Most of us first spot them as children—the white lines in the blue sky that are the telltale sign of a flight overhead. Contrails are an instant visual reminder of air travel, and a source of much controversy in recent decades. Put aside the overblown conspiracies, though, and there are some genuine scientific concerns to explore.
See, those white streaks planes leave in the sky aren’t just eye-catching. It seems they may also be having a notable impact on our climate. Recent research shows their warming effect is comparable to the impact of aviation’s CO2 emissions. The question is then simple—how do we stop these icy lines from heating our precious Earth?
But How?
A Qantas airliner releases contrails at 36,000 feet. Note the contrails form some way behind the outlet of the engines—the water vapor in the hot exhaust takes time to cool and form ice crystals around tiny particles that act as nucleation points. Sergey Kustov, CC BY-SA 3.0
The name contrails is a portmanteau of “condensation trails,” which tells you everything you need to know. Those white streaks form when aircraft fly through cold, humid areas of the atmosphere. They come about when water vapor mixes with tiny particles of soot and sulfur in the aircraft’s exhaust, which act as nucleation points for forming water droplets. These then tend to freeze in low temperature conditions, creating icy particles behind the aircraft. The r ..
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