Acid rain Acid rain Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals and infrastructure. Acid rain is caused by emissions of sulphur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids. Some governments have made efforts since the 1970s to reduce the release of sulphur dioxide and nitrogen oxide into the atmosphere with positive results. Nitrogen oxides can also be produced naturally by lightning strikes, and sulphur dioxide
Nitrogen dioxide This reaction is negligibly slow at low concentrations of NO characteristic of the ambient atmosphere, although it does proceed upon NO uptake to surfaces. Such surface reaction is thought to produce gaseous HNO (often written as HONO) in outdoor and indoor environments. Nitric acid decomposes slowly to nitrogen dioxide by the overall reaction: The nitrogen dioxide so formed confers the characteristic yellow color often exhibited by this acid. is used to generate anhydrous metal nitrates from the oxides: Alkyl and metal iodides give the corresponding nitrites: is introduced into the environment by natural causes, including entry from the stratosphere, bacterial