Video here
http://www.katu.com/home/video/100229474.html
If you don’t want to watch the video, the short story is that someone’s chimney was struck by lightning causing the bottom part of it to explode and all the brickwork all the way up is out of place. It shifted hard enough to knock the plaster off the walls it ran inside.
Would it just have been from the extremely quick heating of the air inside the chimney?
whatever path the electrical charge would take would get really hot. the brick and mortar would expand in this path and fracture from the nonheated material.
Even without electrical conduction through materials, the air around a lightning strike heats up enormously as the current discharges though it, which is what actually makes the noise. This hot air creates a pretty strong shockwave that can damage nearby objects to the strike.
Given the overall damage that must have been a monster bolt of lightning.
The cement in concrete has water as part of its crystal structure. High temperatures can cause the water to be driven out of the cement. I suspect the lightning caused this water to turn to steam instantly, causing the bricks to be thrown violently.
During an afternoon thunderstorm, I spoke to my boss in his corner office of a six story office building when a lightning bolt of hit. We both heard a buzzing sound in the wall just before and during the strike with an instantaneous flash and sound of thunder. Next day, my boss stop by and said a back window of a car had been punched out by a piece of the building. So I and a friend went to the top of the building and lo, you could see bare metal on the outer corner of the building; a four inch irregularly-shaped piece about a 1/2 thick had blown off.
Give the concrete stucco (?) would have been saturated from moisture, it didn’t surprise me. But there were no obvious scorch marks on the metal or anything else for that matter.
Within a month, lighting rods had been installed on the top of the building. Perhaps the fact that we had all sorts of antennas on the roof and cables dropping various floors throughout the building had something to do with it . . . :smack:
It would have been raining during the storm which would deliver water to a structure laced with fissures. Chimneys also have creosote in them which would be a source of fuel.
Brick is a lot more porous than many people realize. I discovered this myself recently, with four bricks that appeared dry. They’d been in my Seattle-area backyard for years, so there was plenty of exposure to moisture, but nothing that could be felt or seen. I put them in a bucket with a lid to help stabilize a canopy. After sitting the sun for a day, the inside of the bucket was covered with condensation with maybe a tablespoon or two of liquid down in the bottom. If four apparently dry bricks can hold that much moisture, you can imagine how much the chimney had in it.
Mighta been. There’s “regular” lightning, and then there’s positive lightning, in which the voltage and current levels are far higher than usual.
