Acid rain is primarily caused by the release of sulfur dioxide (SO2) and nitrogen oxides (NOx) into the atmosphere. These gases react with water, oxygen, and other substances to form sulfuric acid (H2SO4) and nitric acid (HNO3). These acids then fall to the ground in the form of rain, snow, fog, or dry particles.

Here's a breakdown:

* Sulfur Dioxide (SO2): This gas is released primarily from the burning of fossil fuels like coal and oil, as well as industrial processes.

* Nitrogen Oxides (NOx): These gases are formed during combustion processes, especially in vehicle engines and power plants.

It's important to note that while SO2 and NOx are the primary contributors to acid rain, other pollutants like ammonia (NH3) and volatile organic compounds (VOCs) can also contribute to the formation of acid rain.