What Is Acid Rain?
Acid rain is created when rain mixes with pollution in the air. Pollution fills the air with an invisible gas called sulfur dioxide. (This gas is mainly a result of coal burning.) Sulfur dioxide combines with water in the air and sunlight to form a weak sulfuric acid that gives acid rain its bitter taste.
Acid rain can fall hundreds of miles from the nearest factory smokestacks. In cities, acid rain can cause damage and decay of buildings and statues. In rivers and lakes, it can kill fish, and on land, it can damage soil needed for the proper growth of plants.
Acid rain is a type of acid deposition, which can appear in many forms. Wet deposition is rain, sleet, snow, or fog that has become more acidic than normal. Dry deposition is another form of acid deposition, and this is when gases and dust particles become acidic.
Both wet and dry deposition can be carried by the wind, sometimes for very long distances. Acid deposition in dry form can be inhaled by people and can cause health problems in some people.
Human activities are the main cause of acid rain. Over the past few decades, humans have released so many different chemicals into the air that they have changed the mix of gases in the atmosphere.
Power plants release the majority of sulfur dioxide and much of the nitrogen oxides when they burn fossil fuels, such as coal, to produce electricity. In addition, the exhaust from cars, trucks, and buses releases nitrogen oxides and sulfur dioxide into the air. These pollutants cause acid rain.