Contrails' Impact Worse At Night?

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It's been a while since we heard from the chemtrail crowd -- the foil-hatted bunch who believe jet contrails are really the deployment of mind-control chemicals -- but news coming out of a UK-based university may have them howling at the moon again. The reason is a new study that concludes -- get this -- that nighttime jet operations may have a greater impact on the world climate than those formed during daylight hours. The study -- conducted by the Meteorology Department at Great Britain's University of Reading and published this week in Nature -- suggests that a widespread adoption of night-flying restrictions could help minimize the impact. The study shows that even though only one in four flights over the UK occur during the night, these flights are responsible for at least 60% of the climate warming associated with aircraft condensation trails (contrails).

According to the university, contrails affect the climate by reflecting some of the sunís energy back to space, which cools the earth. At the same time, they enhance the natural greenhouse effect by trapping energy emitted from the Earthís surface in the atmosphere, leading to warming. On average the greenhouse effect prevails and the climate warms. The contribution that nighttime flying makes to climate warming is so high because the cooling effect only happens when the sun is up, whereas the warming effect occurs both day and night. The study concentrated on "persistent contrails" -- those remaining for an hour or so after forming. Said one researcher involved in the study, "The findings have implications beyond their pure scientific value; they could be used if policy makers decided to modify flight management systems in order to reduce the climate impact of aviation."