Shop Windows to the Universe

Dig into Montana Before History: 11K Years of Hunter-Gatherers in the Rockies and Plains by D. H. MacDonald, Ph.D. See our online store book collection.
Acid rain damages buildings such as this one in Copola, Mexico.
Click on image for full size
Courtesy UCAR

Acid Rain

Acid rain is a general term used to describe different kinds of acidic air pollution. Although some acidic air pollutants return directly back to Earth, a lot of it returns in rain, snow, sleet, hail, mist or fog, which is why we call it acid rain.

When power plants, factories, houses and cars release pollution into the atmosphere, it contains chemicals known as sulfur dioxide and nitrogen oxides. Sometimes, these chemicals fall directly back to the ground. This is called dry deposition. The rest of the time, they mix with water (moisture) in the air to form acids. Once these acids have formed, they can be transported long distances by the wind before being deposited in rain, snow or hail. This is what we commonly call acid rain.

During the 1970s, scientists in Sweden and Norway began noticing that acid rain was damaging their trees and fresh water. Much of the acid rain was caused by pollution that was transported through the air from other countries, primarily the United Kingdom. After that, acid rain was understood to be an international problem.

Acid rain can have harmful impacts on the ecosystems in the environment. It acidifies the soil and water where it falls, damaging or killing plants and animals. Surface water acidification can lead to a decline in, and loss of, fish populations and other aquatic species including frogs, snails and crayfish. Acid rain affects trees, usually by weakening them through damage to their leaves. Certain types of building stone, such as limestone and marble, can be slowly dissolved in acid rain.

Last modified February 4, 2008 by Becca Hatheway.

Shop Windows to the Universe Science Store!

Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Biomes and Ecosystems

Biomes are large regions of the world with similar plants, animals, and other living things that are adapted to the climate and other conditions. Explore the links below to learn more about different biomes....more

Air Pollution

What do smog, acid rain, carbon monoxide, fossil fuel exhausts, and tropospheric ozone have in common? They are all examples of air pollution. Air pollution is not new. As far back as the 13 th century,...more

Nitric Acid - HNO3

Nitric acid is a very strong acid that can burn your skin. Nitric acid has nitrogen, oxygen, and hydrogen atoms in it. There is a very tiny bit of nitric acid gas in Earth's atmosphere. Nitric acid is...more

Sulfuric Acid - H2SO4

Sulfuric acid is a very common type of acid. Acid rain has sulfuric acid in it. Acid rain harms plants, fish, and other living things. A type of air pollution causes acid rain. When people burn fossil...more

Rain

Rain is precipitation that falls to the Earth in drops of 5mm or more in diameter according to the US National Weather Service. Virga is rain that evaporates before reaching the ground. Raindrops form...more

Atmospheric Chemistry of Earth's Troposphere

When you think of chemistry, do you think about mixing colored liquids in test tubes and maybe making an explosion... or at least a nice puff of smoke? Did you know that a lot of chemistry happens in Earth's...more

Ammonia - NH3

Ammonia is a kind of gas. Ammonia molecules (NH3) have hydrogen and nitrogen atoms in them. The air you breathe has a tiny bit of ammonia in it. When plants and animals die and decay, they give off ammonia....more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF