Static Buildup/Discharge within Funnels?

[Kirk Chestnut]

Power flashes and lightning aside, has anyone ever observed static discharge or flashes within the base of a funnel? It's fascinating to read of historical observations, prior to electrification, where flashes of colored lights, St. Elmos Fire, etc. were seen from within a funnel. Obviously the funnel provides a path for a cloud to ground discharge but what about static discharge at the base? I've never seen this anomoly on video. I know years ago farmers would tune to TV Ch. 2 and watch for an increase in the luminence level of the static if a tornado was near.

 

[rdale]

Obviously the funnel provides a path for a cloud to ground discharge

I'm missing that - what is obvious?

 

[Jeff Duda]

It's fascinating to read of historical observations, prior to electrification, where flashes of colored lights, St. Elmos Fire, etc. were seen from within a funnel. Obviously the funnel provides a path for a cloud to ground discharge but what about static discharge at the base? I've never seen this anomoly on video. I know years ago farmers would tune to TV Ch. 2 and watch for an increase in the luminence level of the static if a tornado was near.

Aside from hearing the term "funnel-center lightning" in a commercial about a tornado video back in the 90s, I really have no idea what you're talking about. It would be nice if you could share some of these historical observations to which you are referring.

I did a Google Scholar search on "static electricity in tornadoes" and found one article that may have something to do with your question. The paper is over 50 years old, though, and as far as I'm aware, no one is currently performing any research on the subject. You'll have to shell out some dough to read it, but the link is here: http://onlinelibrary.wiley.com/doi/...sCustomisedMessage=&userIsAuthenticated=false

 

[Jason Harris]

Some of Dr. Bernard Vonnegut's theories on tornado electricity pop up here too:

(news article) http://news.google.com/newspapers?n...P3E0AAAAIBAJ&sjid=_ckEAAAAIBAJ&pg=641,1967002

(some sort of website duplicating a print study of plasma/UFOS? "
Chapter 7 Atmospheric Electricity and Plasma Interpretations of UFOs" byMartin D. Altschuler
): http://files.ncas.org/condon/text/s6chap07.htm#s10
__
From radio emissions (spherics), it is estimated that about 20 lightning flashes occur each second in a tornado cloud. Assuming 20 coulombs per lightning discharge, the average current flowing through a tornado is about 400 amperes. Magnetic field measurements near a tornado indicate that such a current is not unreasonable. Using 109 joules per lightning flash, we find 2x1010 watts for the electrical power generated by a tornado.

Such estimates may be too conservative. Tornado lightning is reported to be brighter, bluer, and more intense than its thunderstorm counterpart

 

[rdale]

about 20 lightning flashes occur each second in a tornado cloud[...]
Such estimates may be too conservative. Tornado lightning is reported to be brighter, bluer, and more intense than its thunderstorm counterpart

Just so I follow... When I watch a minute long tornado video, I should be seeing 1200 lightning flashes and these flashes are brighter than typical lightning strikes? Because I'm not seeing that.

 

[TrumanBoyer]

I'm missing that - what is obvious?

Air is a strong electrical insulator. It requires approx 100,000 Volts to arc across 1" of air.

Air saturated with water Vapor is an even better insulator (sounds strange, but true).
-- part of the reason you don't get so many carpet shocks in the summer.

Under a storm base, the saturated air is a barrier to any current that might want to form
between the cloud base and the ground.

A string of Liquid water droplets, like in a cloud or a rainshaft, provides an "obvious" path
that electricity can arc across.

"Obvious" if you have studied thunderstorm electricity in detail, I suppose. -
(I'm not trying to sound snobbish here.)

Even in the case of a funnel cloud, where the condensed liquid water droplets might be traveling
upward, the speed of the electric current makes the UVV of the droplets insignificant.

My 2 cents...

There is an old account of a farmer unable to close a storm cellar door that tells of a tornado
hopping over his house, barn and cellar, and he gets a view straight up into the funnel.

