What is acid rain?
Acid rain is rain consisting of water droplets that are unusually acidic because of atmospheric pollution - most notably the excessive amounts of sulfur and nitrogen released by cars and industrial processes.
Acid rain is rain, snow, sleet, or hail containing high levels of sulfuric or nitric acids with a pH below 5.5-5.6.
Acid rain is also called acid deposition because this term includes other forms of acidic precipitation such as snow.
History of acid rain
Acid rain has been an increasingly serious problem since the 1950s, particularly in Northeastern United States, Canada, and western Europe, especially Scandinavia.
It began entering the atmosphere in large amounts during the Industrial Revolution and was first discovered by a Scottish chemist, Robert Angus Smith, in 1852. In that year, he discovered the relationship between acid rain and atmospheric pollution in Manchester, England.Although it was discovered in the 1800s, acid deposition did not gain significant public attention until the 1960s and the term acid rain was coined in 1972. Public attention further increased in the 1970s.
Acidic deposition occurs in two ways: wet and dry.
Wet deposition is any form of precipitation that removes acids from the atmosphere and deposits them on the Earth’s surface.
Dry deposition polluting particles and gases stick to the ground via dust and smoke in the absence of precipitation. This form of deposition is dangerous however because precipitation can eventually wash pollutants into streams, lakes, and rivers.
Acidity itself is determined based on the pH level of the water droplets. PH is the scale measuring the amount of acid in the water and liquid. The pH scale ranges from 0 to 14 with lower pH being more acidic while a high pH is alkaline; seven is neutral. Normal rain water is slightly acidic and has a pH range of 5.3-6.0. Acid deposition is anything below that scale.
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