What exactly causes that brown smog that lingers over large cities on sunny days? We know that thousands of chemicals act as a warming blanket, absorbing sunlight and trapping surface heat. However, the precise chemistry is not well known. Recently, PNNL scientists examined the chemistry of brown carbon, a pernicious set of particles in the haze. They focused on the specks that form around toluene, a common chemical pollutant. They found that nitrogen oxide, a product of car exhaust, resulted in particles that trapped heat. Increasing the nitrogen oxide level, however, resulted in particles that held significantly more heat and caused the mix to turn that familiar yellowish brown. Read more about this research at http://goo.gl/SWsMVT.
Franklin failed at his 13th virtue, Humility. Why? Was the most difficult virtue on this list the last? Or was there another reason? The answer is obvious and simple. Franklin had not failed at his virtues. He had succeeded at each of his twelve virtues. He failed at a virtue that was not his, a virtue that had been given to him by someone else. Franklin failed at a virtue that he did not value. He failed at doing something someone else valued and suggested to him as a value.