Acid rain
From Tardis Wiki, the free Doctor Who reference
Acid rain was unnaturally acidic rain.
Skaro, and especially Kaalann, had become so polluted that it constantly rained acid. (GAME: City of the Daleks)
Marran Alpha had constant acid rain. (AUDIO: The Dark Flame)
In 5345, the harvest rangers used satellites to produce acid rain to melt down Androzani trees for fuel. (TV: The Doctor, the Widow and the Wardrobe)
