Rain water with a pH less than 5.6 is called Acid rain. Normal, clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic. When sulphur dioxide and nitrogen oxides are released into the air, they react with water and oxygen and produces sulphuric and nitric acids. Thus it forms acid rain.
Effects of Acid rain
- Wherever acid rain falls it can have a serious effect on soil, trees, buildings and water.
- It is very dangerous as it causes serious damages to the living organisms as well as non-living things.
- Acid rain runs off the land and ends up in streams, lakes and marshes.
- The worst affected are things made from limestone or sandstone as these types of rock are particularly susceptible and can be affected by air pollution in gaseous form as well as by acid rain.