What-If 0016: "Lightning"

[Quicksilver]

http://what-if.xkcd.com/16/

I am not an authority on lightning safety. I am a guy who draws pictures on the internet. I like when things catch fire and explode, which means I do not have your best interests in mind. The authorities on lightning safety are the folks at the US National Weather Service:

Comforting. This one is way too vague, it only says what the dangerous part of the scenario is, without fully explaining the danger.

[Klear]

So... can anybody explain what is a submarine safe?

[ElWanderer]

So... can anybody explain what is a submarine safe?

A safe (where you might hide your money, gold and incriminating documents) that is underwater?

[rhomboidal]

With my luck, I'd escape the lightning only to get steamrolled by a 60-meter sphere.

[Klear]

So... can anybody explain what is a submarine safe?

A safe (where you might hide your money, gold and incriminating documents) that is underwater?

Isn't that a safe in a submarine? Which we are expressly told not to confuse with a submarine safe?

[dalcde]

Perhaps submarine safe means 'as safe as a submarine'?
http://www.urbandictionary.com/define.php?term=submarine%20safe

['); DROP TABLE users;]

So... can anybody explain what is a submarine safe?

A safe (where you might hide your money, gold and incriminating documents) that is underwater?

Isn't that a safe in a submarine?

No.

[ElWanderer]

So... can anybody explain what is a submarine safe?

A safe (where you might hide your money, gold and incriminating documents) that is underwater?

Isn't that a safe in a submarine? Which we are expressly told not to confuse with a submarine safe?

No.

Submarine as a description can mean either "relating to a submarine (a watercraft capable of independent operation underwater)" or "underwater". It can be unclear from context which one applies e.g. is Dr Evil's Submarine Base a surface facility where his evil submarines dock, or an underwater supervillian headquarters? But in this case we've been told not to consider "relating to a submarine", leaving the underwater option.

You can create a submarine safe by dropping a safe into a body of water. Sounds a bit like security through obscurity, and liable to damage the contents of the safe... better to base your safe in a safe*, submarine base.

* i.e. with airlocks, guards etc.

[Klear]

Submarine as a description can mean either "relating to a submarine (a watercraft capable of independent operation underwater)" or "underwater". It can be unclear from context which one applies e.g. is Dr Evil's Submarine Base a surface facility where his evil submarines dock, or an underwater supervillian headquarters? But in this case we've been told not to consider "relating to a submarine", leaving the underwater option.

You can create a submarine safe by dropping a safe into a body of water. Sounds a bit like security through obscurity, and liable to damage the contents of the safe... better to base your safe in a safe*, submarine base.

* i.e. with airlocks, guards etc.

Oh! Thanks, that's what I was missing. I don't think I heard the word "submarine" used like this, only "underwater". Or rather, I probably did, but misinterpreted it every time.

[solune]

I'd like to make a distinction between submarine - "under the sea" and subaquatic - "under water".
I doesn't help in any way but I feel better by saying it.

[mathmannix]

I would like to propose another definition for submarine:
(adj.) describing anything (or anyone) physically beneath a Marine (a person serving in the United States Marine Corps, UK's Royal Marines, or any other country's equivalent or approximately equivalent service branch).
A submarine safe could, therefore, be a safe under a marine's bunk. Which, I think, would make it reasonably safe.

I would also like to state that urban dictionary seriously freaks me out, where every word apparently is some kind of sex act. (I'm looking at you, submarine safe, as well as specifically the next article that showed up under it.)

[endolith]

Oh! Thanks, that's what I was missing. I don't think I heard the word "submarine" used like this, only "underwater". Or rather, I probably did, but misinterpreted it every time.

The noun "submarine" is an abbreviation of the adjective+noun "submarine boat".

The leader carries comparatively little current—on the order of 200 amps.

...because the air between the cloud and ground is not conductive yet, so the current exists as a corona discharge of ions traveling through the normal insulating air? The glowing streamer is fully-conductive plasma, but until it reaches the ground and completes the circuit, there's still non-conductive air that the ions have to pass through, in the same way that an ionocraft produces thrust? Cool.

http://amasci.com/tesla/spark.html

[mikaey]

I think he forgot to answer the question of "what if you were in an airplane".

