10/22/2004: Contrails over southern US

[tw]

Originally Posted by capnhowdy

I don't know Jack about contrails, but my observation is this: Evidently they are controlled by altitude and/or weather conditions.

Always look for the unusual outside an airplane window. In certain conditions, air spinning off the end of a wing creates a cloud - a long cloud. (Same applies to engine exhaust.) Never read a good reason why this happens. But those little winglets now on the newer planes is all about keeping that air from spinning off the wing - same air that can sometimes result in a long thin cloud behind a plane.