Photo Details: Nikon D80 + Nikkor 18-135mm, ISO 100, f/8, 30s, +2.0ev
Posted on 05/28/2009 11:30:09 AM PDT by Squidpup
EIFFEL LIGHTNING BOLT: Believe it or not, bolts of lightning are shooting out of the Eiffel Tower. Photographer Hakim Atek caught it happening on May 25th:
Photo Details: Nikon D80 + Nikkor 18-135mm, ISO 100, f/8, 30s, +2.0ev
"I saw some lightning out the window of my home in Paris," says Atek. "So I set up a tripod and pointed my camera (a Nikon D80) at the Eiffel Tower. I never expected to get such an amazing picture."
But did the Tower really make its own lightning? The surprising answer is "yes."
"The upward branching in this photo shows that the Eiffel Tower actually initiated the discharge," says lightning researcher Richard Blakeslee of the NASA Marshall Space Flight Center. "In other words, instead of starting in the cloud and coming to ground, this flash started when the tower 'launched' a leader that propagated upward toward the cloud (which still served as the source of the electric field needed to get the process going). As the leader ascended, it branched out. Eventually one of the branches reached a region of sufficient charge to 'short out the cloud' and produce the return stroke pictured above."
According to Martin Uman's classic text The Lightning Discharge, upward-initiated discharges are "relatively rare," accounting for less than 1% of all lightning, "and generally occur from mountain tops and tall man-made structures." K. Berger, who studied lightning from a mountaintop location 30+ years ago, was one of the first to describe the phenomenon. Reference: Blizstrom-parameter van aufwarsblizen, Bull. Schweiz. Elektrotech., 69, 353-360, 1978.
Thank you ... great pic too. Fascinating.
LE ZOT!
That’s pretty remarkable. Thanks for the post.
I like these stories that include the camera settings. It gives me a starting point to try something similar.
The upward branching in this photo shows that the Eiffel Tower actually initiated the discharge.”
Count on the French to do things bass-ackward.
Vous êtes si drôle
The Effin’ Lighting Bolt Tower!
Keeping the Empire State Building gorilla free since 1933.
The Frenchies zotted God!
bttt
That’s what they get for letting trolls post to FR from there. Serves ‘em right.
I think the steel structure will safely transport the charges through the “skin effect”.
Nous devons capituler à Dieux de ciel!
Oui, oui, j’essaie
Very cool!
The Eiffel sparkler :-)
It is a great once in a lifetime picture.
Buddy and I had lighting strike the ground less than 10 feet from us. “Unpleasant” is an understatement. I’m fairly certain we broke most duck and cover speed records.
I remember some thirty years ago seeing similar pictures. Some crazy researchers were firing small solid fueled rockets straight up into thunderheads. The rockets were trailing a small wire (like a wire guided missile) which was attached to the launch rail. The result being an immediate return stroke to a targeted location.
Very simple and very easy but kids, DON'T try this at home. I believe they were studying high energy plasma discharges. There was no branching in their photos, the return stroke came straight as an arrow to ground, vaporizing the wire (and parts of the launch rail!) in the process.
Regards,
GtG
I’ve been outside in numerous sudden lightning storms in the desert. And when one strikes close, it is quite different than your normal thunder. Rather than a long deep boom, it is a quick sharp loud crack. One struck us so close one time that the flash burned red in my cornea and the crack was deafening. You can smell the ozone, and the air feels tingly. I have also been out at times where though there wasn’t active lightning happening, you could actually hear the earth crackling like a power line because the static charge was so ridiculously high. One time while out in a snow storm, even with everybodies hair soaking wet, nevertheless everyones hair was sticking straight out like they had their hands on a vandegraff generator. Cool stuff.
Perhaps Connor or Duncan missed a block...
Le Zot!
Nice zot picture ping
Actually, being inside the tower is probably the safest place there is during a storm. Google “Farraday cage”.
I’m a bit pop-culture-challenged. ‘Splain, please?
Sacré mérde!
Isn’t that how Benjamin Franklin met his demise?
Highlander...whenever one of the immortals is slain by another, there’s lots of lightning and broken glass...etc...
According to Martin Uman's classic text The Lightning Discharge, upward-initiated discharges are "relatively rare," accounting for less than 1% of all lightning, "and generally occur from mountain tops and tall man-made structures."ka-boom!
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NOPE!
Got it - thanks!
Le zot du frog.
Ooooooooo now that is the uber ultimate french zot shot!
Not really, he flew a kite during a thunderstorm and the wet string gave a few sparks from which he concluded that lightning is actually static electricity. He most emphatically did not pull down a lightning strike to his "Leyden Jar" (an early form of capacitor, used to store static electricity).
Under clear skies there is a voltage gradient from "ground" level of several hundred volts per meter of altitude. During a thunderstorm that gradient can rise to tens of thousands of volts per meter. The air currents inside a thunderhead create rising and falling streams of ice particles that act much like a conveyor belt moving electrons to the bottom of the cloud and leaving behind a net positive charge at the top.
Looking at the bottom of the cloud, which can be several acres in extent, the negative electrons are evenly spread across the bottom because all similarly charged particles repel each other. As the cloud moves along there is a mirror image of positively charged particles keeping pace with the cloud. This happens because the unlike charges have an attractive force.
As the cloud and it's mirror image on the ground move along they are separated by a dielectric (the air) which is a nonconductor. When the mirror charge encounters a conductor like a metal building or antenna, it flows up toward the cloud in the metal and if it's near the breakdown potential of the separating dielectric, continues upward as a weak ionized plasma. The cloud also starts a similar weak plasma column of opposite polarity downward.
