The acidity of precipitation is measured on a pH scale, ranging form 0 to 14, that measures acidity and alkalinity. Increasing acidity is represented by numbers less than 7, while rising alkalinity is represented by numbers greater than 7.
All rainfall is acidic due to natural causes.
Normal rainfall has a pH of between 4.8 and 5.4. Once in the atmosphere, these Gas es react with other chemicals to form sulfuric acid and nitric acid. The acids can return to the earth as gases or particles, or in rain, snow, or fog. In industrialized areas, the vast majority of sulfur and nitrogen emissions are from human activities primarily the combustion of Coal and Oil .