Airplanes are actually quite safe from lightning. Airplanes regularly do get struck by lightning -- commercial airliners get hit, on average, about once a year (USAToday actually has a nice article on it) -- but these days, they're designed to be able to handle them without issue. The lightning flows around the aluminum exterior of the plane and out of the bottom. If you're on the airplane, you might see the flash, but that's about it -- the plane would continue merrily on its way to Nashville, regardless of whether you wanted to go there or not.

[Max™]

^Bad sign.

[Kaden]

This one is way too vague, it only says what the dangerous part of the scenario is, without fully explaining the danger.

Umm... I think the danger is that if you get struck by lightning, you're probably going to die.

I had an algebra teacher who had been struck by lightning twice in his life- once in a locker room shower and once in his home shower. He was also missing the tips of 3 fingers due to a chainsaw accident, and since there was visible evidence of that, we had to believe him about the lightning, too. But he was an awesome teacher, so we would've believed him anyway.

[backoffbro]

So uhh... there was a 15 foot tall man? Or was this some crack at the Dinosaur Comic artist? Kind of a stretchy one.

[flicky1991]

So uhh... there was a 15 foot tall man? Or was this some crack at the Dinosaur Comic artist? Kind of a stretchy one.

Yes, the Dinosaur Comics artist. You've just stated the reason why it's funny...

[Dazzle]

Hey,

Long time lurker first time poster but this what if has compelled me to register

I live and work on a boat, a carbon boat with a 60 meter carbon mast on it in fact and the lightning conversation comes up alot!

On my last boat we were caught in a pretty bad thunder storm off of Italy. I was on deck stood in a puddle of rain water and the lightning was blinding if not for the rain but we didnt get hit. My friend who worked on an identical boat however has been hit by lightning on that boat 3 times (the boat not him!) and each time the "damage" was different from blowing all the electrics (litterally instrument displays exploded) to blowing a single lightbulb.

Another friend was struck by lightning, stood by the mast the rest of the crew watched while a flash went from the mast to his hand and out the other hand to the guard wires. He escaped unscathed but a guy with a metal plate in his leg sat below went to hospital. I have also heard stories of people getting a shock from lightning hitting the water nearby.

There is no shortage of gimmicks to help and some people even hoist there anchor chain up the rig and dangle it in the water to give the electricity a clear path to earth (and some say this is making you more likely to get hit in the first place) but nobody seems to be able to say how or why one boat is more susceptible than another other than blind luck!

I hope it will never happen, my brother in laws friend was one of the near a tree statistics several years ago, the real danger for a lightning strike for us is any subsequent electrical fire that could occur, sinking (lightning strikes have been known to blow a hole in the hull of a boat if that is a shorter path to earth than the keel and then getting the boat to port as quickly and safely as possible!

[yellow103]

Maybe a submarine safe is a safe for submarines.

[Jackpot777]

If you're on the airplane, you might see the flash, but that's about it -- the plane would continue merrily on its way to Nashville, regardless of whether you wanted to go there or not.

You. I like you.

[MatatTHC]

All the water related sub-questions seem to get much more interesting if they are reconsider in an evolutionary context. I think it might be entertaining to think a bit more about it. So - my point is the following:

Why are there still ducks and fishes around if a lighning is dangerous for objects on the water surface?

For instance, if each lake is hit once during the lifetime of a duck then there should be no ducks. But maybe there are refugiums, i.e. lakes smaller than 60m surrounded by high mountains .

[Max™]

Lightning won't kill everything in the water, it isn't like tv where you drop a wire into water and everything dies, it just makes certain paths more favorable than others. Paths which go through living things are often favorable, but not a path which goes through EVERY living thing in a body of water.

As for Nashville, the woman knew someone online who used the screen name "God_help_me_Im_in_Chattanooga", which I think is hilarious.

[YpsilonOmega]

If you're on the airplane, you might see the flash, but that's about it -- the plane would continue merrily on its way to Nashville, regardless of whether you wanted to go there or not.

There is quite some truth in this...

This summer I was on a flight from Tallinn to Hannover and the plane was hit by a lightning just a few minutes after the takeoff, while it was rising through the clouds. When is reached its travelling height, the pilot said that "all systems are fully operationable" and we can continue our flight to Hannover without worries. 15 minutes later he turned around and told us that after talking to the ground crew he got orders to return to Tallinn, because the aircraft needs to be fully checked before the next takeoff. And since I was flying with Estonian Air and they don't have a full technical crew in Hannover, they had to do it in Tallinn. About one hour after the takeoff we were on the ground again, and it took another two hours to check everything before we could take off again.

