Acid Rain: occurs when the pH of precipitation is lowered below a pH of 5

Air Pollution: considered to be any substance released into the atmosphere in harmful amounts

Condensation Nuclei: pieces of dust, dirt, ash, etc. around which ice and water droplets collect

Conduction: transfers heat through direct contact between two objects

Convection: transfers heat through the movement of fluids or gases in circulation cells

Convection Current: the circulating path of hot water heating & rising and cold water cooling & sinking

Particulate Matter: includes liquid droplets and solid materials suspended in the air

Photochemical Smog: haze created mainly from automobile exhaust interacting with sunlight

Radiation: transfers energy by electromagnetic waves

Temperature Inversion: an increase in atmospheric temperature with altitude