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
Lower sulfur oxides has been detected in the gas phase using neutralization-reionization mass spectrometry. Both cyclic and chain structures were found. A number of monoxides SO are known where n= 5-10, where the oxygen is bonded to one sulfur. They can be prepared by oxidising the homocycles with trifluoroperoxoacetic acid: The compounds are yellow or orange-coloured and thermally unstable near room temperature. One dioxide is well characterized: the deep orange SO (m.p. 60–62 °�C with decomposition), which arises using trifluoroperoxoacetic acid. Lower sulfur oxides The lower sulfur oxides are a group of inorganic compounds with the formula SO, where m < 2n. These