Glossary: Acid Rain

Acid Rain

Acid rain is one of the greatest environmental threats of our time. The formation of acid rain starts in the smokestacks of factories and the exhaust pipes of vehicles. When sulphur and nitrogen oxides are emitted into the atmosphere, they are transformed into compounds. These compounds combined with water vapor in the air form mild sulphuric or nitric acids. They return to earth in acidified rain, snow, fog droplets, dew, and frost, or as dry matter.