Acid Deposition (Acid Rain) 1 : Water that falls to or condenses on the Earth's surface as rain, drizzle, snow, sleet, hail, dew, frost, or fog with a pH of less than 5.6
EESiFlo North America, Terminology and Glossary: Water Terminology, Pennsylvania, USA 2002. flowmeterdirectory.com/flowmeter_terminology, (Wtr - Amer) {580}