It was learned that contrails lower daytime and raise nighttime temperatures slightly in high-traffic jet corridors. Lacking those clouds for a few days after Sept. 11, the spread between daily high and low temperatures increased by about 2 degrees Fahrenheit.
There has been controversy over the global impact that jets have on the Earth’s atmosphere. Some of the comments in Upgrade: Travel Better’s post on the subject questioned if 3 days of data could really be conclusive. Those of you who’ve calculated the carbon impact of a recent vacation will find that air travel is where most of your carbon tonnage comes from.