Sciencemadness Discussion Board - lightning storms

lightning storms

wg48 - 31-5-2018 at 01:33

There are probably going to be some lightning storms in my area today. I must confess I have an urge to set up a barrel of sand with a spike in it that is attached to a coil of fine wire that is attached to a firework rocket. Then wait until my built in electroscope (the hairs on my arms and the top of my head) indicates there is a strong electric charge above me to send the rocket in its direction. Flash bang and I have a fulgurite.

Perhaps a very long fine wire attached hydrogen balloon released in to the storm as it approaches would be fun too. I will probably just settle for storm chasing LOL

VSEPR_VOID - 31-5-2018 at 01:47

I like this idea, just make sure the sand is grounded. The balloon will not work because of the wind. The rocket seems like a better idea but there is still the wind and rain. The wire will not hold up to the current and it will vaporize the second lightning touches it. Your best option is to go with a really big pole attached to the top of a tree or house.

I think I recall that professionally this is done with tall metal poles on beaches.

Fulmen - 31-5-2018 at 02:15

A hair thin wire will do just fine. Sure it will vaporize in a microsecond, but the ionization path will conduct just the same.

The biggest challenge will be how to launch the rocket safely. A long fuse and running like h*ll could work, but it would still be a scary endeavor. Electric ignition will probably result in electrocution and/or a premature launch. Radio will also be fraught with problems during a lightning storm. A mechanical trigger using something completely non-conductive (perhaps fishing line) could work, but I would probably use electronic ignition with an air or fiber-optic control.

Air would probably be the simplest to jerry-rig. A plastic tube with a push button at the end and a small plunger should do the trick.

wg48 - 31-5-2018 at 03:33

Vsepr:

As fuman says the thin wire works most of the time. see: https://www.youtube.com/watch?v=34NpyA2OuaE

The baloon is released with the wire hanging below, only attached to the balloon. The idea is it shorts out a vertical section of air so it will be more likely to attract a strike as it drifts up.

It would be difficult not to have the barrel grounded wrt millions of volts. I spike from the ground into the bottom of the barrel would increase the chances of a good fulgurite.

Fulman:

Yes I would use pneumatics or fiber optics to trigger the rocket.

The storm is still a long way off

for a real time strike map https://www.lightningmaps.org/#x=;m=sat;r=0;t=2;s=0;o=0;b=0....

alternate (cheaper) conductors

barbs09 - 31-5-2018 at 03:46

Do you think cotton string soaked in a concentrated solution of sodium chloride might be conductive enough?

wg48 - 31-5-2018 at 04:15

Quote: Originally posted by barbs09

Do you think cotton string soaked in a concentrated solution of sodium chloride might be conductive enough?

Yes I do think it would be. Just damp string worked for Benjamin Franklin fortunately his kite was not struck but he did get spark to his knuckle. Other experimenters were not so lucky and were killed. (DO NOT TRY IT)

I think a very fine copper wire would be lighter than salty wet cotton and carbon fiber better yet.

See: https://en.wikipedia.org/wiki/Kite_experiment

[Edited on 31-5-2018 by wg48]

barbs09 - 31-5-2018 at 04:30

Yes wet string would be heavy and cohesive. Just googled fine copper wire. Cheap as chips! $6 for >900m of 0.07 mm wire.

http://giovannaimperia.com/metal/wire/extra-fine-copper-wire...

You would either have to lay it out / spool it out in big loops to ensure minimal tension in the wire during take off!!

Fulmen - 31-5-2018 at 12:33

Perhaps thin sewing thread coated with graphite could work?

unionised - 31-5-2018 at 12:50

Have you noticed that you typically get static shocks while wearing synthetic fibres, but not when wearing cotton?

Anything solid is a good enough conductor- all it has to do is conduct better than air.
It's possible that the trail of hot air + smoke left by a pyrotechnic rocket would be a good enough conductor to trigger the flash.

Don't try this near any power lines.

wg48 - 31-5-2018 at 23:45

Irritatingly Germany, Holland and France hogged most of the lightning probably a brexit effect LOL.

I cannot decide which is better attach the bobbin to the rocket or to the ground. Probably the bobbin on the ground requires less thrust for a given height if the air friction of pulling the long line through the air is not significant. In both cases you end up with a long line lifted in to the air but in the case of the bobbin on the rocket the whole bobbin is initially lifted while the line is pulled out so more thrust power is needed than the bobbin on the ground. Guided missiles using a fiber optic link have the bobbin on the missile and the fiber can be a hard to believe 60km long !!!, see https://www.army-technology.com/projects/polyphem/

I see the post about none conductive carbon fiber was deleted. Some posters know how to self correct fully.

LearnedAmateur - 1-6-2018 at 01:22

We had some good lightning over the past few days here to be fair, especially on Sunday evening and yesterday, although high up above the base cloud layers so only a few actual forks could be seen.

