How can I clean ‘acid rain’ spots from my window?

Use a razor blade scraper to get the crust off.

You might try glass stove top cleaner for the storm door if nothing else has worked. It works amazing on our shower door when it gets really bad. It's great at taking off buildup that seems permanently "stuck on!"

dawn dish soap, baking soda mix into paste scrub with new stiff toilet bowl brush( easier to reach) then add vinegar-fizzing- scrub again let solution sit on any mineral deposits/acid rain spots then scrub some more rinse with boiling water or as hot as possible. then do glass

straight rubbing /isopropyl alcohol and clean wash cloth( no fabric softener on it and no paper towels both cause streaking and smearing)--just pour alcohol on cloth and wipe glass,mirrors,auto glass;do inside one direction-horizontal and other side -vertically this way you can tell easier which is not clean. Preventing Acid Rain Corrosion

Get your house windows/car washed on a regular basis. If you prefer not to spend the money and time to consistently get it washed, wash your windows immediately after it rains or snows. The more immediate the cleaning, the more likely you are to eliminate acid rain before it seeps into the pores of the glass or paint. Remember to always thoroughly dry your homes windows/vehicle (including windows) after washing it. Applying a coat of wax regularly is also highly recommended to avoid spots on your paint.acid rain & mineral deposits can permanently etch the glass/paint so if youblive in densely populated city with high industry washing cleaning regularly is important.