Scientific American: No wonder its gonna be a hot time in the old town tonight. Cities can be anywhere from 2 to 20 degrees Fahrenheit hotter than nearby countryside, due to whats known as the "urban heat island" effect. But when heat waves roll through, they interact synergistically with the urban heat islandboosting temperatures even higher than you might expect. Researchers used a June 2008 heat wave in Baltimore as a case study. They compared temperatures downtown to those near the Baltimore/Washington International...