Detailed footage reveals what triggers lightning | Hacker News Reader

Detailed footage reveals what triggers lightning

quantamagazine.org

193 pointsprivong26 comments

Pretty neat overall. I thought this was an interesting random fact:

> The key role of ice crystals dovetails with recent findings that lightning activity dropped by more than 10% during the first three months of the COVID-19 pandemic. Researchers attribute this drop to lockdowns, which led to fewer pollutants in the air, and thus fewer nucleation sites for ice crystals.

I just love how perfectly this squeaks more science out of an existing investment with seemingly no ill effect on its intended use. I imagine there will be lightning studies out of this observatory for decades.

is this still the case when you get lightning triggered from large amounts of smoke in wild fires? i’ve seen footage of fires in australia where the smoke becomes so big it starts to cause it’s own lightning

Or volcano ash: https://volcanoes.usgs.gov/volcanic_ash/lightning.html

That seems to track; pyrocumulonimbus clouds happen when smoke mixes with cooler air high up. The soot and smoke could provide the nucleation sites the article talks about that promote ice crystal growth.

Makes me remember when the CIA considered using lightning as a killing weapon...maybe they're watching closely now

I guess that would be pretty useless, because you would have to catch your target in open field, during the thunderstorm, which is highly unlikely, since most people hide from it. Targeting a car could be solution, but even then, if the victim has their seat belts on they would probably survive the crash.

Given a sufficient budget and time, I think this could be made to work, on a clear day. How? Nitrogen lasers in low earth orbit target the upper end of the atmosphere in a volume over the target as the satellite approaches the target then at azimuth fire a larger pulse directly at the target, ionizing a channel all the way from the top of exosphere to ground, grounding the collected charge from the now conductive volume, to the target.

The clickbait headline belies the content of the article: researchers still don’t know exactly what triggers lightning.

Personally I find the leading hypothesis a bit absurd or at least unbelievable. The idea that colliding ice crystals shed electrons and form ionized air in masses great enough to trigger the most energetic phenomenon on the plant seems … like a Newtonian hammer looking for a nail.

It’s well known that the sun emits a powerful electric field which causes the “northern lights” to appear at the poles of the planet. And it’s well known that solar activity is correlated with large scale weather patterns and atmospheric thermodynamics.

How is the Sun not a viable explanation for the origin of lightning? Cosmic rays initiating an electron cascade is interesting, but I would expect the sun to play a bigger role than that.

They did say that it was the leading hypothesis that this puts aside.

The auroras aren't caused by the Sun's electric field impinging on the Earth, they're caused by actual charged particles from the solar wind entering the atmosphere and ionising air molecules.

Lightning isn't that energetic. A 16 MW wind turbine can capture the energy of a lightning bolt from thin air in about 1 minute.

The average lightning bolt that strikes the ground contains about 1 billion joules of energy. That's 1 GJ of energy.

The Siemens Gamesa’s SG 14-222 DD wind turbine has a capacity of 14 MW. In 71 seconds that wind turbine would capture the energy of a lightning bolt.

There is an enormous amount of energy in the air moving around us. I can very well believe how that movement can charge up lighting.

With an average duration of 0.2 seconds, a bolt of lightning therefore has like 355 times the energy of your wind turbine for the same length of time.

Sounds fairly energetic to me.

> Sounds fairly energetic to me.

Sounds fairly powerful to me.

If you assume that it takes a while to build up for a sudden discharge, that doesn't sound like that much to me.

Also we don't know how much atmosphere-volume per second is needed for 1 "normal" lightning strike. (Assuming some sort of volume-based cause.)

In contrast, the amount of air passing through the blades of a turbine per second is probably much easier to calculate, and I'd wager less.

You're mixing energy and power.

Have you ever seen a thunderstorm averaging five lightnings per second? I haven't. But I have seen plenty with a couple lightnings per minute - right in the ballpark of the power of a small wind farm beneath.

For the curious: https://en.wikipedia.org/wiki/Catatumbo_lightning:

“Catatumbo lightning (Spanish: Relámpago del Catatumbo) is an atmospheric phenomenon that occurs over the mouth of the Catatumbo River where it empties into Lake Maracaibo in Venezuela. It originates from a mass of storm clouds at an altitude of more than 1 km, and occurs during 140 to 160 nights a year, nine hours per day, and from 16 to 40 times per minute”

That seems to be the most one gets on earth, but there, it isn’t rare.

I've seen a couple with a bolt every couple seconds. More or less continuous lightning.

Back in 2017 there was a superstorm over the UK and France. Here in London the lightning was basically continuous. It was really bizarre because it looked like someone had put stadium lights on so the whole sky was lit up continuously.

Apparently there was something in the region of 120,000 lightning strikes over 12 hours, which is 10,000 per hour. That was, of course, spread over a large region, but still...

https://metro.co.uk/2017/07/19/londons-epic-thunder-and-ligh...

https://strangesounds.org/2017/05/120000-lightning-strikes-e...

Yes. I once drove through a storm which lasted well over an hour, with continuous fork and sheet lightning around the entire horizon. An absolutely fantastic sight, never seen such a dramatic spectacle before or since, it was absolutely stunning.

New Mexico fall thunderstorms can do one every 2-3 seconds for a minute. And the storm itself will last for hours, even though it calms down a little. Lightning radar apps show a 30 minute window of lightning and can fill up areas of the map with just solid yellow from the overlapping bolt icons.

Yeah and a huge rock you roll up a mountain will fall with huge force in a few seconds, it doesn’t mean it has any more energy than what was used for elevating it.

How does sun send its electric energy to a 70m wide region of the cloud? Aurora borealis is 80-1000km across.

Last summer, we walk half way around the LOFAR superterp and along some other LOFAR stations in the area. It is in a rather quiet nature reserve. I recognized the roads we walked in the back ground of the animation, which is from a point in the sky looking down towards earth.

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