What is acid rain?

Acid rain refers to any form of precipitation, such as rain, snow, sleet, fog, or dew, that contains higher-than-normal levels of acidic compounds like nitric acid and sulfuric acid. It is a significant environmental issue because of its harmful effects on plants, animals, water bodies, and even man-made structures. Acid rain can occur as either wet deposition (precipitation like rain, snow, fog, etc.) or dry deposition (acidic particles and gases that settle on surfaces without precipitation).

How is Acid Rain Formed?

Acid rain is primarily caused by the release of pollutants into the atmosphere from human activities. The two key pollutants responsible for acid rain are sulfur dioxide (SO₂) and nitrogen oxides (NOₓ), both of which are emitted by burning fossil fuels like coal, oil, and natural gas. These pollutants come from several sources:

• Power stations: Burning coal and oil in power stations releases large amounts of sulfur dioxide (SO₂) into the air.
• Vehicles: Motor vehicles that burn petrol and diesel release nitrogen oxides (NOₓ) into the atmosphere.
• Factories and industrial processes: Certain industries, such as metal smelting and oil refining, also release sulfur dioxide and nitrogen oxides.

Once in the atmosphere, these gases react with water vapour, oxygen, and other chemicals to form sulfuric acid (H₂SO₄) and nitric acid (HNO₃). These acidic compounds mix with cloud water, eventually falling to the Earth as acid rain during precipitation.

The cause of acid rain

Wet and Dry Deposition

• Wet deposition occurs when acid chemicals are dissolved in water and fall to the ground as rain, snow, fog, or mist. This type of deposition directly affects lakes, rivers, and soil, often leading to environmental damage.
• Dry deposition happens when acid gases and particles settle on surfaces like buildings, plants, or water bodies without moisture. These particles can later be washed off by rain, creating further acidification.

Acid rain causes many problems.