This morning I noticed a large, fairly low-flying, 4- engined passenger
jet go overhead through a clear blue sky (it appeared to be still in
takeoff mode from Stansted).

What immediately struck me was that it was creating a large sheet of
condensation (?) in its wake, the sheet forming a delta shape, with the
apex somewhere just under the body of the aircraft. The condensate only
lasted a few seconds before it evaporated, but the continuous production
of it looked as if the plane was trailing a large white sheet behind it.

I've seen planes form short-lived vortices of condensation from the
wingtips, but never anything as extensive as this.

It looked quite spectacular as it went overhead. I assume that pressure
differences over the wings was reducing the temperature in air that was
close to saturation(?)

- Tom
Blackmore, Essex.