Transcript: Chat with lightning expert Ron Holle

RSSChats & Other Live Events

Transcript: Chat with lightning expert Ron Holle

Local lightning expert Ron Holle answered questions about lightning and the monsoon.

by Kori Rumore 6/27/2012 7:19:46 PM

Submit your questions now for local lightning expert Ron Holle! He'll start answering them at noon (Tucson time).

by Kori Rumore 6/27/2012 5:48:38 PM
Ron, how far up into the atmosphere does lightning or the electrical fields that produce it extend? Into space?

by John 6/27/2012 6:55:02 PM
There is a class of rare but interesting phenomena called sprites, jets, and elves that extend from tens of miles upward into the atmosphere. Normally, a cloud-to-ground or cloud flash will stay within the cloud that in Arizona normally reaches up to around 50,000 feet in the most intense storms.

by Ron Holle 6/27/2012 6:55:29 PM
Is it true that you can be electrocuted if you are in the shower during a rain storm with lightning? Please explain. Thank you!

by Sally 6/27/2012 6:55:34 PM
When lighting strikes a house, and it happens several hundred thousand times a year in the U.S., lightning follows wiring, plumbing, and other metal structural parts of the house as it travels to the ground. Along the way, you should not be in contact with the path, such as in the bathroom or kitchen. In fact, a person was killed by lightning a few years ago in the U.S. while taking a bath,

by Ron Holle 6/27/2012 6:55:48 PM
When lightning strikes the ground, does it typically leave a burn mark or any other evidence of where it hit?

by Jay 6/27/2012 6:55:52 PM
There should be something that shows where the lighting struck, but it depends on the surface. If it’s grass or a tree, some indication can be expected. But if it’s rock, it could be difficult. The lightning channel is only about an inch across, so the exact position is not always easy to find.

by Ron Holle 6/27/2012 6:56:06 PM
Is it true that being in a car will protect you from a lightning strike?

by WillieCostley 6/27/2012 6:56:10 PM
There are no reliable safe places from lightning outdoors. Fully-enclosed metal-topped vehicles and large substantially-built structures are safe inside. Cars are safe because a direct strike to a car, which happens quite often, will have the current go around it through the metal and arc to the ground. Along the way, it may damage the tires, which leads to the mistaken myth that the tires somehow provided protection. The experience can be frightening, but it’s a safe refuge compared with the uncertain safety of being outside the car.

by Ron Holle 6/27/2012 6:56:24 PM
How much voltage and current does the average lightning strike carry?

by WillieCostley 6/27/2012 6:56:27 PM
Vaisala’s National Lightning Detection Network (NLDN) is based here in Tucson. The network detects about 25 million cloud-to-ground flashes a year in the U.S. Besides the time and location of the flash, the NLDN also measures the signal strength in kiloAmps. The typical strength of a cloud-to-ground flash is around 20,000 Amps; some are weaker and some are much stronger. Needless to say, there are no weak lighting flashes, and every one is capable of causing damage or injury.

by Ron Holle 6/27/2012 6:56:39 PM
I want to welcome Ron Holle to today's monsoon chat. Ron, thanks for your time! Tell us a little bit about your background. When did you decide to study lightning?

by Kori Rumore 6/27/2012 6:57:58 PM
I studied thunderstorms as a meteorologist with NOAA (National Oceanic and Atmospheric Administration) for many years in Florida, Colorado, Oklahoma, the Caribbean, and west Africa. During the late 1970s, this new instrument came along called a lightning detection network that was developed at the University of Arizona. I started looking at the data as the networks spread and matured, and found it to be a logical and interesting extension of my meteorological studies.

by Ron Holle 6/27/2012 7:02:42 PM
So, how much lightning do we usually get around Tucson, say, during the monsoon, Ron?

by Kori Rumore 6/27/2012 7:04:50 PM
Almost all of the lightning in Arizona is between late June and the middle of September during the monsoon season. Arizona averages about two-thirds of a million cloud-to-ground flashes a year. Pima County has between 40,000 and 80,000 cloud-to-ground flashes a year. Yesterday, we had a good storm in terms of lightning, when there were 3902 cloud-to-ground strokes in southern Arizona between noon and midnight (I think yesterday’s map will be posted with this comment). Remember that a cloud-to-ground flash has one or more return strokes, so these 3902 strokes were probably contained in about 1000 flashes.

