You searched for: “acid rains
acid rain (s) (noun), acid rains (pl)
Rain, or other precipitation that has an excessive concentration of sulfuric or nitric acids; acidic rain; acidic precipitation: Acid rain is a popular term for the atmospheric deposition of acidified rain, snow, sleet, hail, acidifying gases and particles, as well as acidified fog and cloud water.

Any kind of precipitation or fog water having a pH less than 5.65 is termed to be acid rain.

Acid rain is the deposition of acidifying substances from the atmosphere during an event of precipitation.