Acid Rain | Acid Rain Definition | How is acid rain formed?

Acid Rain Definition:

Acid rain is any form of precipitation that is unusually acidic (elevated level of hydrogen ions) due to anthropogenic gaseous emissions in the atmosphere. Acid rain contains acidic components such as sulfuric acid and nitric acid.

Brief History of Acid Rain:

The term acid rain was coined by Robert Angus Smith (Scottish pharmacist) in Manchester, England in 1872. He noticed a high level of acidifying rain falling over the industrial area of England as compared to less polluted areas near the coast. Little attention was given to his work until the 1950s when biologists observed the decline of fish population in the lakes of southern Norway and finally traced the problem of acid rain. Similar findings were also noticed in the 1960s in North America. These findings spurred intense research to understand the origin of the acid rain phenomena.

Measuring Acid Rain: (How it can be determined if rain is acid rain)

Acid rain is measured on a pH scale. Acid rain is one of the most serious environmental problems that emerged due to air pollution. Normal or unpolluted rainfall has a pH of 5.6 because carbon dioxide and water in the air react together to form carbonic acid, a weak acid.

CO2 + H2O............   H2CO3 (carbonic acid).

The term acid rain is applied to any type of precipitation with a pH level below 5.

Acid Rain Formation: 

Acid rain is the consequence of air pollution. When moisture of air reacts with oxides of carbon, sulfur, and nitrogen in the atmosphere to produce a mixture of carbonic, sulfuric, and nitric acids.

                   

  

Causes and Sources of Acid Rain:

• Anthropogenic activities are the main cause of acid rain which includes the burning of fossil fuel.
• The emission of gases from automobiles.
• Burning of coal from Power plant 
• The emission of gases from industries
• Both Sulfur dioxide and Nitrogen dioxide are the major sources of acid rain formation.

Dry and Wet Deposition:

Wet deposition refers to fog,  acid rain, and snow. Wet deposition of acid rain affects a variety of plants and animals. Dry deposition refers to acidic gases and particles. Almost half of the acidity in the atmosphere falls back to the ground through dry deposition.