If the to leaders meet the entire charge of electrons on the bottom of the cloud rushes toward the point of discharge and a current of several million amperes flows through a superheated plasma column of several meters diameter. Simultaneously on the ground the positive charged particles race toward the point of discharge and the opposing charges annihilate themselves.
The current flowing in the lightning stroke is the same as the current through the ground toward the discharge point. That current generates an enormous magnetic field which in turn induces a secondary voltage into any metal object that is not in contact with the ground. Consider it to be an air cored, single turn transformer, with several million amps flowing through the primary.
Telephone wires, electric fences, door knobs, stove pipes, &c. &c. can and do develop significant voltages. Many people who claim to have been hit by lightning have really suffered a shock from the secondary effects of a nearby strike. It is rather unlikely that a mortal could survive standing in a two meter diameter, 10,000° plasma, with a couple million amperes passing through a body comprised of mostly salt water. The most likely outcome would be a loud steam explosion and maybe twenty pounds of glowing charcoal.
Regards,
GtG
PS Franklin died on April 17, 1790, at age 84, long past his dalliance with lightning.
ping
;o)
In the series Highlander a few seasons were filmed in Paris, they filmed a fight scene on top of the tower once, looked just like that picture in fact.
Thanks - I only saw the first movie.
Thanks for the superb explanation.
One thing, though. You note, “Under clear skies there is a voltage gradient from ‘ground’ level of several hundred volts per meter of altitude.” Why? And if I’m six feet tall, or approximately two meters, why don’t I short out when I stand up?
Good question, it's true our bodies are made up of largely salt water and thus reasonably good conductors of electricity, however we are encased with a skin with much better insulating properties (in the range of millions of ohms).
If you consider a car battery for a moment, it supplies 12 volts and has an internal resistance of a few hundredths of an ohm. Ohm's law tells us that if you connect a 12 ohm resistor to the battery terminals, a current of one amp will flow. If however you connect the terminals with an errant crescent wrench, the current is limited only by the internal resistance and so perhaps a thousand amps will flow through the short circuit.
The point being that the short circuit current (which causes the damage to your body, not the voltage) is limited by the internal impedance of the power supply. When you are dealing with lead/acid batteries that is quite low so very large currents can flow. The same is true of the commercial power grid. However the voltage gradient I spoke of is actually a form of static electricity and the "source" has an impedance in the millions of ohms. The voltage can be harvested with a helium balloon and a copper wire of a couple of hundred feet, the higher you go the greater the voltage but there is almost no current available to do anything useful with it (except make some impressive sparks). To actually do something you need power which is the product of voltage multiplied by the current flowing.
Most electrical rotating machinery (generators, alternators, motors, &c.) are based on magnetic forces which are fundamentally created by current flow. It is possible to create analogs of these machines which function thru electrostatic forces (those that cause flyaway hair on dry days), those forces being created by voltage differences. I've seen electrostatic motors that spin endlessly, powered only by a wire sticking twenty feet in the air. As a novelty, they are fascinating, in practical terms they are of little use as they produce just enough power to overcome their own bearing friction.
In summary then you are protected by the resistance of human skin and the inherent internal impedance of the static power in the earths atmosphere. The game changes during a thunderstorm as a different sort of static generator comes into play (the difference between rubbing an amber rod with a piece of silk and a Van de Graaff generator) with tens of thousands of horsepower driving the process. The available voltages actually break the air molecules down to a plasma which is a very good conductor and allow huge currents to flow.
Regards,
GtG
PS You can "by-pass" you skin resistance and actually "taste" electricity by licking the terminals of a nine volt battery. Your taste buds are stimulated by the modest current flow. Do NOT try that with 120 VAC unless you are bored with life.
Oh, tasting a 9V battery is one of my old-timey ways of testing for battery life. There is no mistaking a fresh battery! ...ow!...
Thanks again for the great tutorial. One more question: where does that voltage gradient come from, and with air motions, people walking through it, and other disturbances, why doesn’t it equilibrate?
You have hit the heart of the matter with that one! I don't know and I suspect neither does anyone else. By analogy, we know the earth has a geomagnetic field. The explanations all seem to say it's because we have an iron core, although they never really say why that in and of itself would create a magnet. If you were to heat an iron sample, as the temperature rises at some point iron loses all of its magnetic properties. That happens at a dull red heat, this phenomenon is know as the Curie point. The core is molten, and well above the Curie point so how does it then generate a magnetic field?
Never the less the magnetic field exists. I'm not sure if it is actually the source of the E field but I know as fact that where there is a moving magnetic field (the spinning earth) there is an electric field as well. Electricity and magnetism are two faces of the same coin and do not exist independently. So I'll wave my hands in the air and say it's there because it is irrefutably there and was put there by whoever wrote the rules of the game.
As to why it doesn't become homogeneous, there several reasons:
It is continuously being refreshed. Another analogy here, it's rather like a lake in the mountains that has an outlet that leads to the sea. Why doesn't all the water wind up in the ocean? Because the water evaporates from the ocean and fall as rain in the mountains and keeps refilling the lake.
Also, the air is a dielectric which does not easily conduct an electric current, so the field does not immediately collapse to "ground" potential. Humidity and rain do affect the field and and cause it to weaken whereas dry air allows it to build.
It has a gradient because we measure relative to the "ground" literally. The earth itself becomes our zero reference point. The air above it contains a distributed "space charge" of free electrons (which repel each other because they are all of the same polarity) the charge is uniformly distributed and as we increase in altitude, we have more and more of the "space Charge" between us and the reference.
Anyway, that's my story and I;m sticking to it!
Regards,
GtG
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