Lightning and Caves

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Lightning and Caves

Postby George Phillips » Jan 24, 2007 3:26 pm

I'm looking for information on lightning and caves - specifically regarding ionized air in caves, how the ionized air is formed, how it attracts lightning strikes to cave entrances and how or if the electrical pulse from a lightning strike at or near a cave entrance can be transmitted through the ionized/humid cave air to points deeper in the cave.

Specifically interested in scientific articles on this subject (Journal of Cave and Karst Studies, other journals).
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Postby Caverdale » Jan 24, 2007 10:37 pm

The only article that comes to mind was published about 5 years ago in GEO2, the publication of the Geology and Geography Section, and authored by John Gookin, of NOLS in Wyoming. Much of the article was taken from a foreign publication. My library is still unorganized from a house remodeling last year so I'm unable to look it up.

I am also interested in the subject. For the past decade or so I have been conducting magnetometer surveys over known and unknown lava tubes. Interestingly, at the entrance of breathing lava tubes the magnetometer anomalies indicated many, many lightning strikes, enough so as to totally obliterate the expected anomalies. Away from the entrance lightning strikes are relatively few and randomly distributed. I have presented this result at two papers on magnetic geophysical prospecting for lava tubes at NSS Conventions. Just as you presume, I have mentioned that the lightning strikes are due to ionized air exiting the entrances. Not so, say experts in the audience. More than likely, the lightning channel is created by moisture in the cave air. I had thought that perhaps some radioactivity, such as radon, might create ions, but this was discounted by some people much smarter than I. Since than I have tried find references about ionization of cave air but without any luck.

I have never read about lightning entering and following a cave passage, except in cases where it followed wet ropes or metal cable ladders. However, there have been several mentions in the NSS News and Grotto publications reproduced in the Speleo Digest of cavers being struck by lightning in while inside caves. All of this is due to lightning traveling through the ground, not down the passage. There might even be a case of cavers observing a real lightning discharge inside the cave. This is a vague memory. Hearing thunder booms from lightning while far underground is not uncommon, either.

When measuring magnetic anomalies inside lava tubes, some of them are so intense that they could only be caused by the direct passage of current from lightning strikes on the surface directly to the walls of the tube and there is no evidence that the current came down the passage from the entrance. Unfortunately, I have been unable to find magnetic evidence of lightning strikes around breathing limestone caves because of the lack of magnetic material.
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Lightning and Caves

Postby George Phillips » Jan 25, 2007 9:31 am

Dale:

Thank you for the reply. I have seen the GEO2 article - it is the only article I could find doing a search on "lightning" and "caves".

I recall reading - not sure where - perhaps NSS Incidents / Accidents bulletin - about cavers who were surveying and felt an electrical shock while holding a metal tape deep inside the cave. They later found out that there had been a thunderstorm/lightning outside when the event happened.

I'm wondering if ionized or humid cave air can tranmit electric current underground if a lightning strike occurred near an entrance?

There has been much interest in WV regarding the lightning strike as the possible ignition source for the Sago Mine explosion last year. Investigators believe a lightning strike in the area at the time of the explosion ignited a flammable mixture in an inactive part of the mine. They have not been able to determine the path the lightning took to get into the mine.

I recalled the connection between caves and lightning and would think the same would be true for mines - ionized, humid air in the mines could transit an electrical pulse through the air where any metallic object - deep inside the mine or cave - could act as a "collector" or "antenna" (similar to the surveying tape) and could pick enough charge to produce a mild electrical discharge which might be the ignition source. The investigators estimate the energy of the ignition source to be very weak - on the magnitude of an energy in a sneeze.

Just wondering if there is an analogy between cave and mine environments.

If you do a search on coal mines, explosions and lightning you will find there is a surprisingly (to me) high frequency of lightning associated ignitions of explosive gas mixtures in mines.

Regards,
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Postby Caverdale » Jan 25, 2007 11:26 am

Electrical current must always take the path of least resistance. This is a fundamental law. Outside a cave or mine entrance a plume of humid or ionized air would present a lower resistance path for lightning than the surrounding drier air and would therefore strike near or in the entrance. Inside a cave I doubt that humid air would present a lower path of resistance than a wet floor or walls so lightning would probably flow along a surface, if it flowed at all. In the case of lava tubes I have not found evidence that lightning flowed along a passage surface. If lightning entered a passage, it came through the bedrock from a strike on the surface.

In a mine the situation is totally different. Every mine passage starting from the entrance has a wide variety of pipes, electrical wires, railroad tracks, etc., that would present a much less resistance to electrical current flow from lightning than the moist or ionized air. Even with these excellent conductors present, lightning could still travel from surface to a mine passage through the earth and not go down a passage.

