The pros and contrails of travelling by air

ANOTHER LIFE:THE FIRST CLEAR dawn in weeks offered most of a moon in the seaward sky and a peachy glow of sunrise behind the mountain. Out on my morning march, I lifted my eyes to an early augury of winter. Two bright contrails of transatlantic flights were converging from the ocean, each led over Mweelrea's summit by a glinting pinpoint of light. I watched as the high wind snatched at the tails of the ice plumes, whisking them away in dissipating wisps.

Strange marks on the sky have fascinated people since the Stone Age. They still worry some people of apprehensive disposition (at whose concerns I shall arrive). But vapour trails’ role in making clouds is now part of the study of global warming, and the crowded sky over Ireland is a target for satellite surveillance.

Clouds trap the sun’s warmth reflected from the planet. They are made by the condensation of moist air into droplets of water or ice, each with an airborne particle or aerosol at its heart. Earth sends all kinds of natural particles and aerosol molecules into the atmosphere, to which aircraft add millions of their own.

The jet exhaust from burned kerosene pours out warm and moist gases, with sulphates, carbon soot and metal molecules, all of which condense into a linear ice cloud in the colder ambient air. In favourable conditions – typically below minus 40 degrees – a contrail can persist for several hours, grow to several kilometres long and trigger additional cirrus cloud as it spreads.

Ireland’s position under the north Atlantic flight corridor means that hundreds of aircraft to and from Europe fly over the island daily at more than 24,000ft, peaking eastwards in the early morning and westwards around noon. An Armagh Observatory study of Irish sunshine records over the century to 1998 found a 15 per cent increase in cloud cover and a corresponding 20 per cent drop in annual sunshine. How much of this, if any, could be blamed on the modern rise in air traffic?

To help study the effect of contrails on Ireland’s skies, a team led by Dr Gillian Whelan of the geography department at University College Cork, with atmospheric scientists from Germany and Nasa, has devised an automated system of sorting contrails from natural cirrus cloud by satellite thermal imaging. Tracking them through 2008, the team found contrails thickest on winter nights, with a peak at 4 am. Some were exceptionally thick when compared with other studies over Europe.

Such findings, as surveillance continues, may strengthen arguments for flying at lower altitudes or changing routes to avoid sensitive masses of humid air. (But what happens to the emissions?) Contrails seen as threatening “chemtrails” have been with us as long as UFOs, and with much the same origins in widespread American social paranoia: my first alerting missive arrived from Florida almost three decades ago. People prone to believing governments are doing secret things to the world are given to watching the sky for sinister shapes in the clouds. Their suspicions are nurtured by websites, blogs and videos offering “evidence” for state or corporate conspiracy.

Early anxieties fed on rumours of cancer-causing chemicals or pathogens sifting down from contrails over American cities. More recently, the favoured “poison” has been barium, a metal element quite normally present in rainwater but inaccurately reported in improbable concentrations on YouTube. In one Irish blog, persistent “chemtrails” are blamed for poor summers, “to make people use more gas and electricity”.

My latest e-mail on the subject comes from a teacher in Co Kildare, with “an MSc and BSc in applied physics”. He is convinced that the persistent contrails he sees are, indeed, “chemtrails”, intended to control climate change through geoengineering, probably at the instigation of the UN. The contrails he used to see 10 years ago dissipated quickly, he points out, whereas “in 2011 they are all of a sudden forming cirrus clouds”. There are days “when they literally criss-cross the sky”, so their constituents must have changed. With what, he demands to know, are we being sprayed?

Just now, such concerns are intensified by projects that might, indeed, change the sky. The latest, in Britain, is Stratospheric Particle Injection for Climate Engineering, or Spice, a collaboration between researchers at the universities of Bristol, Edinburgh, Oxford and Cambridge, together with Marshall Aerospace. It proposes raising a pipe to the stratosphere, held up by a helium balloon. Through it could be pumped a flow of suitable particles, yet to be selected, to reflect back into space a helpful few per cent of incoming solar radiation.

The first kilometre of pipe could soon rear up, cobra-like, to be filled with water as a preliminary feasibility test. “Mature and wide-ranging debate”, the project’s leaders agree, should explore the potential consequences. The company of internet theorists will be ready to play their part.

Eye on nature

I found a cluster of yellow caviar-like eggs interwoven with whitish, sticky strings of slime. First I thought the cat had thrown it up; it looked exactly like scrambled egg. Could it have been left by a snail or slug?

Justin Doyle, Virginia, Co Cavan

It was the scrambled egg slime mould,Fulgia septica in the spore-producing form. Slime moulds are masses of protoplasm that can move and feed on bacteria, spores of fungi, plants and particles of organic matter.

In late September I looked up to see a vociferously protesting raven being escorted from the parish by a dozen swallows.

David Hough, Newtowncunningham, Co Donegal

Above Coumshingaun in the Comeraghs we saw and heard a bird that looked like a large crow standing proud on a rock. The sound it made was not “caw, caw” but “boing, boing”.

Leigh Timpson, Cork

It sounds like a chough.

Sunday 16th October: beautiful sight; beautiful day; two dolphins cavorting in Killiney Bay.

Paul Byrne, Cabinteely, Co Dublin

When leaving the office today, a little creature about the size of a pen top was quietly hanging around. Is it a newt, lizard or salamander?

Fiona Doran, Strandhill, Co Sligo

From your photograph, it is a lizard.

Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo, or e-mail viney@anu.ie. Please include a postal address.