How is Acid Rain Formed

By Kylene Arnold
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The gasoline in your vehicle produces more than energy as you drive to work each day. Coal plants create more than electricity to power homes and businesses. Burning gasoline and coal releases some not-so-wonderful noxious chemicals into the atmosphere. Although natural processes also produce small amounts of these chemicals, unchecked fossil fuel emissions can significantly raise the levels and cause a phenomenon called acid rain.


Acid rain primarily comes from sulfur dioxide and nitrogen oxides, which are released into the atmosphere through volcanic eruptions, organic decay and fossil fuel emissions. Fossil fuels are the highest concern because they are released rapidly and regularly into the air. Energy plants, factories and vehicles are the main culprits of acid rain, especially in densely populated industrial areas, such as the Northeast U.S.

Chemical Reaction

When sulfur dioxide and nitrogen oxides escape into the air, some of these compounds react with water, oxygen and other chemicals to form sulfuric and nitric acids. These chemicals fall back to the ground as acid rain, which can have a pH level of 4.3 or more. This is over 500 times more acidic than pure water and 20 times more acidic than normal rain.

Wet Deposition

Acid rain is a general term that includes any kind of contaminated precipitation, including rain, snow and fog. Environmentalists call this wet deposition. As the moisture reaches Earth, it changes the acidity of soil and standing bodies of water, harming plants and animals. Over time, it can even damage buildings, statues and vehicles.

Dry Deposition

Arid regions are not exempt from acid rain. Sulfuric and nitric acids combine with dust, smoke and smog and settle to the ground. When it rains, these particles are washed into rivers and lakes, creating the same effects as acid rain. Environmentalists call this dry deposition.

About the Author

Kylene Arnold is a freelance writer who has written for a variety of print and online publications. She has acted as a copywriter and screenplay consultant for Advent Film Group and as a promotional writer for Cinnamom Bakery. She holds a Bachelor of Science in cinema and video production from Bob Jones University.