The Return of the Contrails


The first contrails: London: 12:10 p.m. GMT

The end of the ban on flying seems to be touch and go with most flights still cancelled until later this afternoon. But some are rhapsodizing about a world without planes and the joys of cloud watching and bird song.

The Poet Laureate has written a poem : "the sky is as clean as a white slate" and "Britain's birds sing in this spring." No one is missing those long trails that come from the airplanes: contrails.
Image from the Daily Mail
Contrails: condensation trails from airplanes, only started appearing before the second world war. They aren't really clouds because they are long and straight and angular.

Gavin Pretor-Pinney, who wrote the Cloudspotter's Guide, and is the founder of the Cloud Appreciation Society, discussed, or should that be disgusted, the contrails. He said that:

"Aesthetically, I don't see contrails as worthy of our appreciation as much as the natural clouds. It's the formless, chaotic beauty that clouds bring to our skies that make them something to appreciate. Contrails are orderly lines of progress ... but most of the time I see them as being in opposition to natural clouds."

However, they do serve a purpose. They are good for predicting changes in the weather. If the contrails hang around it usually means there is a change in the weather coming. In 24 hours there may be cloud or rain.

After September 11, 2001, the last time when flights were grounded for 3 days, it turned out that the weather was warmer without the contrails. The average daily temperature range in the U.S. rose during that time. Scientists matched the weather over those three days with similar weather in previous Septembers over that period, and found that the difference in daily high and nightly low temperatures in the absence of planes' contrails was more than 1C greater.


Image from the Cloud Appreciation Society: Cirro-stratus clouds

This is because the contrails lead to the development of high clouds, cirrostratus, and they absorb the heat in the air.

Oddly enough, it has been warmer in Britain over the past weekend. However, according to the Bureau of Meteorology, the heat could be cancelled out by the volcanic ash, which act as contrails, absorbs the heat and reduces the temperature.

Silver Lining by Carol Duffy

Five miles up the hush and shush of ash,
Yet the sky is as clean as a white slate -
I could write my childhood there.
Selfish to sit in this garden, listening to the past
(A gentleman bee wooing its flower, a lawnmower)
When the grounded planes mean ruined plans,
Holidays on hold, sore absences at weddings, funerals ... wingless commerce.
But Britain's birds sing in this spring
From Inverness to Liverpool, from Crieff to Cardiff,
Oxford, Londontown, Land's End to John O' Groats.
The music's silent summons,
That Shakespeare heard and Edward Thomas and, briefly, us.

Tags: Airlines | Air Pollution | Air Travel