Many years ago, at age 10 or so, I was flying a kite on the beach on what I recall as a foggy or misty day. It would have been in the early spring. The kite couldn’t have been very high, certainly under 100’. From time to time I would get a shock from the wet kit string. Not a knock-you-down shock but enough to scare me. Also, if my memory is correct, the sand around me would occasionally “pop” like someone had shot a bb at it from above but more like a tiny explosion just beneath the surface of the dry sand. I do know it wasn’t actually raining (but almost) and it was not typical thunderstorm weather. It was a cool wet day. What was going on here?
As you surely must have surmised, this sounds a lot like Benjamin Franklin’s famous kite experiment.
Unlike the usual way this is imagined, Franklin didn’t fly his kite in an active thunderstorm, and his kite wasn’t struck by a bolt of lightning. He did fly it in a cloudy sky and got a static charge on the line (wet packthread was a common conductor for those early experimenters).
You might have been lucky – some others who repeated Franklin’s experiment did have their kites struck by lightning, and got killed.
Static electricity? It’s in the air. Under the right conditions it might build up on the string. Just like walking on carpet and touching another person. Or clothes in the dryer crackling when you pull them apart.
There are cases where people got knocked on their ass by touching an metal cupola on a roof. There is an average potential of around 30V/foot in still air, so just having an insulated metal object 100ft in the air will charge it to 3,000V. Adding a stiff breeze can increase that substantially.
Misread this as “clothes in the dryer cackling”. Usually, that only happens to me when I put vinyl in there by mistake.
Yep, I thought of Ben Franklin, even at the time. But I didn’t have a key on my kite string (and for all I know, neither did he). I had no idea of the potential of 30V per foot. I was in the Harbor Patrol early in life and I remember them telling us that if we were ever involved in a helicopter rescue to let the basket touch the boat or water first as the static shock would knock you on your ass. There was no lightning at the time but I suppose there is always that first bolt. Any idea on what was going on with the sand? That memory isn’t quite as clear but I’m pretty sure it happened. Maybe critters beneath the surface reacting to getting shocked?
He did, but it’s not essential – it’s a convenient metal object that the charge collects on. Franklin toughed his knuckle to the key to get sparks, and used it to charge his Leyden Jar. But the wet thread will conduct the charge right down to you, key or no.
This is just one example for atmospheric power collection that has been written about for a long time. It’s large scale harvest that hasn’t been done.
yes airflow over an object can leave a static charge on that object.
as stated there is a static voltage just due to height.
The “clear weather potential” is about 300V per meter at max. Most of the leakage takes place at the dampened kite itself, so if your kite is 50M up, the string will charge to 15 kilovolts. It sound like you must have been standing in dry sand, so electric sparks were popping under your feet.
Don’t forget Ben Franklin’s recipe: tie your damp kite string to a silk ribbon, then hold the ribbon. (Or use a piece of dry nylon string.) This allows the kite and string to charge up. Tie a metal key to the string, then let sparks leap from key to knuckle.
Here’s a video where someone tied off their kite to a plastic park bench: