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| LIGHTNING! When should you be concerned |
| By Don Kopp former fire forester | 06/06/07 |
| It's important to be safe outdoors especially when the threat is present. |
Jon Mitzel’s article on lightning in the August ‘03 issue was informative and timely. It’s possible that someone may escape serious injury or even death because of his or her willingness to share an experience with readers of Dakota Country.
There seems to be a misconception among some people that lightning doesn’t strike water or people on the water. If my memory serves me right, it was during the mid-to-late 80’s that three men were fishing on Sheridan Lake. A small thunderstorm began to develop over the Pactola watershed approximately 10 miles north of where the three were fishing.
According to eye witnesses who were also on the lake, a bolt of lightning “out of a clear blue sky” flashed down, striking one of the men who was standing ( it was also reported tthat htis man had a graphite fishing rod) in the boat, instantly killing him and the man next to him.
The same bolt seriously burned the third man who was sitting toward the aft end of the aluminum boat.
Many people are oblivious to the fact that every year in this country, lightning strikes kill twice as many people than do tornadoes, hurricanes, and flash floods combined. Before I retired from the South Dakota Division of Forestry, I witnessed, on several different occasions, lighting strikes that killed 18 to 20 head of livestock with one single bolt. In one instance, lightning struck a wooded meadow east of Sturgis, killing 18 head of livestock and starting a timber fire. In another instance, a man was killed on Skyline Drive in Rapid City while watching helicopters drop water on a nearby forest fire, and that very same day, 15 miles north in the Piedmont area, a firefighter was injured by lightning while working another fire. Very possible from the same bolt, since the time each person was hit, very closely coincided.
Lighting is the second leading cause of forest fires in the United States and Canada. It also does millions of dollars worth of every year to various electrical components not to mention structures that are stuck and are burned to the ground. Benjamin Franklin is indeed extremely lucky to have survived his kite and key experiment.
Obviously, lighting does not come from a “clear blue sky”. This, of course, is impossible. Yet clouds many miles away can and do generate enough of a charge to flash across 10 or 20 miles from their position and if lightning is detected, should seriously consider getting off the water.
Lightning storms, of course, are never invited, never planned and never go unnoticed, they are the most powerful display of electrostatics in nature, and mankind throughout history has wondered, most in trepidation, but always in an almost reverent respect of its awesome display of power.
So what is lightning anyway and how is it generate?
Since lightning starts many forest and range fires every year, it was part of my job to know a little bit about it and how it works.
First, there are three types of lightning discharges. One is cloud-to-ground, ground-to-cloud and cloud-to-cloud. Lightning strikes generally happen in about 1/10,000/second, and approximately half of all strikes are ground-to-cloud. It’s now known that these (ground-to-cloud) strikes are the ones most responsible for starting wildfires and killing people since they are positively charged, while cloud-to-ground strikes are negatively charged or, as we used to call them, “Cold bolts.”
The production of lightning requires a thunder cell to attain an altitude of at least 28,000 feet. At this elevation, water particles (vapor) are turned to ice because of the extreme cold at that height. The frozen particles are then thrust into the jet stream or other high wind source. The wind dragging your foot over the carpeted floor in the living room. Since the temperature at that altitude is extremely cold, the air is very dry. Supre dry air, as you know makes ideal conditions for static electricity.
As a thunderstorm develops, regions of negative electric charge form along the base os the clouds, which in turn causes positive charges to build up along the ground. Thus, as the cloud moves over the surface of the earth, it drags along with it an invisible cloud of positively charged particles on the ground. This invisible cloud climbs church steeples, trees, tall buildings and yes, graphite fishing rods. It’s this invisible cloud of positively charged particles that make your hair stand up or as Jon Mitzel described it: “We could hear the buzz of electricity through our graphite rods...”
Graphite, as Jon already pointed out, is an excellent conductor of electricity.
However, we still need one more element to complete the discharge of static electricity to the ground or visa versa. A conducting link, like an electrical cord has to be established between the cloud and the ground through which the electricity can travel, since the gases making up our atmosphere are a good insulator and will not readily conduct electricity. Fortunately for young Jon, his graphite rod wasn’t the missing link... at that point anyway.
As the cloud builds its charge, so in unison will the invisible cloud of particles on the ground continue to build and amplify in strength. Eventually the field between the two will become so strong that the air between them is ionized and a pathway of gas called “plasma” is formed. This ionized pathway is the conductor, which the electricity is discharge.
It wasn’t until the mid 1980’s that this pathway, called “a step leader” was actually photographed usnig extremely high-speed photographic equipment with a special film highly sensitive to electromagnetic fields. The formation of the step leader is so rapid the human eye cannot see it, only the blinding results of the white-hot discharge through the pathway is observed. The speed at which the actually discharge occurs has been measured at more than 40,000 miles per second.
I think it is also guite interesting to note, that while we just discovered the secret of how lightning is conducted through this pathway we call a “step leader”, 4,000 years ago, God asked Job this question: “Who has divided a channel for the overflowing of water, or a pathway for the lightning?”
Job 38:25. • |
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