Terry’s Take: Lightning, an illuminating force
Did you know that at any given moment, there are 1,800 thunderstorms in progress somewhere on Earth? This amounts to 16 million storms a year! In the United States, there are an estimated 25 million cloud-to-ground lightning flashes each year. While lightning can be fascinating to watch, it is also extremely dangerous and highly underrated as a killer. In fact, on average more people have died from lightning strikes than hurricanes over the past 30 years.
According to statistics kept by the National Weather Service, the 30 year average for lightning fatalities across the country is 61. Lightning usually claims only one or two victims at a time, and because lightning does not cause mass destruction, such as from a tornado event or a hurricane, lightning generally receives much less attention than the more destructive storm-related events. Due to under reporting, it is estimated that, more realistically, about 100 – 120 deaths per year occur because of lightning. Documented lightning injuries in the United States average 300 per year; however undocumented lightning injuries are likely much higher.
In Iowa there have been 72 deaths attributed to lightning from 1959 – 2012 while in Illinois the number is even greater at 101.
The formation of ice in a cloud appears to be a very important element in the development of lightning in a storm. The collision of ice and water particles causes separation of the positive and negative electric charges in the particles. Positive charged ice particles tend to collect in the upper parts of the storm, with negative charged particles in the middle and lower parts of the storm. These opposite charges attract, thus “in-cloud” lightning is often produced.
As the negative particles gather at the bottom of the storm cloud, a pool of positively charged particles gather along the ground and travel with the storm. As the differences in charges increase, positively charged particles rise up taller objects such as trees, houses, and even people. If you are near a storm, and your hair stands on end, the particles are moving up you! The negative charged particles extend down from the cloud in “steps” and form a step leader. When it gets close enough to the ground or a tall object filled with positive particles, a channel is formed and an electrical transfer takes place. There can be several “strokes” which you see as flickering light. The channel heats to about 30,000 degrees Fahrenheit!. The rapid expansion of the heated air around the channel breaks the sound barrier, and you hear thunder. By the way, one lightning stoke can generate between 100 million and 1 billion volts of electricity! Now that’s what I call an illuminating force.