What is acid rain?
Answer. When rain or snow falls it captures environmental pollutants from factory, automobile and truck exhaust. The sun heats and evaporates the water but leaves behind concentrated acid spots which cannot be removed. Prevention is the key here. Keep a good coat of wax on the finish and wash your car, especially after a rain or snowstorm.
Acid Rain is caused when sulfur dioxide (SO2) and nitrogen oxides (NOx) — pollutants released from burning coal, oil, and other fossil fuels — chemically react with other substances in the atmosphere to form acidic compounds. When these acidic compounds are carried down from the atmosphere in rain, fog, snow or dust, they can end up in lakes and streams, on buildings and monuments or on trees and land. They can harm fish, damage high-altitude forests and can deteriorate buildings and historical monuments. The pollutants that cause acid rain also have been known to worsen asthma and other lung ailments and to impair visibility in many regions of the nation including scenic vistas of our national parks.
Acid rain is more acidic than normal rain and forms through a complex process of chemical reactions involving air pollution. The two most important pollutants that contribute to the formation of acid rain are oxides of nitrogen and sulfur dioxide, which react with moisture in the atmosphere to form nitric and sulfuric acid. The sulfur and nitrogen compounds that contribute to acid rain primarily come from manmade sources, such as industries and utilities. Emissions also come from automobiles and other forms of transportation and industrial processes, such as smelting. Acid rain can harm forests and crops, damage bodies of water, and contribute to the damage of statues and buildings. Researchers are considering the possible effects of acid rain on human heath. These acidic pollutants can be deposited through rain, snow, fog, dew, or sleet. Large quantities can also be deposited in a dry form through dust. Pollutants that contribute to acid rain may be carried hundreds of miles before be
The term “acid rain” is commonly used to mean the deposition of acidic components in rain, snow, fog, dew, or dry particles. The more accurate term is “acid precipitation.” Distilled water, which contains no carbon dioxide, has a neutral pH of 7. Liquids with a pH less than 7 are acid, and those with a pH greater than 7 are alkaline (or basic). “Clean” or unpolluted rain has a slightly acidic pH of 5.6, because carbon dioxide and water in the air react together to form carbonic acid, a weak acid. Around Washington, D.C., however, the average rain pH is between 4.2 and 4.4. The extra acidity in rain comes from the reaction of air pollutants, primarily sulfur oxides and nitrogen oxides, with water in the air to form strong acids (like sulfuric and nitric acid). The main sources of these pollutants are vehicles and industrial and power-generating plants. In Washington, the main local sources are cars, trucks, and buses.
Rain cloudsAcid rain is rain that has been made acidic by certain pollutants in the air. 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 wet and dry forms falls on buildings, cars, and trees and can make lakes acidic. Acid deposition in dry form can be inhaled by people and can cause health problems in some people. What is acidity? Acidic and basic are two ways that we describe chemical compounds. Acidity is measured using a pH scale. A pH scale runs from zero (the most acidic) to 14 (the most basic or alkaline). A substance that is neither basic or acidic is called “neutral”, and this has a pH of 7. More about the pH scale and how pH is measured.