The farmer gets so many details correct, like subvortices, and a pendant cloud in the center of funnel,
--all of this before Fujita's vortex studies --
that it makes it hard to discredit his observation that
"the inside was filled with lightning zig-zagging across" (or something like that)

I don't know if the account is online anywhere, (I will try to find it if anyone wants to read it)
but I think it came from a 1960 article in Nature magazine. I remember because I searched
for it for nearly a day in a University library (in 1986).

The 1960 article was about a theory that proposed that Thunderstorm Electricity is a factor
in Tornado formation, or at least a factor in stabilizing the vortex after formation. It actually
makes some sense, but now we know a lot more about genesis, and the electric field plays
a much less important role than the author asserts.

We do know that dust devils generate a rather strong electric field.

NASA and NOAA have done studies finding that there is some correlation between lightning
frequency and tornado formation. It seems that net lightning activity slows while a tornado is
present, presumably because the tornado allows the cloud's electricity to ground itself
without so much arcing. BUT MORE RESEARCH WAS NEEDED.

Anyway, this is something I am very interested in, and if anybody has anything to add, please
do so.

Thanks for listening, -T

 

[rdale]

"Obvious" if you have studied thunderstorm electricity in detail, I suppose.

I haven't, so that's why I'm asking. I really don't see this frequent lightning on any tornado (sighted or recorded.) If these strikes are occurring 20 times per second through the funnel, would it be obvious in real ways other than theoretical?

 

[Jeff Duda]

A string of Liquid water droplets, like in a cloud or a rainshaft, provides an "obvious" path
that electricity can arc across.

"Obvious" if you have studied thunderstorm electricity in detail, I suppose. -
(I'm not trying to sound snobbish here.)

I disagree that this is "obvious" even for someone who has studied basic electicity in a physics class. Also, have you seen the episode of Mythbusters where they test the idea that urinating on an electric rail will get you electrocuted? This youtube video shows the test: https://www.youtube.com/watch?v=pDY-0ijiOEQ

I'm aware that the scientific methods performed by the Mythbusers are about as legitimate as some of the chasers currently roaming the plains with all their gear claiming to be doing research for science and saving lives (read: not very legitimate), but they do make a point. While the number concentration of cloud drops that constitute a fully condensed tornado funnel (per unit volume) may be quite high (although I have yet to see any measurements, but obviously can be high enough to make the funnel visually opaque), that doesn't mean the distance between cloud drops is necessarily small enough so that the amount of electromotive force within the tornado is strong enough to drive a current across the arcs between them all the way to the ground. Let's check this using a back-of-the envelope calculation:
-The very largest of cloud drops are typically on the order of 100 microns in diameter (10^-4 m). The average size is probably closer to 10 microns, but let's see what happens with the biggest ones.
-The largest cloud drop number concentrations I've ever seen out of a 4 km model using double-moment microphysics was about 10^8 m^-3. NOTE: a 4 km model cannot resolve even a large tornado. Therefore, it is possible, if not likely, that larger number concentrations could be found in much finer models that are capable of resolving tornadoes. However, I'm not sure you'd find values more than another order of magnitude larger.
-Assuming cloud drops are spherical (they pretty much are), then 10^8 drops occupies 5.24 x 10^-5 cu m of space within 1 cu m of air (i.e., about 0.001% of the space in the 1 cu meter box is actually liquid water).
-Assuming that on average, the drops are as scattered as they can be (i.e, equally spread out), then you can fit about QUBIC ROOT(10^8) ~= 464 drops along a 1D 1 meter strip. That means you'd have one drop every 2.1 mm. That's 20 times the size of the average cloud drop. That means there's about 2.0 mm of space between cloud drops. According to the 100000 V per 1" rule, you'd need about 7900 V between each pair in a string of cloud drops to get the arc needed. I really don't know how strong a gradient in electric potential can build up in a tornado, but I'm skeptical that it can reach those levels anywhere off the ground (I think the friction between the winds, what debris there might be, and the ground, could probably generate quite a bit of static electricity).

