Composition of acid rain
... Rain Acid rain or acid precipitation is the "atmospheric deposition of acidified rain, snow, sleet, hail, acidifying gases and particles, as well as acidified fog and cloud water" (Likens, 2007). It also refers to precipitation that is much more acidic than natural, unpolluted rain.
Measurement of Acid Rain
"The pH scale is used to measure the acidity or alkalinity of an aqueous solution and is determined by the hydrogen ion (H+) content" ("Measuring Acid Rain"). This scale ranges from 0 to 14, moving from strongly acid to strongly alkaline, respectively, with the point 7 representing neutral.
(source: Environment Canada)
"The pH scale is logarithmic rather than linear" ("Measuring Acid Rai...