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Lightning (Guest Article)
And I must state that I am not an expert in the phenomena of lightning nor do I have any specific knowledge, or experience, which allows me to draw certain conclusions you’ll read later in this report. I have spent a considerable amount of research time at work studying the formation and structure of lightning. During that research, I consulted with Dr. Martin Uman, Department Head - Electrical Engineering, University of Florida. Dr. Uman is a world renowned expert in the field of lightning and has published dozens of articles and books on lightning. This report in no way directly represents Dr. Uman’s views. It is simply a recount of what I think I heard during my meetings with him, and what I have learned through my research study..
I have simplified some of the explanations you’ll read. In so doing, actual sequences of events or definitions may have been somewhat clouded, or omitted altogether. However, the basic facts remain valid as best as I can recall them. Also, there is still a great deal of mystery around the formation, function, and discharge of lightning, it is not 100% predictable. And one last opening comment. Any recommendations you read are nothing more than what I would do if caught in a storm. I make no claim as to effectiveness, nor do I mean to imply that following these recommendations puts you out of harms way. How’s all that for a disclaimer. On to the report....
If you hear the thunder, the lightning did not strike you. If you saw the lightning, it missed you; and if it did strike you, you would not have known it. That consoling observation was made by the late Karl McEachron, and seemed to set the appropriate tone for this report.. I would feel remiss if I didn’t mention right up front that ocean going vessels as well as some offshore boats have lightning arresting systems, much like the lightning rods and grounding system you may have on your home. Although in my opinion these systems offer very little protection to us in our bass boats, you may read more on the subject in Peter E. Viemeister publication The Lightning Book published by the MIT Press in April 1972. And before moving on to the subject at hand, that same author stated, "The odds are remote: Don’t worry yourself too much about being killed by lightning: the odds are about a million to one per year …”. In North America alone, that’s roughly equivalent to 200 ~ 300 deaths per year! And the vast majority of those 300,000,000 people in N.A. are NOT in the middle of a lake perched on the highest, ungrounded point in the vicinity! Think about it, are people in buildings or at home during an electrical storm likely to be struck? I don't think so. And how many of the 300 million people are outside during a storm? Let's just pick a number - say 50 million? That increases the chance of death due to lightning stroke of folks most likely to be struck, on the order of six fold. When you’re on the water – don’t worry, just be prepared!
There are many types of lightning but the most common which carries potential for damage or injury to property or living things on or near the ground is called a “Cloud To Ground, Negatively Charged, Downward Traveling Stepped Leader”. You know the ones… a bright, typically jagged flash of light from a cloud to the ground (or ground to cloud if have super human sight), often containing many less bright flashes which emanate from the main flash, similar to the roots of a plant. A vast majority of all lightning strokes in North America are of this type. The primary exceptions are on shore or off shore near the East coast. East coastal stokes are slightly different but are just as, if not more, devastating. All of these strokes transfer enough charge to POTENTIALLY kill, cause permanent disabilities, or destroy property. And of that 50%, one half DEFINATELY have enough charge to kill or destroy. The distinction between “potentially” and “definately” cannot be identified until after the fact, and the word POTENTIALLY is a relative expression as you’ll read. Here’s how it all works.
When a cumulonimbus cloud (thunderhead) builds in size and density, the electrical charges within, both positive and negative also build. It is the physical nature of these charges to attract one another but pressure differentials, temperature differences and wind currents within the cloud prevent it. In most cases, the positive charges collect and build in the upper layers of the cloud while the negative charges build in the lower. There are debates in the scientific community as to why this occurs - fact is they do. Meanwhile, back on the ground, the surface of the earth is covered with positively charged particles - this is also a fact of physical nature. As the negative charge in the cloud builds, those positively charged particles on the surface begin to collect into “strings” and migrate upwards toward the negative charges in the cloud. By physical law, the opposite charges are being drawn together. The result of this attraction generates an electrical field between the cloud and the ground. These strings of positive charges are called “streamers”. They collect and migrate upwards from everything on the surface. Flat or rounded objects tend to spread streamers out over a broader area, more horizontally oriented than vertically. Pointed objects, like trees and fishing rods tend to distribute streamers upwards, in the vertical plane.