by Ron Holle 6/27/2012 7:11:03 PM
by Kori Rumore 6/27/2012 7:13:43 PM
That has been considered a number of times. There are three problems to overcome. First, lightning usually does not strike a single location very often. A really tall tower or building only has a few dozen direct strikes a year. Second, the strokes within a flash only last a portion of a tenth of second. Third, it would be necessary to store the energy so the surge from the short but intense lightning strike doesn’t enter the power grid. Such a battery or storage device would probably be very expensive and not cost effective. So, such infrequent and short but intense events are hard to make into a practical solution.

by Ron Holle 6/27/2012 7:17:21 PM
Could it ever be feasible (perhaps in the far future) to harness the energy of lightning for electrical power?

by WillieCostley 6/27/2012 7:19:15 PM
Hi, I recently switched to satelite TV and I wanted to know if lightning could strike a satelite dish, (does it act like a lightning rod? Could it damage it?)

by Jorge edited by Ron Holle 6/27/2012 7:25:18 PM
The most likely problem is that lightning will strike a power pole or some part of the electrical grid near your home, and enter your house. When it does, anything can be damaged by the power surge. It might be good to have a surge suppressor placed between your house’s incoming power to the satellite dish system and the dish. The same can be said about any other electronics in your house, such as sound systems, TVs, and computers. I have been told that a surge suppressor needs to cost around $75 to provide much protection from a close strike. As far as being a lightning rod, lightning tends (not always) to strike things that are tall, isolated, and/or pointed, so it doesn’t go out of its way to find a dish mounted on the side of a house. The most likely issue is that a power surge from a strike to the house or something nearby would end up damaging the equipment.

by Ron Holle 6/27/2012 7:25:21 PM
Can lightning strike you if you can't hear thunder?

by Noah edited by Ron Holle 6/27/2012 7:25:31 PM
Thunder can be heard up to 10 or 12 miles away in quiet conditions, and possibly up to 15 miles in extreme calm situations. In the city with cars, wind in the tress, and so on, it’s more like 5 to 7 miles, and sometimes less. Heat lightning is normal lightning that is too far away for its thunder to be heard.

by Ron Holle 6/27/2012 7:28:49 PM
How many people are killed by lightning in the U.S. and elsewhere?

by Kori edited by Ron Holle 6/27/2012 7:32:48 PM
In the U.S. in the last 10 years, 37 people a year have been killed by lightning. The number has been decreasing steadily for a number of reasons that are not well understood. Around the world, the estimate ranges from 8,000 to 24,000 deaths a year, mostly in less developed countries where people work in outdoor labor-intensive agriculture and do not have safe buildings or vehicles to reach when a thunderstorm arrives.

by Ron Holle 6/27/2012 7:32:52 PM
Someone once told me her uncle was struck by lightning as a boy when he was running outside during a storm, but that he was wearing rubber-soled shoes--so he just momentarily froze and then kept on running. She claimed he didn't even realize it had happened. Is that possible or had she been told a tall tale?

by WillieCostley edited by Ron Holle 6/27/2012 7:40:59 PM
There are several parts to this story. First, the rubber soles had nothing to do with being safe. Lighting originates thousands of feet above the ground, tears apart the air in between, and comes to ground, so a quarter inch of rubber is not providing safety. Instead, this is likely a situation where lightning hit nearby, and ground current reached the runner. The effect of a lightning ground strike decreases with distance across the ground. The distance from a strike to ground that does not cause injury is not known, but it’s probably on the order of tens or hundreds of yards. If it struck at 10 or 100 yards away, for example, then a slight jolt could be felt but it was not strong enough to be damaging. The person should feel extremely fortunate that the flash did not randomly strike much closer, when the outcome could have been much worse. This same idea of the decreasing danger with distance is part of the reason why about 90% of people who are affected by lightning are not killed - they are too far away form the actual location of the strike.