Furthermore, as Rob Dale pointed out, there are TONS of tornado videos out there that do not feature any anomalous or unusual amount of lightning within the funnel. Also, given how close some chasers get to fully condensed tornadoes and how loud the thunder produced by lightning, especially at close range, is, I have a hard time believing there is that much lightning activity within that kind of tornado since no one who gets that close tends to report it. I'm not saying I think there is no lightning in a tornado (there might be some), but I am saying I don't think there is much.

 

[Mike Johnston]

That account of the farmer seeing up inside the vortex, that Truman cited, sounds very similar to a story in Snowden Flora's old book on Tornadoes of the United States. Maybe that's where it was originally reported. His description of the sub-vortices was something along the lines of "like hissing, writhing snakes" and also the lightning inside the tornado sounds familiar.

I believe some of the old-timer's first hand accounts have some accurate information. After all, there's no particular reason to doubt what they witnessed. And, although Flora's book had some fantastic, colorful stories, it seems like he was pretty meticulous in his research.

As to lightning in tornadoes, my simple take is that when the tremendous energy in a storm is concentrated in a local area like a tornado, incredible things can occur and electrical discharges could very well be part of that - maybe not all of the time, but sometimes.





'

 

[mikedeason]

Here's the original account from the May 1930, Monthly Weather Review:

http://docs.lib.noaa.gov/rescue/mwr/058/mwr-058-05-0205.pdf

 

[Stephen Levine]

What comes to mind is the twin tornado night time photo taken during the early Spring 1965 (Easter?) upper Midwest outbreak. I believe the photo was taken from near Toledo OH. Filmed from a back yard, both funnel clouds were fully lit, top to bottom. Has it been clearly determined what was causing the light? Was it static electricity? Internal glow from some other source, or reflection from ground lights?

 

[James Gustina]

Aside from hearing the term "funnel-center lightning" in a commercial about a tornado video back in the 90s, I really have no idea what you're talking about. It would be nice if you could share some of these historical observations to which you are referring.

If you have a copy of "Storm Kings" by Lee Sandlin nearby I'd recommend perusing it when you get the chance. A lot of "electric currents/lightning discharges with the funnel" accounts come up in there as well as some of the amazingly stupid theories of the time. I'd imagine most of these observations, for lack of a better term, came while people were in full panic mode meaning they were probably less than accurate i.e. a flash of lightning when a tornado is near equals the tornado is spitting out lightning or the tornado being tinted red by a setting sun is the tornado emitting a glow.

As for the farmer who saw up a tornado, I believe everyone is referring to the farmer outside of Greensburg? http://www.history.noaa.gov/stories_tales/inside_tornado.html

Edit: Another fun little tidbit bit from Finley's tornado paper that refers to electric discharge in funnels: http://www.lib.noaa.gov/noaainfo/heritage/tornado3.html

 

[TrumanBoyer]

If you have a copy of "Storm Kings" by Lee Sandlin nearby I'd recommend perusing it when you get the chance. A lot of "electric currents/lightning discharges with the funnel" accounts come up in there as well as some of the amazingly stupid theories of the time. I'd imagine most of these observations, for lack of a better term, came while people were in full panic mode meaning they were probably less than accurate i.e. a flash of lightning when a tornado is near equals the tornado is spitting out lightning or the tornado being tinted red by a setting sun is the tornado emitting a glow.

As for the farmer who saw up a tornado, I believe everyone is referring to the farmer outside of Greensburg? http://www.history.noaa.gov/stories_tales/inside_tornado.html

"Storm Kings" is well worth the time.

I saw it at a local library, and read the book in 2 sittings.


Thanks to all for the input, and I knew this would stir up a lot of impassioned debate.
It always does.


As for the funnel being an "Obvious" path...
I think it would obviously be a path of least resistance, in the absence of rain nearby.
(Rain droplets can carry much more net charge to the ground than lightning does anyway...)

Mythbusters ? That was one of my favorite episodes, very funny, but a pretty good experiment, actually.


The Third Rail example is in MY HUMBLE OPINION not well suited for application to atmospheric electricity.
3rd Rails are limited to about 1500 V (for insulation reasons), but with relatively High Amperage.
In a T-storm Voltages reach gigavolts, while amps "only" reach into the 100 kA range
-- we are clearly talking about an extreme potential for arcing --

If I remember correctly MythBusters did 2 takes on the 3rd Rail, with different results anyway.

