If you've ever looked up at the sky and seen an airliner flying overhead, you may have noticed white trails behind it.

Last weekend, when the weather was clear and near 90 degrees and so many of us were outside trying to soak up as much sunshine as we could, a lot of people noticed that jet trails (contrails) were ...

All commercial aircraft across the United States and Canada were grounded for three days following the terrorist attacks of September 11, 2001. That constituted a gigantic unplanned weather experiment ...