CBS News, Aired July 29, 2006 2:19 PM. Contrails are lines of exhaust left by planes. It can be fun to watch them as they crisscross the sky. But as Anthony Mason reports, some people think they could spell trouble for the planet. 
New research suggests that jet exhaust is four times better at trapping heat than ground emissions with contrails playing a critical role. Contrails form at high altitudes when hot jet engines pass through cold moist air. The clouds spread out trapping heat rising from the surface.
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