It's getting dimmer out here...

We've all heard plenty about global warming. In fact, the discussion of its effects has been so overused in popular culture that it is not unusual to hear the term flippantly tossed about in casual conversation. Unseasonably warm? "We sure have to love global warming!" Ridiculously cold? "Where is this global warming everyone's been threatening?"

Well, according to some scientists, including Dr. David Travis at UW-Whitewater, that global warming we've all been threatened with could be here already - even more so than we could have imagined. One possible reason that we might not be feeling the effects yet of the advanced damage done to our environment is an effect called global dimming. And, a major factor for that dimming is the contrails from airplanes that litter America's skies. (Make sure you run your mouse over the top image on the previous link.)

Tuesday night's Nova, "Dimming the Sun," explores the effects of global dimming while discussing the possibilities for its reversal with experts like Travis and other scientists from around the world. The program, which airs at 7 on WPT, interestingly explores the rare opportunity presented by the grounding of domestic air flight in the days after Sept. 11, 2001 for scientists to experiment with the lack of aircraft contrails and the striking findings that occurred.