by Ron Holle 6/27/2012 7:41:02 PM
Which part of the world would I have to travel to to find the place with the most lightning on Earth?

by Kori 6/27/2012 7:41:06 PM
The highest lightning frequency appears to be in central Africa, northern Venezuela, and/or some large islands in Southest Asia. Those areas have several times as much lightning as Florida, and many more times as much as in Arizona. Vaisala here in Tucson now has a global lighting network, and we hope to have better ideas about this pattern in the future.

by Ron Holle 6/27/2012 7:44:20 PM
There are tall construction cranes near the UA.. How do they manage lightening strikes?

by Patty pearson edited by Ron Holle 6/27/2012 7:47:05 PM
Cranes are tall, isolated and/or pointed, so they are potentially preferred targets for lightning. There have been quite a few incidents of deaths and injuries from lightning striking cranes around the U.S. An operator needs to be off the crane when lightning is in the vicinity, unless it has been specifically cleared by a lightning protection specialist.

by Ron Holle 6/27/2012 7:47:09 PM
We have time for just a few more questions. Get yours into Ron now!

by Kori Rumore 6/27/2012 7:50:40 PM
I had a swim meet that was scheduled for 5:00p.m. yesterday during the storm, it was cancelled because there was lightning 7 miles northwest, would swimming have been dangerous with lightning that far away?

by Noah Tek edited by Ron Holle 6/27/2012 7:57:01 PM
A swimming pool, outside or inside, is vulnerable. It’s not the area of the pool itself, but the large connected area of plumbing, wiring, and metal structures. The most likely situation is that lightning will hit a power pole near the pool, or some other part of the electric power system, and enter the pool complex. There are plenty of paths to follow, and people are often in contact with plumbing, wiring, or metal structural parts of the complex.

The distance of 7 miles is reasonable, based on a large amount of studies that have been made. For example, the next flash in a thunderstorm is more than 6 miles away 20% of the time, which is frequent enough to take action. In this case, going to the car and waiting until the storm finishes is a simple and effective solution, then the pool can open again when the lightning threat is gone.

by Ron Holle 6/27/2012 7:57:05 PM
Are we safe from lightning in a rubber tired vehicle

by bob 6/27/2012 7:57:44 PM
There are no reliable safe places from lightning outdoors. Fully-enclosed metal-topped vehicles and large substantially-built structures are safe inside. Cars are safe because a direct strike to a car, which happens quite often, will have the current go around it through the metal and arc to the ground. Along the way, it may damage the tires, which leads to the mistaken myth that the tires somehow provided protection. The experience can be frightening, but it’s a safe refuge compared with the uncertain safety of being outside the car.

by Ron Holle 6/27/2012 7:57:59 PM
Is it true that the electrons from the ground shoot up towards a lightning bolt and meets it in the air before it connects with the ground? (this would make it seem like electricity is shooting out of what ever the lightning is about to strike)

by Noah Tek edited by Ron Holle 6/27/2012 8:02:26 PM
A short answer is that electrification begins in the cloud at 15,000 to 25,000 feet above the ground here in Arizona. There needs to be a mixture of small hail, supercooled water droplets, and an updraft. This mixture initiates the flash, which comes toward ground. Under this electrified cloud, tall and pointed objects on the ground send up leaders to reach toward the channel coming to ground. When the connection is made, charge is lowered to ground, then the current goes back up the channel and that’s what we actually see.

by Ron Holle 6/27/2012 8:02:29 PM
I just assumed that a crane operator could be safe from lightning inside the metal control cab. Is there too much exposure then?

by Patty pearson 6/27/2012 8:02:35 PM
It depends. Recall that the phrase for a safe vehicle is being fully-enclosed and metal-topped. There needs to be a full Faraday-cage like effect with a full metal sheath around the person. Unsafe vehicles are open sided and made of fiberglass, so the crane is not clearly a safe solution

by Ron Holle 6/27/2012 8:05:19 PM
I want to thank Ron Holle for taking time to answer so many questions about lightning — during Lightning Safety Awareness Week. And, thanks to all of you for participating in today's chat!

by Kori Rumore 6/27/2012 8:06:33 PM