One example of ironic contrast is someone saying, "It's certainly lovely out today," when the weather is in fact terrible. The contrast between the description and the facts is an instance of verbal irony. In broad terms, irony refers to the incongruity between what is expected and what actually happens.
There are many other kinds of irony such as dramatic, cosmic, Socratic, situational, romantic and dramatic. A famous example of situational irony is when John Hinckley attempted to assassinate President Ronald Reagan. All of Hinckley's shots missed the president, but one bullet ricocheted off of the bullet-proof presidential limousine and struck Reagan.