 The most widely recognized forms of implicature use figures of speech (tropes). Irony, overstatement (hyperbole), understatement (meiosis and litotes), and metaphor have been known at least since Aristotle. They are taught in school as elements of style. When Don said in  (2) The weather is lovely, he used irony and implicated that the weather is awful. Don did so in part to make light of the awful weather. Don could have implicated the same thing by saying The weather is not good (litotes) or The weather is the worst in history (hyperbole).