Today, pollution is the most serious problem of the earth. Acid rain is the one of the most important pollution. So it has remained largely undetected even in the areas where it has been falling for many years.
Acid rain is a complicated problem, but it is mainly from air pollution.
Scientists have discovered that air pollution from burning of fossil fuels is the major cause of acid rain. The main chemicals in air pollution that create acid rain are nitrogen oxides and sulfur dioxide. Acid rain usually forms in the clouds where sulfur dioxide and nitrogen oxides react with water' oxygen, and oxidants. This forms a mild solution of sulfuric and nitric acid. Besides rain, snow, fog and other forms of precipitate containing these mild acids fall to the earth are all called acid rain.