Acid Rain is a rain that comes from a big smoke or from air pollution. The main cause is from industries wastes, then it affects the water form acids. It could cause environmental harm, typically forests and lakes.
Usually the first one is the industrial waste affected the waters, and then the waters that affected by the wastes form a pollution clouds and then the acid water fall down, that is how acid rain happens.
It can cause environmental harm to the marine life, forests, and lakes, those are the most common impacts of Acid Rain.