The Contrail Effect
by Peter Tyson
Are vapor trails from aircraft influencing the climate, and if so, should we worry?
I've always wanted to hate contrails, the "condensation trails" streaming out from behind jets. They're man-made.
They force lines on nature, which knows no lines. They arise out of pollution, and they generate visual pollution—aircraft graffiti that can erase blue from the sky and light from the sun. All good reasons to despise these artificial clouds.
But I don't. I've always been drawn to them. When I see one above, I like to run my eye along its length until I find the plane, a tiny silver toy.
I like to wonder at the blank space between the plane and the start of the contrail—emptiness full of potential—and then to see the churning new cloud as it forms, a tumbling cascade.
When the roiling slows and the newborn cloud settles into a contrail proper, I admire its perfection: a straight white line sharply etched against the blue.
Even when numerous contrails made fat by the wind crisscross the sky, I don't mind.
Well, I might now. After a lifetime of enjoying contrails, it came as a surprise to me to learn recently that something so ephemeral may not be a harmless by-product of the jet age but may in fact impact the climate. (image left from atmospheric cartoons)
This is of particular concern in well-traveled air corridors, where contrails by the hundreds can spread into man-made cirrus clouds that can both block sunlight from reaching the Earth and trap radiated heat from escaping to space.
Whether contrails cause a net cooling or a net warming, even whether their effect is something to worry about, remains unclear.
But with air traffic expected to double or even triple by 2050, leading contrail researchers say the influence of these artificial clouds cannot be ignored.
(for more of this article, click here)