Talk:Lightning

The lightning page explains producing/separating electric charge by triboelectricity process among ice particles (or dust). But the triboelectricity page (and the Van de Graaff page), says that the rubbing particles must be of different material to produce/separate electrical charge. If so, the ice particles (or dust) being of the same material could not produce static electricity. These pages seem to contradict one another. Any comment? RS

First, nobody understands how regions of charge in thunderstorms are produced. It's still an open question in physics. There are several theories, but each of them has problems, chief of which is that freezing water SEEMS to play a critical role, yet some rare clouds develop charge at far above 0C degrees. Any popular book that states how lightning really works is wrong. Instead try Dr. Martin Uman's book "Lightning." That said... the most accepted current theory involves charge separation between water and ice, with half-frozen raindrops called "graupel" spalling off ice shards. If I understand correctly, the tiny ice shards end up charged, with the raindrop developing equal and opposite charge, then the large raindrops outrun the tiny ice shards, causing huge positive and negative regions to appear within the storm. --Wjbeaty 18:45, Mar 2, 2005 (UTC)

The article states that the charge separation occurs partly due to polarization - this is obviously wrong. Polarization would cause negative charge to move towards the positively charged upper atmosphere and positive charge towards earth - but the opposite is true. 193.171.121.30 17:05, 10 Mar 2005 (UTC)

Some say that lightning can pass through glass windows. Othes are sceptical. JRG

Apologies for accidental deletion of this page. I have no idea how it happened, I can assure you it was not intentional. Sorry again. --/Mat 19:24, 4 Apr 2004 (UTC)

Odd - someone else managed to change this page to a null entry (like I apparently did) - anyone know if this is a user-error, browser error, page-error or wiki error? --/Mat 15:34, 9 Apr 2004 (UTC)

Contents

1 Ozone 2 Lightning rods 3 Positive lightning 4 image/streamer 5 Confusing language in "History of lightning research"

Ozone

The ozone page says that lightning produces ozone. Has this ever been measured? JWSchmidt 05:20, 12 Apr 2004 (UTC)

"Researcher Renyi Zhang of Texas A&M University helped lead a study on the impact of lightning, and the results are surprising: Lightning can ... increase ozone levels as much as 30 percent in the free troposphere, the area that extends 3-8 miles above the Earth's surface. " - from EurekAlert (http://www.eurekalert.org/pub_releases/2003-03/tau-ssl031903.php).

People have known that lightning produces ozone since the days of Benjamin Franklin, if not earlier. It was the fact that man-made electric discharges caused the same ozone smell as lightning that led Franklin to investigate the electrical causes of lightning. (Source: Ask A Scientist (http://www.newton.dep.anl.gov/askasci/gen99/gen99672.htm).)

-- Heron 15:11, 27 May 2004 (UTC)

Lightning rods

I was under the impression that a lightning rod actually prevented lightning from striking, rather than providing a lower resistance conduction path. The idea is that the lightning rod allows charge to dissipate from the structure it is attached to, thus reducing the potential difference between the cloud and structure, reducing the chance of lightning striking that location... That said, I've also seen videos of lightning striking the tops of skyscrapers, so I'm not entirely confident this is their *only* purpose...

There seem to be conflicting opinions about this. Benjamin Franklin believed that "the electrical fire would, I think, be drawn out of a cloud silently, before it could come near enough to strike". He proved that some charge was extracted "silently" from thunderclouds by a lightning rod, but this is not the same as preventing a lightning strike. HowStuffWorks (http://science.howstuffworks.com/lightning9.htm) says that "Regardless of whether or not a lightning-rod system is present, the strike will still occur. ".

Franklin's theory suggested that pointed rods were better because they caused a silent discharge and prevented lightning strikes, while British scientists believed that blunt rods were better because they induced strikes to occur where they could be safely conducted to ground. The debate became polarised for political reasons, with Americans supporting Franklin's view and the British clinging to the opposite view. I suspect that this rivalry continues today. I don't want to take sides here, but I note an article in USA Today (http://www.usatoday.com/weather/resources/basics/2000-05-15-lightn-rod-tests.htm) entitled "Researchers find that blunt lightning rods work best". I wouldn't be surprised to find other articles supporting the opposite point of view. -- Heron 12:31, 24 Jun 2004 (UTC)

I guess it would depend on the surroundings, a pointed rod should be better for sending out streamers (and by that "attracting" the lightning) because of the "concentrated" electric field at the point, but I'm not familiar enough with the electrical properties of air in very strong electrical fields to make a qualified remark really.--Deelkar 14:57, 9 Sep 2004 (UTC)

however, a lightning rod (either pointed or blunt) increases the probability of a somewhat controlled lightning strike, i.e. the lightning not hitting anything inflammable. However, if the lightning strikes near to a house, regardless of striking the rod or a tree or the Ground directly, there is a certain amount of EMP that can damage electronic equipment, even if it is protected or even disconnected. --Deelkar 15:04, 9 Sep 2004 (UTC)

Some facts never stated in the lightning rod controversy... a cloud-ground lightning streamer is triggered SEVERAL MILES UP, and the electric current sent out by a lightning rod is made of charged air and is subject to wind speed. How can a relatively small lightning rod have any effect on a gigantic stormcloud miles away? And since there is no hurricane-force wind coming out of the tips of lightning rods, how can the slow-moving charge sent out the rod ever reach the stormcloud at all? The obvious answer is that it can't. (Imagine that the tip of a lightning rod was emitting colored smoke which is attracted upwards. This "smoke" moves slowly, and if the wind is blowing, then it's wafted downstream faster than it can rise.) Early physicists were reasoning from analogy, where a sharp needle could easily discharge a charged metal ball from many inches away. But since the "electric wind" which discharges the metal ball only moves at inches per second, the analogy doesn't work for the immense distances involved in trying to discharge a storm cloud. Perhaps the charged air sent upwards by a lightning rod could deflect an incoming streamer. Or perhaps the mass of charged air could electrically shield the rod, so that the incoming streamer would trigger an answering streamer from some other building, thus "deflecting" the strike.

