Acid Rain in Washington vs Pennsylvania
Country: United States
Date: April 2006
Why is the pH in acid rain lower in Washington DC
than it is in Lancaster, PA?
The pH of rain is not constant. It depends upon geography, local
conditions, time of day, and a long list of other variables. In
general, the rainfall in metropolitan areas tends to be more acidic
(lower pH) than more rural areas. But that is a generalization that
has many exceptions because gases that tend to form acid rain (SO2,
NO2, ...) can move many hundreds of miles before the acids formed
by the reaction with water vapor falls to Earth.
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Update: June 2012