"an acerbic tone piercing otherwise flowery prose"
"a barrage of acid comments"
"her acrid remarks make her many enemies"
"bitter words"
"blistering criticism"
"caustic jokes about political assassination, talk-show hosts and medical ethics"
"a sulfurous denunciation"
"a vitriolic critique"

"the summer was sultry and oppressive"
"the stifling atmosphere"
"the sulfurous atmosphere preceding a thunderstorm"