The accumulation of charge in the cloud produces a field around it that orients nearby molecules to have their ends pointing in the opposite direction of the potential field. For example, if a cloud has a large negative charge and the ground is neutral, then air molecules will point their positive ends towards the clouds and negative ends towards the ground. This process is nearly instantaneous. As more charge is built up in the cloud, more molecules will align themselves. There will be many possible paths from the cloud to the ground where all the molecules are aligned. Eventually one of these paths will have enough potential energy across it to tear the electrons from the molecules, forming a temporary plasma conductor in the air. This is when lightning actually strikes. It is more like a rubber band that has been stretched too far than a baseball that is hurled at the ground. The reason that a lightning rod works is that it provides a generally shorter distance to ground for the lightning, and greatly reduces the amount of resistance between the cloud and conducting ground (normally the lightning would have to go through rock, glass, trees, soccer players, whatever. A lightning rod is metal and has less resistance than these other substances). Since it is an electrically shorter distance, it will tend to be easier to break down the air between the lightning rod and the cloud instead of just the regular ground. Think of it as the difference between stretching a tiny rubber band to the breaking point and stretching a big rubber band to the breaking point. And of course, once the air breaks down, the charges in the ground and cloud are equal, so there is no longer a potential across the air, so there can be no more lightning until it builds up again. Edit - reading more of the argument: the reason that a lightning rod could reduce the chance of a lightning strike is that some work is done by the potential to align the molecules, and then a lot more work is done to "stretch" them apart. If you do enough work this way it should reduce the potential. --Ignignot 20:15, Mar 2, 2005 (UTC)

speaking of franklin, according to the article on franklin the famous kite experiment may or may not have ever actually been performed, and was only mulled over as far as we know. either that article or this one is in error.

Positive lightning

The article comments on positive lightning: It occurs when the stepped leader forms at the positively charged cloud tops, with the consequence that a positively charged streamer issues from the ground. Shouldn't that read ... with the consequence that a negatively charged streamer issues from the negatively charged ground away from the cloud??? --Martin Rehker 13:00, 6 Aug 2004 (UTC)

image/streamer

since streamers sometimes (?) are visible, could it be that the faint light to the right was a streamer that did not connect to the cloud ligntning or the cloud-ground lightning to the right? --Deelkar 14:44, 9 Sep 2004 (UTC)

Confusing language in "History of lightning research"

I added the "confusing" boilerplate in response to the immensely confusing language used in the "History of lightning research" section. I had to read this section several times to understand it. It looks like the author was sitting in front of a thesaurus picking pretty words. I'm not an expert on Benjamin Franklin, but hopefully there's someone out there who can write about him while maintaining Wikipedia's standards of readability. --Aeki 01:12, 7 Apr 2005 (UTC)

It's just old writing; by someone who never played with Nintendo or Sega games, who never used a computer to edit his writing, never saw a spell-checker or online thesaurus.

But much more than that, even—someone who never even watched a television program in his whole life, likely. Never listened to the radio either. Never had electric lights in his house, never saw an electric outlet. This might be from the 1911 Encyclopædia Britannica, or something even older (and if from the Britannica, probably a holdover article from an earlier edition). Someone who didn't have the words in his vocabulary to deal well with the phenomenon of electricity. Sparks he'd seen, from fire and flint on steel more than from electricity; and he'd seen a Leyden jar. Gene Nygaard 02:23, 7 Apr 2005 (UTC)

Thanks for the humorous response, Gene. I was personally reminded of the English used in Mark Twain's The Prince and the Pauper. At any rate, the dialect used appears to be only in that section, so it'd be nice if someone born after the War of 1812 with knowledge of Franklin's experiment could bring it up-to-date. --Aeki 05:59, 7 Apr 2005 (UTC)

Hey, give the author a break, Leyden jars were probably a lot more common in 1828. (looks like the section was lifted from about half way down this page (http://www.ibiblio.org/pub/docs/books/gutenberg/1/2/8/7/12873/12873-h/12873-h.htm)) -- Solipsist 07:20, 7 Apr 2005 (UTC)

Is it appropriate for us to be copy/pasting 177-year old texts from Project Gutenberg and saying "Poof! I have me a Wikipedia article!" like this? Nevermind that there's no citation of sources. I know it's public domain. Still, if we are basing our science articles in 2005 on texts that have become public domain because of their age, isn't that...misguided? I maintain that a current article on a scientific subject should at least be written in current language. --Aeki 07:35, 12 Apr 2005 (UTC)

No you're right, its one of the oldest examples I've seen. Quite a few articles are based on the 1911 Britannica, which is often seen as too old fashioned and out of date. We have templates to encourage updating that text. However, here the best course of action is probably to remove the section entirely and replace it with a stub. This text is most likely hampering people from writing a good history. -- Solipsist 08:37, 12 Apr 2005 (UTC)

OK, I rewrote the Section in conſern in a more legible manner, using the previous Source, in the modern Language. 68.39.174.39 05:58, 16 Apr 2005 (UTC)