millions of americans searching for sweet and cool relief over the last few days as triple-digit temperatures scorched states from the central u.s. and southwest to the east coast. but what exactly is the cause of this spike in the mercury? well, it's a weather phenomenon known as the heat dome. you've probably heard that phrase this week. if you want to sound smart today, tell your friends a heat dome is caused by a huge area of high pressure that traps and compresses hot, humid air from the gulf of mexico. that's according to the national weather service, which estimates the current heat dome covered some 1 million square miles. that's how to sound smart, if you want to sound cool just invite them into the ac today. let's gather around the water cooler to discuss the do's and don'ts of interviewing a public official. on wednesday chicago mayor rahm emanuel sat down with the local