500,000 volt current flows in the air Movie

It is like a thunder and electricity flows in the air. It is just a scene of manga.

Details are as follows.500 kV Switch Opening - Google Video

A pattern that was discharged into the air by opening a switch carrying a high voltage current of 500,000 volts.

There is also a movie tried with 345,000 volts.
345 kV Switch Opening - Google Video

What kind of experiment is this ...?