I am in the business of linings for flue gas desulfurization units for power plants ("acid-rain" removal stuff), so I think I have some perspective on this.
Unless you live a few miles downstream from a dirty coal burning coal-fired power plant, I would highly doubt acid rain is the culprit.
By the way, glass is pretty resistant to acidic condensate - think test tubes and beakers.... What happens most often is the paint gets damaged, and the utility buys you a new paint job. Glass, however - no.
As for a fix to your glass problem - not my area. Cheers
