Climate Central: Global warming often conjures scenes of sweaty, scorching summer days, but daytime temperatures arent the only thing expected to rise in a warming world. Nights, too, are expected to get sultrier, with overnight lows not dropping as much as they used to. That trend in increasing nighttime low temperatures is expected to continue for the entire U.S. as greenhouse gas emissions continue to rise and trap more and more heat. This trend has important human health implications and could affect power...