"Martin Rowley" schreef in
bericht ...

"Tom Bennett" wrote in message
...
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.

... see the FAQ Q/A 2A.11

I've actually seen military aircraft with full fuel load (having
difficulty lifting clear by the end of the runway) just after dawn
(high
RH ... 96%), actually feeding into a pre-existing sheet of shallow
fog
(MIFG) and temporarily thickening same to 'proper' fog (BCFG), though
by
the same token, the wake of the a/c then causes turbulence which mixes
down unsaturated air from just above the fog layer and the entire
sheet
disappears!

Martin.


--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm



In the old days, 1946 etc., DC3's starting their flight from Medan,
Sumatra, to Batavia -now Jakarta- Java, in the early morning when RH
was high, produced condensation rings behind the propellors. Visible
only for a short distance. Trying to visualize the picture, I think that
the extent was not more than the diameter of the propellor circle.
Good old days ;-(

Sytze Stel