When sulfur dioxide reacts with water droplets in the air, it forms a substance that falls back to Earth as sulfurous acid. The equation that rules the transformation is: SO2 + H2O ---> H2SO3
Sulfurous acid can undergoes further transformation and form sulfuric acid which is what cause the acid rain.
Answer: The illusion of motion that occurs when a stationary object is first seen briefly in one location and, following a short interval, is seen in another location.