Anyway if you think that they busted the myth, I invite you to try wizzing on an electric fence.
IT IS DO-able, but you have to carefully empty yourself, in short controlled bursts.
I once collected on a $20 buck wager using this technique.

This kind of debate over reports of observed phenomena - with only anecdotal evidence -
often degrades into a p*ssing contest about whose credentials make them better qualified
to evaluate their validity.

THANKS for not going that route, guys.

Some of what follows will be disjoint, but I don't feel like writing a novel right now.

More fuel for debate... some more thoughts and factoids...

Roughly speaking... EMF = electromotive force = voltage. EMF gradient is basically Volts per Meter (or unit distance).

I am sure that any charge generated by a funnel itself, would not be anywhere close to the level of energy in a CG bolt.

I am thinking more like the levels in a corona discharge -i.e. St Elmo's Fire.

But the same (extreme) EMF gradient would be present. A Funnel IS under a Thunderstorm, of course.

Approximately 1,000 – 30,000 volts per cm is required to induce St. Elmo's Fire.
I never heard of St Elmo's occurring without a thunderstorm (or high tension power source) nearby.

Jeff's calculations -- Nice Work BTW -- 7.9 kV over 2.1mm -- Definitely in the same ballpark as for corona discharge.
However, I disagree that 7.9 kV is needed for EVERY 2 DROPLETS. -- Once charge has moved from 1 drop to another, the
voltage becomes roughly the same between the next 2 droplets, etc, etc...

(All of this can become very confusing because we are talking about small "Circuits" within Very Strong Fields.)

AND we know that the EMF gradient can be easily high enough for St Elmo's (its a Thunderstorm).
So Jeff's criteria is met.

AND we know that the funnel can be a path of least resistance to the ground, making it a likely circuit path.

AND St Elmo's often becomes a ground leader for a CG strike.

-- We can make a strong case for the possibility of electrostatic discharge within a funnel cloud --

As for observations -- this is the difficult part of the argument...

I have seen upward into a few funnels, never saw any sparks. The funnels were high up and weak.

I have thought about the CONSTANT discharge and number of "bolts" observed.
I have seen Ribbon Lightning in High Winds, as probably all of you have.
The ionized air channel gets moved by the wind, and return strokes are visibly separated.

In a fast rotating wind, ribbon lightning, (or St Elmo's) might give an illusion of Many more "sparks" than
are actually prosent.

St Elmo's gives a "constant" glowing discharge.

St Elmo's is not debated, but very hard to document, not unlike Funnel Lightning.

Automatic Focus Will Not focus on fuzzy things.

Observations of St Elmo's, and of Funnel Lightning, nearly always
say that there is a loud hissing or buzzing sound.

Walls of a stronger Funnel (thereby stronger Electric Field) might block out light from inside.

BUT WHY SO MANY "OLD" observations, with so few "NEW" ones.

I Agree, RDALE !

I could go on for hours...

Thanks for reading my novel. I better quit now. So much to say, so little time...

Let's do BALL LIGHTNING next week !!.

 

[Dan Robinson]

It doesn't happen. We have literally hundreds and maybe thousands of photographic and video evidence, first-hand observations and data to completely debunk any possibility of this being real. From what I understand, the original account of the farmer looking up out of his cellar is widely believed to be an embellishment if not a total fabrication.

 

[TrumanBoyer]

It doesn't happen. We have literally hundreds and maybe thousands of photographic and video evidence, first-hand observations and data to completely debunk any possibility of this being real. From what I understand, the original account of the farmer looking up out of his cellar is widely believed to be an embellishment if not a total fabrication.

I read that the account was questionable, (and any eyewitness account should be taken with a grain of salt,)
but I never read that the story was "widely believed to be an embellishment if not a total fabrication".

All due respect here, but we do not have hundreds or thousands of photos or videos, or eyewitness accounts that show the inside of a funnel.

-T