What is acid rain?
“Acid rain” is a term used to describe the many ways in which acids fall from the sky. Rain, snow, fog, dry gases, and particles may contain acids. Sulfur dioxide and nitrogen oxides released by power plants, cars and trucks, and other sources cause acid rain. Acid rain harms plants, animals, fish, and building surfaces. It can also create smog in the air and hurt people’s lungs. Since the energy used to power modern life (electricity and burning fuels like gas and oil) is the main cause of acid rain, there are many things you can do to stop or reduce its effects. • Turn off lights, computers, and other appliances when you are not using them. • Only use electrical appliances when you need them. • Keep your home well insulated. • Carpool, use public transportation, or walk or bike when you can. • Use appliances that are energy efficient. • Buy vehicles that only give off low levels of nitrogen oxide. Look for electric- or gas- powered or alternative-fueled cars.
According to the Web site Weather Underground, Acid rain is any precipitation, rain or snow, which is more acidic than “normal” rain or snow. Acidity of substances is measured on the pH scale. Normal levels for rain and snow have a pH level of 5.5. Anything less than this is considered acidic. In 2000, the lowest pH recorded in the United States was 4.3! When sulfur dioxide and nitrogen dioxide are released into the air from cars or factories, they cause the air to become more acidic. These gases combine with the water vapor to form weak acids that become part of the precipitation.
Rain and snow that fell on the earth were acidic long before man began weaving his magic and mischief. Pure water with a pH of 7 is actually a laboratory product rather than a natural substance. Water is not called the universal solvent without reason. Normally it includes a wide variety of dissolved gases, salts and other substances. As a result, the pH of normal rainfall that has not been affected by man’s pollution is mildly acidic. As the rain forms and falls, it dissolves gases from the atmosphere. Normal amounts of carbon dioxide in the air insure that precipitation that reaches earth has a pH below 7. In fact, most rain water will have a pH closer to 5 than it will 7. Since carbon dioxide is produced as a by-product of respiration, its presence in the atmosphere is natural and quite expected. The mild acid it produces generally causes no harm.
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.
Acid rain is rain that is more acidic than usual. It is caused by air pollution and affects the water that we use everyday. How is acid Rain Formed? The toxins and pollutants given off by burning fossil fuels are the major contributing factor to our problem with acid rain. Factories burn coal and oil in order to heat, light our homes, and run our appliances. Cars burn other fossil fuels, but they too give off pollutants which cause acid rain. Here’s what happens… The smoke and fumes from the burning fossil fuels rises into the atmosphere and mixes with the moisture in the air. The combination of toxins and moisture in the atmosphere form acid rain. The main toxins are Sulfur dioxide and nitrogen oxides. Usually the moisture in the air form higher in the clouds where the Sulfur dioxides and sulfur oxides are. It is there that they react with water and oxygen and form acid and nitric acid. Sunlight increases the rate at witch these reactions occur.
