User:Milton Beychok/Sandbox

Terminology

The following definitions describe the technical terms that have a special meaning to the study or discussion of acid rain:

Acid rain: A broad term that includes both wet and dry deposition of material from the atmosphere which contain higher than normal amounts of acids (predominantly sulfuric acid and nitric acid)..

Wet deposition: A term that refers to acidic rain, snow, fog, or mist that falls onto the ground from the atmosphere.

Dry deposition: A term that refers to the acids that may become incorporated into the dust and other particulates in the atmosphere and fall onto the ground, buildings, homes, cars, and trees. Dry deposition is washed from these surfaces by rainstorms, causing an increase in the acidity of the runoff water.

Precipitation: A term that refers to either or both wet and dry deposition.

Acids: A term that refers to the acids found in acid rain. The atmosphere contains acid precursors (chemical forerunners) such as gaseous sulfur dioxide and nitrogen oxides that originate from natural sources as well as man-made (anthropogenic) sources. Those gases react with water and oxygen in the atmosphere to form mild (low concentration) solutions of sulfuric and nitric acids.

Acidity: The acidity of acid rain is measured using a scale called "pH". The lower is the pH of a substance, the higher is its acidity (i.e., the more acidic it is). The pH scale ranges from 0 (strongly acidic) to 14 (strongly alkaline or basic). Pure water has a pH of 7.0 which is considered to be "neutral", meaning that it is neither acidic or basic. However, normal rainfall is slightly acidic because carbon dioxide (CO₂) in the atmosphere dissolves in the rain to form carbonic acid (H₂CO₃) which is weakly acidic and results in the rainfall having a pH of about 5.6.