Electrical Fields are defined in terms of “Volts Per Unit Length”. Typically, when the E field grows to a level of ~450,000 Volts / Meter, the air between the negative and positive charges ionizes (becomes conductive), the negative charges explode out of the cloud through the ionized path at a rate on the order of 1x10(5) Meters / Second. That’s roughly 110,000 Miles / Hour. When the electrical path has been completed (as above), electrical current is generated. Many variables dictate how much current. The magnitude of the negative charge in the cloud, the distance between the cloud and the earth, the saturation level of the atmosphere and the electrical resistance in the ionized path (including the fisherman) to name a few. Lightning does not transfer volts, or watts (power), or current. It transfers electrical charge, (Q). Charge transfer is expressed in terms of Coulombs, and 1 Coulomb equals 1Amp applied for 1 Second, or a Coulomb is an Amp.Second. The math becomes somewhat involved. To state it simply, to determine the charge transfer of a lightning stoke, the area under the stroke’s waveform must be calculated. And this is done by instrumentation which captures the electrical “signature” of the stroke.
The type, and severity of the stroke, can be calculated from the waveform through intergration (determining the area under the curve). If you remember the phrase from the first paragraph; all of these strokes transfer enough charge to POTENTIALLY kill or destroy. And of that 50%, one half DEFINATELY have enough charge to kill or destroy.
The waveform of those strokes that transfer enough charge to POTENTIALLY do damage or cause injury or death contain a simple peak of current with a rise and fall time of approximately 5 micro seconds each. A very small stroke of this nature may rise to a peak current of (on the order of) 35,000 Amps. Doing the math, that would represent much less than a Coulomb (an Amp.Second) of charge transferred. Would that knock you on your buttinsky? You bet! Do permanent damage – probably - cause death? I don’t have a clue! I am sure however, that these are the strokes that you hear of occasionally, where the person hit “walks away”. But this is at the very low end of the potentially damaging strokes. The negative charge in the cloud isn’t always discharged during the first stroke. This results in a second, third, fourth etc. “return stroke” within ~50 milliseconds of one another. You seen lightning that seems to be “pulsing”? That’s what’s happening. And the charge is additive from each spike! Dozens of return strokes have been measured during a single lightning event. At the upper end of severe lightning, with peak currents on the order of 300,000 amps with rise/fall times up around 50 micro seconds or so, the charge transfer is on the order of 15 Coulombs through the “first” return stoke. This is only my guess, I am not an expert nor do I pretend to be…but at 15 Coulombs you’re probably toast! To continue “guessing”, I suspect that more than 80 ~ 90% of these POTENTIALLY damaging or life threatening strokes will kill or permanently maim. And don’t forget that this type of stroke is only 50% of the total number of stokes that hits ground.
The next type of stoke to be discussed falls in the category that it will DEFINATELY kill or destroy. To refresh your memory, this type of stroke occurs (as stated above) in of 50% of all stokes. In other words, one out of every four stokes that hits the ground or water in North America, statistically is of this type. The front end of the waveform is similar to the “potentially” damaging stoke discussed above. But, among other components, the waveform contains a component called “continuous current”(CC).
After the initial spike in the waveform, the current does not return to zero. Instead it transitions through another component of the waveform into the CC component. CC is a steady state of current ranging from milliamperes to as much as 100 Amps lasting up to, or even more than a full second of time. Remembering that charge is defined as the area under the curve, the CC “curve”, which is just one of four components of this type of waveform, is essentially a rectangle, 50 Amps tall by 1 Second wide. The area is then 50 x 1 = 50 Coulombs. FIFTY! If less than a single Colomb will knock you onto your keister, and 15 Coulombs would probably put you in the hospital or perhaps the morgue, FIFTY will certainly turn your lights off.
OK, sum it up. When you add the probabilities from both the potentially life threatening and the definitely life threatening strokes, you arrive at 95%. To be clear, statistically, 95 out of 100 “Cloud To Ground, Negatively Charged, Downward Traveling Stepped Leader” lightning stokes have the energy to kill. As if that isn’t bad enough, you don’t have to be struck directly. Lightning tends to move at will, bouncing, ricocheting, hopping from place to place. Hopefully you’re not in the path or touching that which it bounces to. There are even recorded events where people in a boat drowned after their boat was struck by lightning burning a hole clean through the hull, causing the boat to sink! No life vests on – that’s another story!
