acid precipitation acid precipitation /ˈæsɪd ˌprɛsɪpɪˈteɪʃən/

noun

1. Rain containing acids that form in the atmosphere when industrial gas emissions (especially sulfur dioxide and nitrogen oxides) combine with water  ( acid precipitation , acid rain )
   rain containing acids that form in the atmosphere when industrial gas emissions (especially sulfur dioxide and nitrogen oxides) combine with water