One evening in late April this year I discovered a shattered tree in the woods behind my house that I decided must have been struck by lightning. The 8-inch diameter black locust tree trunk was snapped off five feet above the ground. The upper portion was split apart exposing the heartwood. The branches leaning on a nearby tree were blackened, suggesting to me they were burned. The felled portion of the tree was leaning in the direction of prevailing winds, so something else besides wind was responsible for toppling this tree. A week later, I discovered a 3-inch wide vertical split in the bark of a 50-foot black walnut tree in my side yard extending from the ground to the highest branches. Was this a second tree struck by lightning, perhaps during the same thunderstorm?
As a teenager, I recall feeling a jolt from lightning when my dad asked me to clean winged maple seeds from the gutter on our patio roof during a rainstorm. After a flash of lightning, I felt a surge of electrical current from the gutter into my hand similar to touching a plugged in damaged electrical cord. I was thrown several feet backward off the step ladder, startled but safe. These close encounters with lightning aroused my curiosity.
Thunderstorms are actually a misnomer and should be called lightning storms because lightning generates thunder. Lightning rapidly heats air to a million degrees causing air to expand creating a loud crack just like the loud pop heard when a balloon is punctured allowing air compressed inside to escape rapidly. It is known thunderstorms form warm moist air rising to create a huge cloud often 50,000 feet in the air. The moisture condenses and forms water droplets which are lifted up further by warm air below. Temperatures at the top of the cloud can be minus 30 degrees Fahrenheit, similar to temperatures outside a commercial jet flying at 35,000 feet. Friction and turbulence of air molecules, ice crystals and rain drops generate a positive electrical charge at the top of the cloud. A negative charge develops at the base of the cloud. For reasons not completely understood, the earth has a perpetual negative charge. The negative charge at the base of the thundercloud repels the negative charges on earth just under the cloud, allowing positive charges to creep up to the top of trees, hills and buildings. Positive and negative charges attract each other, but since air is a poor conductor of electricity the charges remain apart building to huge potentials until they "jump together," creating a spark which is a bolt of lightning maybe thousands of feet long from cloud to ground.
This tree in the woods behind the author’s home appears to be split apart by lightning.
Photo by Robert M. Ungerer
Interesting facts about lightning include:
Lightning bolts generates a million volts of energy but just for a fraction of a second and heat five times hotter than the sun.
The Empire State Building is struck by lightning on average 23 times a year.
There are 1,000 thunderstorms in progress on the planet every moment with lightning striking the earth 100 times every second.
Since the sound of thunder travels 1000 feet per second, one can determine the proximity of a lightning strike by counting the number of seconds between the flash of lightning and the first sound of thunder then multiplying the seconds by 1000 feet to get the distance in feet.
The continuous rolling sound of thunder occurs since the sound of thunder at the base of the cloud takes longer to reach our ears than the sound at the ground site.
To be safe during a thunderstorm:
Seek shelter in a building or motor vehicle.
If unable to get inside, seek a low area like a ravine or ditch.
Avoid standing under a tree. Trees attract lightning.
If in a group, separate from each other.
Stay away from standing water.
Remove metal jewelry and wrist watches.
Lightning is a familiar phenomenon to most people in the world. We like to watch lightning from a distance because we fear and respect it.