What is Acid Rain

Acid rain is polluted rain, snow, or fog. The burning of fossil fuels, base metal smelting, and fuel combustion in vehicles emits sulfur dioxide (SO2) and nitrogen oxides (NOx). These gases enter the atmosphere and transform into sulfuric acid (H2SO4) and nitric acid (HNO3), which then acidify the water vapor. The acidified water vapor will then fall to the earth as acid rain, snow, or fog. This is called ìwet depositionî. There is also ìdry depositionî which falls to the ground in particulate form.