But apart from that is was just very beautiful to see a lighning from nearby. It was not as bright as I expected (that's why I wasn't sure whether it actually hit the plane, unless the pilot confirmed it - they said they could even see a small spot where it hit the plane and burned some paint during the checkup on the ground) and also not very loud, but my perception of the noise was probably reduced by the pressure on my ears.

[wannes]

Is it just me, or does one of the "leaders" in the video makes a loop with himself? Surely looks like that. at 00:06-00:07 in the video somewhere in the middle of the screen, first it moves up then goes back to the left and goes back on his own path. COOL

[JJH]

Maybe a submarine safe is a safe for submarines.

That would be a submarine pen. Or is a pen that is submarine?

[arnoldus]

Regarding the bullet.
It is my understanding that there would be a refraction happening (just as when a light ray changes angle when hitting a medium of different density) when the bullet travels into the bolt.
The bolt changes the pressure (and I would think temperature) of the path it travels through (which is what causes the sound of the crack).
When the bullet goes into this different medium (highly different pressure and temperature), it should experience a deflection.

[Harikawashi]

Last year, I was a passenger on a light 8 seater turbo prop plane flying from Eenhana to Windhoek.
We had to fly through a thunderstorm and the plane was hit by lightning. The flash was significant, the thunder was VERY LOUD, and it took out all the plane's electronics except the GPS. I was pretty sure I was going to die.
The two pilots had to get out of the clouds using sight only (no weather radar), and when we got to Windhoek, they could not radio the control tower to clear for landing. They ended up activating some emergency radar beacon or something, that basically tells the tower "We have no radio, and we're coming in to land, so clear the runway for us." We circled around and landed without incident. Back on the ground, we could see the two burnmarks on the plane, one on the nose and one on the tail. Not something I want to repeat!

Here are two pics of the burn mark on the nose, right on one of the screws of the cover plate:
https://dl.dropbox.com/u/38362550/Perma ... umPic1.JPG
https://dl.dropbox.com/u/38362550/Perma ... umPic2.JPG

[Max™]

Is it just me, or does one of the "leaders" in the video makes a loop with himself? Surely looks like that. at 00:06-00:07 in the video somewhere in the middle of the screen, first it moves up then goes back to the left and goes back on his own path. COOL

Indeed.

[jay35]

Almost looks like one of those old Tank Wars Scorched Earth (or maybe Pocket Tanks?) weapon visual effects.

[J Thomas]

Is it just me, or does one of the "leaders" in the video makes a loop with himself? Surely looks like that. at 00:06-00:07 in the video somewhere in the middle of the screen, first it moves up then goes back to the left and goes back on his own path. COOL

2D projection. It could be doing that, but maybe not.

[ijuin]

I think he forgot to answer the question of "what if you were in an airplane".

Airplanes are actually quite safe from lightning. Airplanes regularly do get struck by lightning -- commercial airliners get hit, on average, about once a year (USAToday actually has a nice article on it) -- but these days, they're designed to be able to handle them without issue. The lightning flows around the aluminum exterior of the plane and out of the bottom. If you're on the airplane, you might see the flash, but that's about it -- the plane would continue merrily on its way to Nashville, regardless of whether you wanted to go there or not.

An airplane with a conductive skin (usually aluminum or titanium), or one with a mesh of wires underneath a non-conductive skin (such as with the 787) forms an imperfect Faraday cage around its contents, which protects the contents as long as said contents are reasonably insulated from the skin/wires.

[YpsilonOmega]

I'm not an expert on this, but I think one of the main problems when a lightning hits a plane is the rapidly increasing magnetic field of its current. This may induce some high voltage in other parts of the plane and cause failures of electronic systems. And I guess these are a lot more dangerous than someone using a mobile phone... Just look a few posts above of this one.

[Fire Brns]

I've seen enough lightning in real time living in Florida to say As long as you aren't tempting the fates you should be safe from lighting. The tallest thing around is usually a tree or a building.
Randal doesn't emphasize this quite enough: do not stand under trees during lightning storms, very few people are killed by lightning because we usually go indoors when it rains but for every other animal during lightning storms the death rates are far higher. Lightning and aliens are basically the only 2 methods for ranchers to loose large numbers of cattle in an short period of time. Electricity can also arc back out the underside of the leaf canopy and directly into anything under the tree.
Running in a lightning storm, the amount of friction you generate that would increase your general static is outweighed by the reduced time it takes to get indoors. (Assuming you are running for a shelter)
Carrying fishing poles, yes, terrible but the only reason you would be carrying one is because you are trying to get off your uncovered boat to a shelter.