So… What do I do when caught by a storm while on the lake. Here’s a typical sequence. When I first notice that a potentially lethal storm is approaching (no lightning noted yet), I tend to explore my options and move to a fishing hole that offers quick access to a place to beach, or dock the boat, and continue to fish from that spot. . Do I need to mention that I don’t run TOWARDS the storm? Bear in mind that lighting has been documented to have struck as far as 10 miles away from the thunderhead! I would prefer to be where the truck is parked so I could jump into the vehicle – that’s a relatively safe place to be during a lightning storm. Naturally if you live on the lake, have friends that live on the lake, or have a building such as a hotel, restaurant or tackle shop near by, head for that and fish in the area! Failing any of that, I would opt for a shore that has hills, valleys, ravines, cliffs, caves, or is heavily wooded, with trees of uniform height – any or all of the above.. Getting into a cave, or to one of those low spots on land is better than sitting in open water, under a boat slip or bridge. The lake is surrounded by grassy meadows, farm land etc. etc. Now what? Well, land is safer than water, low exposed land is better than high exposed land, so I’d look for the low spot like a ditch.
OK, I am still fishing but have moved closer to one of these safer areas of land. The storm get closer and thunder can be heard and lightning can be seen. I waste NO time dropping that 100% graphite lightning rod – I mean fishing pole, and head for the beach, and the structure I had planned to weather the storm in / on. If not in a substantial building or a vehicle, and the storm is right on me, I get low, knees and forehead touching the ground, hands clasped behind my neck, with my butt the highest part of my body.. I would rather get hit in the butt than the top of the head! If the storm is near but not right on top of me, I would probably opt to just squat down.
Places to avoid are exposed hilltops, single trees on top of a hill, or a single large tree among many shorter ones, small sheds, metal fences, pipes, railroad tracks.
But these were the best of circumstances. Let’s say you’re fishing a hump in the middle of the lake and a storm comes out of nowhere and there’s thunder and lightning all around. Now what? This is a tough call for sure. Run or stay where you are? Obviously it depends on the severity of the storm, the frequency and proximity of the lightning strokes. It would also depend on the apparent strength of the E field. I was caught once, while hiking and could feel the hair on my arms sticking straight up - static caused by the strength of the E field. If I felt that in the middle of the lake, I would opt not to run. I would get to the bottom of the boat, knees and forehead touching the floor, hands clasped behind my neck, making sure my butt was the highest part of my body! I read a recent post on the “Other Topics” board where “neal” was on the lake and could see / feel his rod tip vibrating and saw his line lift off the water a bit as a storm came through. I have never felt or seen that, but don’t discount the validity of those statements – he must have been in one hellofa E field!
To put it in the form of some rules that I follow:
Inclement or unstable weather is a fact of life we have to live with as outdoor people. Fishing in the rain is no big deal, it doesn’t bother me in the slightest and it never stops me from going to the lake. But when I’m out on the lake looking at an approaching storm, more than anything else, common sense sounds the planning alarm. Does it LOOK bad? Does it SOUND bad? Is it moving left to right – right to left? Towards me or away? Just a little proactive planning goes a long way. We all know how difficult it is to leave the lake, especially during a tournament, but storms containing lightning are typically here and gone fairly rapidly. Get off the darn lake if that lightning storm is going to hit you. Once it passes by, allowing some grace period, get back on the lake. I don’t want to read another one of those posts about someone (YOU for instance) having been killed by lightning while bass fishing.
by John Sacchetti
This is the time of year when hundreds of thousands of us begin spending a lot of time on the water. It is also the time of year when violent, sometimes unexpected sudden storms roll through the area. My purpose in writing this report, perhaps in part, is to scare you into the reality that being caught in a lightning storm while on the lake could be the last thing you’ll be caught doing. But more than that, my purpose is to share what I do when caught by a storm, and my understanding of the consequences of staying on the lake, so that you can make an informed decision as to what to do.
"Lightning tends to move at will, bouncing, ricocheting, hopping from place to place. Hopefully you're not in the path or touching that which it bounces to."
Published on River Smallies.com with permission
John "Backlash" Sacchetti resides in SC and can be contacted at Backlash4@aol.com.