can map lighting on a meter-by-meter scale in three dimensions, and with a frame rate 200 times faster than previous instruments could achieve. "The LOFAR measurements are giving us the first really clear picture of what's happening inside the thunderstorm," said Dwyer.
A materializing lightning bolt produces millions of radio pulses. To reconstruct a 3D lightning image from the jumble of data, the researchers employed an algorithm similar to one used in the Apollo moon landings. The algorithm continuously updates what's known about an object's position. Whereas a single radio antenna can only indicate the rough direction of the flash, adding data from a second antenna updates the position. By steadily looping in thousands of LOFAR's antennas, the algorithm constructs a clear map. When the researchers analyzed the data from the August 2018 lightning flash, they saw that the radio pulses all emanated from a 70-meter-wide region deep inside the storm cloud. They quickly inferred that the pattern of pulses supports one of the two leading theories about how the most common type of lightning gets started.
One idea holds that cosmic rays -- particles from outer space -- collide with electrons inside thunderstorms, triggering electron avalanches that strengthen the electric fields. The new observations point to the rival theory. It starts with clusters of ice crystals inside the cloud. Turbulent collisions between the needle-shaped crystals brush off some of their electrons, leaving one end of each ice crystal positively charged and the other negatively charged. The positive end draws electrons from nearby air molecules. More electrons flow in from air molecules that are farther away, forming ribbons of ionized air that extend from each ice crystal tip. These are called streamers. Each crystal tip gives rise to hordes of streamers, with individual streamers branching off again and again. The streamers heat the surrounding air, ripping electrons from air molecules en masse so that a larger current flows onto the ice crystals. Eventually a streamer becomes hot and conductive enough to turn into a leader -- a channel along which a fully fledged streak of lightning can suddenly travel. Ute Ebert, a physicist at Eindhoven University of Technology in the Netherlands who studies lightning initiation but was not involved in the new work, notes, however, that despite its resolution, the initiation movie described in the new paper does not directly image ice particles ionizing the air -- it only shows what happens immediately afterward. "Where is the first electron coming from? How does the discharge start near to an ice particle?" she asked.
Few researchers still favor the rival theory that cosmic rays directly initiate lightning, but cosmic rays could still play a secondary role in creating electrons that trigger the first streamers that connect to ice crystals, said Ebert. Exactly how streamers turn into leaders is also a "matter of great debate," said Hare.
3 dupes on front page (Score:4, Informative)
Three of the stories on the front page, including this one, are dupes.
Is that a record?
Re: (Score:2)
Three of the stories on the front page, including this one, are dupes.
Is that a record?
Could be a Christmas thing.
Re: (Score:2)
Could be a Christmas thing.
Yeah, let's face it - the bible includes multiple dupes of the Christmas story.
Re: (Score:2)
Re:3 dupes on front page (Score:5, Funny)
Re: (Score:2)
That is perhaps the most well thought-out and best-executed 'Funny' post I've ever seen on Slashdot. Well done!
This is not the front page other Slashdotters... (Score:2)
Really? What was Funny about that?
Anyway, I frequently (well, daily) review the front page from top to bottom, and I'm NOT seeing so many dupes. I strongly suspect "This is not the front page that other Slashdotters are searching for and seeing." Perhaps someone is playing with the code again? Maybe he's seeing candidate stories?
Of course complaining vigorously about whatever he's seeing is in the "best" tradition of Slashdot.
Oh yeah. Why scan the entire front page? I'm looking for the heavily commented sto
Re: (Score:1)
Is that a record?
Yes. It's this one [discogs.com], because at this point I think the /. editors are trolling us on purpose.
I blame crypto bros aka "web 3" (Score:2)
The crypto bros like to yammer on and on about the same garbage, over and over again. Because of that, people get used to hearing the same things over and over - they largely lose their ability to recognize duplication because they've learned to actively filter it out as a necessary means to preserve their sanity.
Re: (Score:2)
It's the law!
https://en.wikipedia.org/wiki/... [wikipedia.org]
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Whatever triggers lightning (Score:3, Funny)
We'd better make sure not to offend it. Please make sure you use lightning's proper pro-noun which is "oh fuck that scared the shit out of me".
Re: (Score:1)
"...but i heared that lightin n birds don't exist, the TV said so..."
Don't destroy religions. (Score:2)
>> we have religions centered around this thing, and we have no idea how it works
It's precisely BECAUSE we have no idea how it works that we have religions centered around it.
Don't destroy religions.
