How is acid rain formed
There are three main causes of acid rain, but both are due to the same gases being released into the atmosphere. Acid rain is caused by the two main air pollutants, sulfur dioxide and nitrogen oxide. When these gases come into contact with the hydrogen and oxygen molecules in water they combine to form a weak acid. The major cause of acid rain is air pollution by burning fossil fuels, smelting metals and motor vehicles. Acid rain can also be caused naturally by the eruption of a volcano. When a volcano erupts it produces a large amount of sulfur dioxide and it is not uncommon to have acid rain. Acid rain can also be caused by lightning strikes as these naturally produce nitrogen oxide.