pH of rain with and without thunderstorm I just came to know that pH of rain water will be lesser when it is accompanied by a thunderstorm than when it is not accompanied by thunderstorm.
Why would it be so?
Will the temperature increase due to excessive friction (of air) and lighting and thus more ions of water will dissociate reducing the pH?
Or will it be because of production of acids in air during thunderstorm?
Help.
Though I've never heard of that statement before, it's possible that nitrogen oxides formed by electrostatic discharge (not only lightning, but even glow discharge) dissolve in the rainwater, producing nitrous and nitric acids. 

There is a 1997 citation describing comparison of pH in rain accompanied (or not) by lightning.

That said, presence of fly-ash from coal burning, sulfur oxides from volcanic activity and carbon dioxide from natural as well as anthropogenic sources probably have greater influence on pH.