Washington Post: As she did for winter 2010, this summer Mother Nature has truly outdone herself, this time by brewing up a miserable combination of heat and humidity that has enveloped not only the northeastern U.S., but much of the Northern Hemisphere as well. As Ian Livingston reported on Saturday, July was the warmest single calendar month of all time in Washington (tied with July 1993). The warmest day in the city was July 7th, when the temperature soared to 102 degrees Fahrenheit at Reagan National …