Acid rain

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Effects of acid rain

Learn about the causes and effects of acid rain

Diagram illustrating the nitrogen cycle, showing how nitrogen moves between the atmosphere, biosphere, and soil through natural processes like nitrogen fixation, assimilation, ammonification, nitrification, and denitrification, as well as through human activities such as fertilizer use and industrial emissions. Blue arrows indicate natural activities, and red arrows indicate human activities.

Diagram illustrating the sulfur cycle, showing how sulfur moves through the biosphere and atmosphere. Arrows trace sulfur emissions from fossil fuel burning and decomposition, deposition from the air, plant uptake, runoff into water, and sediment formation.

Two pie charts compare sources of sulfur dioxide and nitrogen oxides emissions contributing to acid rain. The first chart shows electric utilities produce 66% of SO2, other sources 29%, and vehicles 5%. The second chart shows vehicles produce 58% of NOx, other sources 24%, and electric utilities 18%.

Severely defoliated spruce trees stand amid snow in Karkonosze National Park, Poland.

World map highlighting regions with high acid sensitivity in orange and areas of acid deposition with purple hatching. Notable high sensitivity regions appear in eastern North America, northern and central Europe, parts of South America, Africa, and Asia, with some overlap between acid sensitivity and deposition zones. Continents and major oceans are labeled for reference.

Weathered statue with a damaged face and surface, showing significant erosion from acid rain and pollution.

Learn how pollution from industrialization in Europe damaged the limestone of Cologne Cathedral

Line graph showing U.S. emissions of ammonia (NH3), sulfur dioxide (SO2), and nitrogen oxides (NOx) from 1970 to 2008. SO2 and NOx emissions decline steadily, while NH3 remains nearly constant. The graph relates to acid rain.

At a Glance

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acid rain summary

Acid rain: Media

pollution

Videos

Learn about the causes and effects of acid rain

Learn about the causes and effects of acid rain

When gases emitted by motor vehicles and industrial processes encounter clouds, the...

Video: Created and produced by QA International. © QA International, 2010. All rights reserved. www.qa-international.com

Learn how pollution from industrialization in Europe damaged the limestone of Cologne Cathedral

Learn how pollution from industrialization in Europe damaged the limestone of Cologne Cathedral

Repairing acid rain damage to Cologne Cathedral.

Video: Encyclopædia Britannica, Inc.

Discover how researchers sample clouds for acidity and pollution caused by industrial and automobile emissions

Discover how researchers sample clouds for acidity and pollution caused by industrial and automobile emissions

Sampling clouds for acidity at Whiteface Mountain, New York.

Video: Encyclopædia Britannica, Inc.

Visit Germany's Black Forest to study the effects of industrial emissions, urban smog, and acid rain

Visit Germany's Black Forest to study the effects of industrial emissions, urban smog, and acid rain

Testing rainwater and air for acidity at a research station in the Black Forest,...

Video: Encyclopædia Britannica, Inc.

Images

Effects of acid rain

Effects of acid rain

Forest dieback caused by acid rain in the Jizera Mountains, Czech Republic.

Nipik

Diagram illustrating the nitrogen cycle, showing how nitrogen moves between the atmosphere, biosphere, and soil through natural processes like nitrogen fixation, assimilation, ammonification, nitrification, and denitrification, as well as through human activities such as fertilizer use and industrial emissions. Blue arrows indicate natural activities, and red arrows indicate human activities.

nitrogen cycle

The nitrogen cycle.

Encyclopædia Britannica, Inc.

Diagram illustrating the sulfur cycle, showing how sulfur moves through the biosphere and atmosphere. Arrows trace sulfur emissions from fossil fuel burning and decomposition, deposition from the air, plant uptake, runoff into water, and sediment formation.

Sulfur cycle in the atmosphere

Diagram of the sulfur cycle, showing how sulfur moves between the atmosphere, the...

Encyclopædia Britannica, Inc.

Two pie charts compare sources of sulfur dioxide and nitrogen oxides emissions contributing to acid rain. The first chart shows electric utilities produce 66% of SO2, other sources 29%, and vehicles 5%. The second chart shows vehicles produce 58% of NOx, other sources 24%, and electric utilities 18%.

SO₂ and NO_x emissions in the U.S.

SO₂ and NO_x emissions in the U.S., 2008.

Encyclopædia Britannica, Inc.

Severely defoliated spruce trees stand amid snow in Karkonosze National Park, Poland.

The visible effects of acid rain on spruce trees.

Spruce trees damaged by acid rain in Karkonosze National Park, Poland.

Simon Fraser—Science Photo Library/Photo Researchers, Inc.

World map highlighting regions with high acid sensitivity in orange and areas of acid deposition with purple hatching. Notable high sensitivity regions appear in eastern North America, northern and central Europe, parts of South America, Africa, and Asia, with some overlap between acid sensitivity and deposition zones. Continents and major oceans are labeled for reference.

map of acid deposition

Areas affected by acid deposition contrasted with regions of high acid sensitivity.

Encyclopædia Britannica, Inc.

Weathered statue with a damaged face and surface, showing significant erosion from acid rain and pollution.

acid rain

Statue eroded by acid rain.

© Julius Fekete/stock.adobe.com

Line graph showing U.S. emissions of ammonia (NH3), sulfur dioxide (SO2), and nitrogen oxides (NOx) from 1970 to 2008. SO2 and NOx emissions decline steadily, while NH3 remains nearly constant. The graph relates to acid rain.

Sulfur dioxide, ammonia, and nitrogen oxides emissions in the U.S. between 1970 and 1985.

U.S. emissions of SO₂, NO_x, and NH₃, 1970–85 (five-year...

Encyclopædia Britannica, Inc.

Color-coded map of the contiguous United States showing the annual pH of precipitation weighted by volume in 1994. The western and central regions are shaded in green, indicating higher pH values (less acidic, generally above 5.0), while the eastern United States is shaded in orange and red, representing lower pH values (more acidic, below 4.6). Specific pH values are labeled at various locations, with the lowest pH levels concentrated in the Northeast and parts of the Midwest.

precipitation pH in the United States, 1994

Map of precipitation pH in the continental United States in 1994.

Encyclopædia Britannica, Inc.

Color-coded map of the contiguous United States showing the annual pH of precipitation in 2008, with values ranging from 5.3 and above in the West (green shades) to below 4.5 in parts of the Northeast and Midwest (orange and yellow shades), indicating more acidic precipitation in the eastern regions. State boundaries and major pH measurement points are marked throughout the map.

precipitation pH in the United States, 2008

Map of precipitation pH in the continental United States in 2008.

Encyclopædia Britannica, Inc.

Line graph of hydrogen ion concentration in Hubbard Brook precipitation from 1963 to 2007, declining overall from about 75 to 30 equivalents per liter, with a peak near 95 in 1970.

Freshwater acidification at the Hubbard Brook Experimental Forest.

Graph of hydrogen ion concentration in water collected at Hubbard Brook Experimental...

Encyclopædia Britannica, Inc.

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