As for the submarine boat that people are asking about, most are traveling in salt water which behaves differently than fresh water with electricity. The energy would quickly dissipate thanks to the conductivity of salt. Now let's say you are in fresh water: for a modern submarine, they are insulated by so completely inert unless someone left a hatch open. I only know they were insulated because cookie cutter sharks kept mistaking them for whales.

[Klear]

Isn't it more likely to get killed by a falling branch if standing under a tree? (which can happen even if the tree isn't struck by a lightning).

[Fire Brns]

Isn't it more likely to get killed by a falling branch if standing under a tree? (which can happen even if the tree isn't struck by a lightning).

Deadfalls? It depends on the branch, Usually large dead branches on a live tree are only large enough to give a concussion or or break a bone and most are only bad enough to give you an odd set of cuts. Under a dead tree the whole game has changed. But if you've ever been hit by an acorn, walnut, or pine cone you know those suckers hurt. In my close to 14 years of camping with scouting organizatuions we have only ever observed a tree fall in the woods once.

[tomintx]

...
I live and work on a boat, a carbon boat with a 60 meter carbon mast on it in fact and the lightning conversation comes up alot!
...

As a wee lad in the 70's,I had a number of personal experiences with lightning and sailboats. My family had a sailboat business.

1) I just happened to be looking out a window during a storm when lightning struck a nearby boat. The lightning struck the 45 foot tall aluminum mast. For several seconds afterwards, there was a puff of green smoke in the exact shape of a fiberglass radio antenna which had been a part of the mast, until the lightning converted it to smoke. The people on board the boat were not affected, nor were their electronics. The boat had a copper plate under water which was electrically connected to the rig with heavy gauge wires.

2) Not long after, I encountered another boat, where the owner had not opted to purchase the "lightning ground option." This boat had also been struck by lightning while unoccupied. When we saw the boat, it looked like it was sitting a little low in the water. We decided to investigate and found evidence that a fire had been in the boat, and that it was slowly filling with water. Further investigation revealed something like 3,000 little pin-holes thru the fiberglass hull where the lightning had exited. I think the boat was declared a total loss by the owner's insurance company.

Ground the rig. Lightning's going to go where it wants. You might want to offer it a path that helps it to find the ground.

[mathmannix]

Isn't it more likely to get killed by a falling branch if standing under a tree? (which can happen even if the tree isn't struck by a lightning).

Deadfalls? It depends on the branch, Usually large dead branches on a live tree are only large enough to give a concussion or or break a bone and most are only bad enough to give you an odd set of cuts. Under a dead tree the whole game has changed. But if you've ever been hit by an acorn, walnut, or pine cone you know those suckers hurt. In my close to 14 years of camping with scouting organizatuions we have only ever observed a tree fall in the woods once.

Was it observed audibly, or merely visually?

[tomintx]

Is it just me, or does one of the "leaders" in the video makes a loop with himself? Surely looks like that. at 00:06-00:07 in the video somewhere in the middle of the screen, first it moves up then goes back to the left and goes back on his own path. COOL

Probably not. Consider that the image is a 2D view of a lightning bolt that likely occurred in a 3D space (the atmosphere). Consider that the leaders which appeared to have folded back onto the main branch were probably headed right towards the camera person.

If you're not careful, it might jump out of your screen and zap you in your chair.

[Klear]

In my close to 14 years of camping with scouting organizatuions we have only ever observed a tree fall in the woods once.

Your observation probably ruined it but still: did it make a sound?

[adaviel]

I found the source of the lightnng video:
http://www.weathervideohd.tv/detail/1091/cumulonimbus-cloud-to-ground-cg-stepped-leaders-overcast-continuing-current-m-components-rain-falling-clouds-primary-types-lightning-sky-moods-tornadoes-hail-downbursts

For $200 you can buy this at 1920x1080

Location: South Dakota
Single Stroke CG in High Speed
Concept: High speed video reveals lightning structure
A myriad of stepped leaders work their way towards ground, with one meeting an upward streamer to produce a brilliant return stroke, followed by continuing current and possible m-components. Captured using a high speed camera running at 7200 fps. Uprezed to HD. Video Credit: Tom A. Warner
Asset ID: 1091