And yeah, should’ve done some more research before posting that, I’ve read articles about lightning strikes bringing down helicopters where composite components have literally exploded due to lightning where the resultant vibrations ruin the flight characteristics. I wrongly assumed that graphite/graphene was the only form of carbon which could conduct, but of course carbon fibre is composed of this. Always room for learning!

nitro-genes - 1-6-2018 at 12:27

Lightning rockets...amazing!

What are the odds of actually triggering a lightning strike and how do they know when to fire it? Can you measure voltage differentials or changes in electric field or so during a lightning storm? Even with the vastly decreased resistance compared to air alone, I reckon many rockets would be needed. The Empire State Building is struck only 23 times a year, so a timescale of few seconds in a year to fire your rocket. I guess location is everything.

Unfortunately, helium balloons are not usable in a storm. I wonder though...would something like a kite-helium-balloon-hydrid offer any advantages? Wonder if it would be possible to design a helium balloon in such a way as to act like a sail or kite. Maybe these could reach the height of a helium balloon while being stable in strong winds like a kite.

[Edited on 1-6-2018 by nitro-genes]

Vomaturge - 1-6-2018 at 14:57

I suppose it depends how high the rocket goes. Even those little model rockets can go 400, 500 meters. If you believe this video is real then adding some voltage to the wire helps create ionization around it. But I really don't see how 10-30kV would make such a difference when the natural potential due to the lightning is already so high. I think the vid's either fake, or the extra-xtra mad scientists who tried this just got lucky the second time, and destroyed a TV when they didn't need to. After all the crazy stuff they appear to have done, they're lucky not to be dead!

In any case, the fact that the Empire State Building is struck even that often shows how much of a difference a few hundred meters of altitude makes in this game. For this reason, a kite/balloon/rocket with a thin tether will work much better than a 20m pole that happens to be the tallest thing on the block. The pole will get lightning if it would have hit on the block anyhow, but the rocket will gather potential strikes which would have otherwise fallen anywhere in a much larger area. To tell when to fire the rocket, you could a) use an electric field meter (maybe an electroscope with a needle on top?) or b) time the average interval between lightning strikes during the storm (the time the cloud takes to charge), and launch a short while before the next strike is due to fall.

The idea of triggering lightning is amazing. It seems like it wouldn't be do-able, and yet has been done with pretty simple equipment. Have fun, and stay safe!

Twospoons - 1-6-2018 at 15:19

Quote: Originally posted by Vomaturge

But I really don't see how 10-30kV would make such a difference when the natural potential due to the lightning is already so high.

I worked in electric fencing for a couple of years, and I can tell you they are magnets for lightning strikes. Typical voltages were 8kVto 10kV (though a phenomenon called fence resonance could make it higher. We sold a special diverter kit to send the strike to ground, instead of it frying the insides of the fence energiser. Some of the energisers we got back for "repair" were basically a box full of copper plated char.

One issue with very thin copper wire is that its breaks very easily. If you can get it, thin nichrome wire is far stronger. I have a roll of hair thin nichrome, and its strong enough I don't try to break it by hand- pretty sure it would cut me first.

Mount your wire on the rocket - thats the way the military do it, and they will have good reasons. It needs to be spooled onto a cone so it can be pulled off the end, much the same way industrial sewing machine thread is spooled.

[Edited on 1-6-2018 by Twospoons]

wg48 - 2-6-2018 at 03:47

Apparently typical lightning strikes originate from the cloud at between 15km to 25km height. Lets say 20km, so to have a significant chance of initiating a strike to a wire connected to ground the wire would have to reduce that distance by say 10%. That means the wire would have to be 2km long. There would have to be a cloud charging up and almost ready to create the strike. I will assume a 1km wire to have a reasonable chance.

40awg wire (0.08mm dia) is 0.03lbs per 1000ft that’s 13.6g per 305m. Say 50g for 1000m. Assuming the bobbin is mounted on the rocket I think that’s liftable for a medium sized firework rocket.

Perhaps a cheap drone could be used. That would have the advantage of staying up much longer and hence have a greater chance of initiating a strike. of cause you still need to be under the thunder storm.

Any members in central Florida LOL ?

Yes 40awg copper wire will be very weak.

barbs09 - 2-6-2018 at 05:59

I don't think you would necessarily need to reach the clouds to initiate a bolt. A good storm will have already set up a strong enough potential gradient between the earth and the clouds, that your copper line just needs to spray a few electrons at an altitude much higher than anything else around it. It would ave to be well earthed though.

When a tree gets struck, it doesn't need to be 20km high. As stated above, an additional 15-20kv may just initiate something that was likely to occur anyway.

A kite could get pretty high during the sorts of winds associated with localised storm cells..... As long as it's an efficient kite and generates plenty of lift, it should get plenty of height. The more gradual lift, relative to a rocket, would not put too much strain on a fine copper wire if it is somehow led out with strong nylon line.

Tsjerk - 29-11-2018 at 10:16

no source unfortunately.

Attachment: rocket.mp4 (85kB)
This file has been downloaded 599 times

[Edited on 29-11-2018 by Tsjerk]