In response to JS Moore’s letter (Your Say, December 11) concerning the aircraft condensation trails which were shown in my photograph (Viewfinder, November 27), I can assure her that the trails are not toxic in any way.

Condensation trails (not “fumes”) are composed of ice crystals and are always at a very high altitude, usually above 30,000ft. Jet fuel contains a tiny percentage of water (as do most other types of fuel) and this comes out in the engine exhaust.

The water vapour is not normally visible but if the air is cold enough, as it is at high altitude, this water vapour immediately freezes causing a visible condensation trail to form.

Broadly speaking, a condensation trail is a very thin and very narrow cirrus cloud.

I wanted my photograph to highlight our thanks to air traffic controllers for keeping our south-east sky safe.

H FONEY
by email

 



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