With summer officially here we have already had some scattered thunderstorms in the area. I guess that means it’s time to review what we know about this potentially deadly weather event. A lightning bolt can be as hot as 54,000 degrees F. with an average peak current of 30,000 amperes, and produces 500 megajoules of energy.
Since I grew up in Upstate New York I was quite accustomed to the sound of thunder and the bright flash of lightning. Sometimes I actually miss thunderstorms with their rain pounding on the roof in waves and a bright flash of light followed closely by the loud crack or rolling thunder. I remember counting the seconds between the flash and the crash. Count the number of seconds, divide by five, and you get an approximation of how many miles away the strike was from your location. Using that as a measurement the closest I ever was to a lightning strike was about a quarter mile in Eau Claire, WI. That time my wife and I saw the flash and almost immediately heard the thunder crash so loud that it shook the window in the room and we both hit the floor at the same time.
The closest lightning strike for me here in Eugene occurred on July 12, 2009 when a tree in a cemetery less than a mile from my house was struck and literally exploded into many pieces blowing the top off.
Now that we’ve seen the power lightning has I think it would be a good idea to explore what it takes to produce those dangerous but often beautiful lighting bolts that can crisscross the sky. Lightning is usually formed in a cumulonimbus cloud or thunderhead. It is the result of a build-up of electrical charges within the cloud. The upper part of the cloud which reaches into the colder part of the atmosphere forms ice crystals that are usually positively charged. Raindrops form in the lower portion of the cloud and they contain a negative charge.
As the cloud moves over the land the negative charge at the bottom of the cloud induces a positive charge at or near the surface. As you’ve heard many times before opposites attract and an electrical charge builds between the bottom of the cloud and the surface or something standing on the surface like a building, tower, or even a person standing outside. A leader comes down from the cloud toward whatever it is attracted to and an upward streamer moves from the object up to the cloud. When they meet the path to the ground is completed. A return stroke then follows the path back up to the cloud at an outrageous speed of 60,000 miles per second. That’s what forms the bright flash. The flash is actually moving from the object upward even though your eye sees it as striking down from the cloud. The noise of the thunder comes from he rapid heating and cooling of the air (expansion and contraction) around the lightning bolt.
Lightning displays can be beautiful, especially at night, but they can also be deadly. We should be thankful that there are four major categories of clouds: within-a-cloud, cloud-to-cloud, cloud-to-air, and cloud-to-ground. If all we had were cloud to ground lightning strikes people all over the world would be constantly ducking and weaving to keep away from the deadly electrical charges. Many people have studied lightning but Benjamin Franklin is probably the best known. His key on a kite string experiment was performed to prove that lightning was naturally occurring electricity. He did get shocked during one of his experiments and I have heard that some scientists say Franklin was very lucky he didn’t get electrocuted flying his kite with the key on the string.
Others who have tried to duplicate Franklin’s experiment have reportedly been electrocuted and I have heard they died trying. I know of a true story that happened in the Midwest. A farm worker loved flying kites, but he got tired of constantly having to replace kites lost when the string broke in the wind. So, “Mr. genius” decided to use a large spool of industrial strength copper wire figuring it was much stronger than string and he would never lose a kite again. Well, he used his copper wire and ran it out so the kite was so high he could hardly see it. I’m sure you already figured out what comes next. Lightning struck his kite, followed the copper wire down to his hands, and instantly electrocuted him. His death reminds me of my favorite quote from the movie Forrest Gump “Stupid is as stupid does.”
Lets clear up some myths about lightning. Lightning never strikes twice in the same place. Wrong. If the target still stands it can be struck again and quite often is. As long as you stay inside during a thunderstorm you are safe from lightning. Wrong. Lightning has been known to strike people through windows and it can strike a telephone, cable, or power line and follow it into your house through the wire. A neighbor of mine in Memphis, TN, more than twenty five years ago, had a bolt of lightning strike the power line into the house and burned the inside of their dishwasher, fried the toaster, and blew out the microwave oven all of which were connected into the same circuit. Here in Eugene while working as Chief Meteorologist for KVAL-TV lightning struck the TV tower and blew out all of the computers in the building along with their connections to the news control room. My weather computers were not harmed and I was a bit cocky about mine being the only ones not knocked out. About an hour later I realized mine did work, but I had no new data coming. That was also the day that one of the communications satellites died blacking out a lot of medical pagers and other devices. That just happened to be the satellite that transmitted data to my weather computer system. Lesson learned. Don’t make fun of someone else’s problem because it just might become your problem too. There were, incidentally, only two booms heard which means only two possible strikes occurred, but at least one of them caused a lot of damage. There are other ways to produce lightning. Dust storms and wild fires can produce the elements needed to produce lightning and another example is the eruption of Mt. St. Helens on May 18, 1980.
If you feel the hair on your neck stand up while outside and a storm is nearby you need to immediately crouch down. That way you are a smaller target and if you do get struck the charge would pass through your body more quickly, hopefully doing less damage. Is a car a safe place to be in a thunderstorm? If you can’t get to a building a car is a relatively safe place. Don’t touch any metal inside and the metal shell of the car will shield you. The same goes for being a passenger in an airplane flying in or near a thunderstorm. Most of the strikes to the body of the plane have no effect, but a strike to one of the engines could do some serious damage. If you are inside a building remember to stay away from windows and stay off the telephone or any electrical equipment as long as the storm is near you. Can lighting effect more than one person at a time? It certainly can. During a baseball game a thunderstorm built up and lightning struck the pitcher. The lightning continued along the ground and knocked down the entire infield. There is one man, Roy Sullivan, who is in the Guinness Book of World Records for being struck 7 times (from 1942 until 1977) and lived to tell his story.
If you can hear thunder or see even the glimmer of the lightning in the distance you are at risk for being struck. Stay indoors until the storm is well away from your area. Just in case you were wondering, the odds of being struck by lightning are computed to be 1 in 10,000. I’ll bet Roy Sullivan would have some choice words to say about that. Be safe out there.
Let me know what you would like me to talk about or explain. You can comment below or email me at: [email protected].