Glossary of Global Warming and Climate Change Terms

Sulfur dioxide and nitrogen oxides are the primary causes of acid rain. In the United States, about two thirds of all sulfur dioxide and one-quarter of all nitrogen oxides come from electric power generation that relies on burning fossil fuels like coal. Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. These acidic compounds fall to the earth as acidic rain, fog, and snow, or as dry deposited gases and particles that can be blown to the ground by the wind. In fact, prevailing winds can blow the compounds that cause acid rain across state and national borders, and sometimes over hundreds of miles.