What is that sound coming from transmission lines in monsoon?

That hissing sound is due to an effect called Corona effect. Yes, we electrical engineers are dealing with this corona since the birth of long range high power transmission line. It is due to the ionization of the air near to transmission lines. Due to rain ionization increases due to moisture in air. So next time if you hear these things make sure you grab a thermal camera to enjoy it's beauty. It would be a faint violet color.

#THEWATT