Acid rain is defined as any form of precipitation—including rain, snow, and fog—that has a pH lower than the natural acidity level, primarily due to the atmospheric deposition of acidic pollutants. This condition arises when atmospheric gases, predominantly sulfur dioxide and nitrogen oxides, react with water and oxygen. These chemical reactions form strong acids, such as sulfuric and nitric acid, which are then deposited onto terrestrial and aquatic ecosystems. The resulting acidification can drastically alter environments by leaching essential nutrients from soil, harming vegetation, and lowering the pH of surface waters. Such changes negatively impact aquatic life, as many species are sensitive to fluctuations in water acidity, and can also cause deterioration of materials like stone and metal structures.