Lightning

A couple of weeks ago my fire brigade attended a grass fire only 4 km from Piora. So we got there with our truck and circled it fairly quickly using air blowers. A big log kept burning somewhere in the middle and that was put off with water and foam, thanks to the help of the local farmer and his tractor who turned it over for us.

A funny looking hole was found in the middle of that and one of my firies mates said this could well be caused by the lightning strike that started all this. Indeed electrostatic repulsion can move things, but is that enough to dig a hole?

What causes lightning? It all starts with a strong temperature difference between two air masses within a cloud. The hot air goes up, the cold air down. The friction between the cold and hot air creates static electricity, so we end up with a positive charge at the top of the cloud and a negative charge at the bottom. When the voltage gets high enough, sparks form within the cloud, or between the base of the cloud and the ground.

A lightning strike is very narrow, about 3cm only. But the temperature in there suddenly increases by about 30,000 degrees C. The pressure and volume increase about 100 times in a millisecond. This is what we call an explosion. Things get thrown around and there is a loud noise.

Reference: this excellent Kiwi site explains it all for you

https://www.sciencelearn.org.nz/resources/239-lightning-explained