Ball lightning that melted 7cm hole in window glass in 1976

[Minich]

Input data:

window glass thickness: 3mm
ball lightning diameter: 10cm
discharge duration 30 seconds

After the discharge there was 7cm round hole in the window glass (after freezing to atmosfere temperature).

It was a real case in 1976 year in Frijazino city, near Moscow during school lesson.

 

[gareth]

a rough estimate would be to calculate the energy needed to vaporize the said volume of commen glass.

Calculate the volume, then find the vaporisation energy required for the glass.

In reality, I'm sure it was not purely vaporised, but a mixture of molten glass and glass vapor. In this case reproduce the said calculation with 50% liquid and 50% vapor.

A rough estimate but will give you an idea.