Go Fly a Kite!

Imaginative drawing of Ben Franklin and his kite.

June 15, 1752: Benjamin Franklin’s kite flying experiment proves lightning and electricity are related. Maybe. The account of Franklin’s experiment wasn’t written down for another 15 years when the tale was placed into Joseph Priestley’s History and Present Status of Electricity. While the idea of old Ben standing out in a storm with a kite floating in the ominous sky, key attached, and the scientist in grave danger is pretty standard, if he did perform the experiment at all, he did not put himself in the path of danger.

Franklin did write much about his fascination with electricity and his premise stating lightning was made of the same energy. At the time, the largest electrical sparks to be generated were about an inch long. To take the giant leap from small spark to the outrageously powerful lightning strike being the same would take some proof. Franklin’s ideas about the phenomenon led him to experiment, but with an intermediary collection device. A Leyden Jar, or capacitor, was used to collect the energy discharged during a lightning strike. Although he did not put himself in the direct line of fire, other experimenters did and died as a result.

Lightning is, in fact, an electrical discharge. It usually occurs during thunderstorms, but can also follow volcanic eruptions and dust storms. Lightning is powerful, moving at speeds up to 130,000 mph and reaching temperatures nearing 54,000° F. This is hot enough to melt silica, turning sand into glass. What we know is when there is enough energy buildup, there is an electrical discharge with a bolt of lightning running either between clouds or from clouds to ground.

Thunder is the audible result of the lightning bolt. During a lightning strike, successive parts of the air are used as a discharge channel. The area superheats along the discharge channel and then the air rapidly expands. This causes a shock wave which we hear as thunder. The rumbling variety is caused by the time delay between the sound of different portions of a long strike. There are ≈ 16 million thunderstorms each year around the globe. With this many storms there are about 1.4 billion lightning flashes per year with 80% of them cloud to cloud and the rest ground strikes. That means 280 million times a year, lightning strikes. It is not evenly distributed around the globe, with 70% of all lightning occurring in the topics.

Electricity is really just organized lightning. – George Carlin

I’d rather be a lightning rod than a seismograph. – Ken Kesey

Television news is like a lightning flash. It makes a loud noise, lights up everything around it, leaves everything else in darkness and then is suddenly gone. – Hodding Carter

The reason lightning doesn’t strike twice in the same place is that the same place isn’t there the second time. – Willie Tyler

Also on this day:

King “Soft-sword” John “Signs” on the Dotted Line – In 1215, King John of England signs the Magna Carta.
Not Spock – In 1844, vulcanization was patented.
Protect Your Eyes – In 763 BC, the first total solar eclipse was recorded.