Science
Acid rain.
Definition
Acid rain is precipitation with a pH below 5.6, caused primarily by sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) released from burning fossil fuels reacting with water vapor in the atmosphere to form sulfuric and nitric acids. It damages ecosystems, buildings, and water sources.
Examples
Real-world.
- 1 Acid rain has damaged marble statues and limestone buildings across Europe, including the Parthenon
- 2 Lakes in the Adirondack Mountains became too acidic for fish due to acid rain in the 20th century
- 3 The U.S. Clean Air Act amendments of 1990 significantly reduced acid rain by capping SO₂ emissions from power plants
Key Fact
Normal rain pH ≈ 5.6 (due to dissolved CO₂); acid rain pH < 5.6, often around 4.2–4.4.