1. Sulfur dioxide (SO2): This gas is primarily released from burning fossil fuels, especially coal. It reacts with water, oxygen, and other substances in the atmosphere to form sulfuric acid.

2. Nitrogen oxides (NOx): These gases are also released from burning fossil fuels, as well as from vehicle exhaust. They react with water, oxygen, and other substances to form nitric acid.

3. Carbon dioxide (CO2): While primarily known for its role in climate change, CO2 also contributes to acid rain. It dissolves in water to form carbonic acid, which is a weak acid.

It's important to note that while CO2 contributes to acid rain, its impact is much smaller compared to sulfur dioxide and nitrogen oxides.