Beginning of Essay
forms when sulfur and nitrogen dioxides combine with moisture in the atmosphere to produce rain, snow, or another kind of precipitation. This kind of pollution may also be suspended in fog or deposited in a dry form. Acid rain is most common in North America an ....

Middle of Essay
.... changed in to gases and others become tiny specks of ash. As these chemicals drift, they may change again. They may react with other chemicals in the air. When sulfur dioxide combines with water, the result is sulfuric acid. When nitrogen oxide gas combines with water, the result is also another acid. When the clouds releases rain or other precipitation, the acid goes with it. This is called acid rain. The level of acid is measured in pH levels. The pH scale begins at 0 and ends with 14. A reading lower than 7 is called acidic, and a reading higher than 7 is called basic. Seven is neutral. Normal rain is slightly acidic with a pH level of abo ....