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We'd better make sure not to offend it. Please make sure you use lightning's proper pro-noun which is "oh fuck that scared the shit out of me".
Not to worry, we can just steal it's thunder.
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Iron Maiden promised not to, a long time ago and nobody disagrees with Eddie. For long.
Detailed Analysis Reveal What Causes Dupes (Score:1)
BeauHD.
Re: (Score:2)
If this had been a crypto story, I would have agreed. He's infamous for posting everything he can find on that BS.
Hollywood lightning. (Score:3)
When thunderstorms roll overhead, there's little useful astronomy that LOFAR can do. So instead, the telescope tunes its antennas to detect a barrage of a million or so radio pulses that emanate from each lightning flash. Unlike visible light, radio pulses can pass through thick clouds. Using radio detectors to map lightning isn't new; purpose-built radio antennas have long observed storms in New Mexico. But those images are low-resolution or only in two dimensions. LOFAR, a state-of-the-art astronomical telescope, can map lighting on a meter-by-meter scale in three dimensions, and with a frame rate 200 times faster than previous instruments could achieve. "The LOFAR measurements are giving us the first really clear picture of what's happening inside the thunderstorm," said Dwyer.
It's OK . . . (Score:2)
Why the sky? (Score:2)
Why do we think it starts in the clouds? Why not the ground? An ionic pathway is setup between the two.
Perhaps someone familiar with the science can comment?
Re:Why the sky? (Score:4, Informative)
Because the cloud loses energy.
If it was coming from the ground, each lightning bolt should add energy to the cloud, and the storm should keep growing until it is no longer near the ground, for whatever reason. But it doesn't happen that way. Instead, the potential of the ground rapidly returns to its previous state, and the potential of the cloud is reduced. So clearly the cloud is the energy source.
You can either have a field effect and say that the concept of a "source" doesn't apply, or you can have something that starts at the energy source. So the cloud is the only candidate for a beginning.
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I'm not on board with the idea of the cloud being the source of energy. The energy is in the potential difference between cloud and ground. It's all relative. The lightening should lead to the potential difference reducing, but since we measure everything relative to ground, it appears in terms of the potential of the cloud reducing when really the potential of the system has reduced and entropy has increased. If you were a cloud dwelling being, you might view lightening as coming from the ground with the s
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Oh, did your feefies get hurt because an engineer schooled you about the stupid shit you heard somebody say, and repeated?
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Fun, but how do you then explain intra cloud, cloud to cloud,and/or cloud to air lightning?
I'm not explaining it. I'm no cloud scientist. I'm just asking a question based on the things I've learned along the way.
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I'm not on board with the idea of the cloud being the source of energy.
You're confusing electric current and electric charge.
It's all relative
No.
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I am not confusing charge with current. There's charge. Charge up there yields a field between here and there and so an electropotential. It drives a current when the lightening goes flashy flashy.
In what way is electric potential not a relative measure between two points? These things are all linked, by Maxwell's equations no less. If it was not relative, you multimeter would only need one probe lead instead of two.
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You're confused about what a charge is.
You're confused about the difference between electrostatic potential energy and electric potential.
Here is an easy lecture by Walter Lewin to understand it better. https://youtu.be/QpVxj3XrLgk [youtu.be]
You seem to think that the cloud can have any amount of charge. That it is only relative. The relative difference is important for lightning, but not for understanding where the energy is coming from. You use the relative difference to calculate voltage and current, but it is inco
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The best explanation with visual footage I have seen comes from Pecos Hank
https://youtu.be/JXhif3E3l2s [youtu.be]
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Thank you for that video, that was awesome!
Yo Grark
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In other video's he has he continues to talk about red sprites, blue jets and green ghosts, which are great phenomena that sometimes accompany lightning. Great visuals.
Mysteries create believers (Score:2)
we have religions centered around this thing, and we have no idea how it works,
Which is probably a requirement of everything that gives rise to a religion
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RTFP (Score:2)
We show that the first lightning source in the flash increases exponentially in intensity by two orders of magnitude in 15 microseconds, while propagating 88 meters away from the initiation location at a constant speed of 4.8 ± .1 x 10^6 m/s. A second source replaces the first source at the initiation location, and subsequent propagation of the lightning leader follows.
There is a perfectly good link to the preprint in both the original and this dupe.
Not the Plasma you are Assuming (Score:1)
Lightning Religion (Score:2)
"It's kind of embarrassing. It's the most energetic process on the planet, we have religions centered around this thing, and we have no idea how it works,"
This statement led me to wonder just what religion this guy is aware of that is based on a sound understanding of physics.