The topic needs some research.
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Postby Komebeaux » Jan 25, 2007 10:16 pm

A good friend of mine was struck by lightning in the entrance of a cave once. People on the outside at the time said the lightning made a bee line down to the cave entrance. He was extending his hand up to reach for something and it hit the palm of his hand. Fortunately he survived with only a scar and a great story!
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Lightning Bolt Passage

Postby wvdirtboy » Apr 12, 2007 9:44 am

A group of cavers from the WV Assoc. for Cave Studies (http://WVACS.org) reported being struck while holding a metal tape in Luddington's Cave, WV. A thunderstorm had rolled through while they were in the cave and I think the above story about a similar incident is actually this one.

The (large) passage being surveyed was given the name Lightning Bolt as a result of the incident.

Also, WVACS has a table covered with logos of the largest caves in the area and the logo for Luddington is a lightning bolt in a cave passage.
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Postby George Dasher » Apr 12, 2007 10:16 am

I think they named it the Thunderbolt Passage (or Room). They were using a metal tape, and it was Bud Rutherford who was shocked. I couldn't find the reference in my five-minute search of ACAs, but the incident may predate the publication of ACA.

By the way, it it Ludington Cave. Bob Handley went on a campaign a few years back to get people to start using the correct name. Or maybe he was just campaigning for me to use the correct name.
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Thunderbolt

Postby wvdirtboy » Apr 12, 2007 12:52 pm

You are right George! And as I recall it happened in the '60s or early '70s.
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Lightning and Caves

Postby Larry E. Matthews » Apr 13, 2007 10:38 am

Does anybody have an Index for the NSS News handy?

I am fairly confident that Bill Halliday wrote an article on this very subject, but perhaps 20-30 years ago.

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P.S. Anybody remember the NSS Convention where lightning struck in the campground and one unfortunate lady was wearing nylon panties?

They melted !!!! They had to scrape them off of her in the Emergency Room. True story !!!
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Postby Phil Winkler » Apr 13, 2007 12:14 pm

So, they melted because she had hot pants or what? :D
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Lighting Strike In Campground

Postby Larry E. Matthews » Apr 13, 2007 1:17 pm

Fortunately, the lightning did not strike close enough to harm anyone seriously, but the heat from the strike melted the nylon underware.

Does anybody remember which NSS Convention this was?

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Postby Squirrel Girl » Apr 13, 2007 7:53 pm

Lightening struck the campsite I was camped at at the '88 Hot Springs convention. Only because I wasn't in camp at the time, did I not get hit. I only knew some of the people I was camped with that time. I think a cooler and a lantern melted? I can't remember. '88 was a long time ago. Don't remember hearing about any panties. Sounds like an urban legend to me.
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Postby Teresa » Apr 14, 2007 9:10 am

My husband was at that convention. If you do a net search on NSS convention/lightning you get a hit on Sligo Grotto, noting that a lady named Lynn Ott was nearly fried by lightning there.

We also know that Jane Fisher, of Meramec Valley Grotto, was extremely near the strike, which hit a rain canopy and fused the aluminum poles. She was taken to the hospital--my husband was heading back and saw the ambulance leave the campground, and was so informed at the time by other MVG cavers. Apparently there was an aluminum lawn chair in proximity which took part of the jolt, too.

No definitive report on the condition of her underwear was given at the time. Jane is 93 now, and though in frail health, still a member of the grotto. I recall Jane talking about how her usually neatly coifed hair stood on end.

Being struck by lightning (while not fun) is not necessarily fatal. When in high school, one of my classmates father's was struck while putting up a tent (again, aluminum poles) and felt the lighting go through him, but somehow, it discharged harmlessly elsewhere.

The moral seems to be-- avoid aluminum during a lightning storm. No beer!
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Fried Underware

Postby Larry E. Matthews » Apr 15, 2007 3:29 pm

Not only did her underware really melt, she was even called up on the stage during the Awards Ceremony at the Friday Night Banquet and given an Extra-Extra-Extra Large size pair of white panities with: "I Got My Ass Fried At the 19?? NSS Convention" written on them.

Needless to say, she got a standing ovation.

It was a close call, and fortunately no one was seriously hurt or killed.

We were told that the doctor in the Emergency Room had to carefully scrape off the melted nylong with a scalpel.

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Postby shottheradio » Jun 25, 2007 10:19 pm

Our cave has been hit twice in the past year. I'm thinking it could be a potential hot spot?
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