I know i'm a bit on the suspicious side but...

[Saintaw]

Originally posted by WhiteHawk
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I still cant figure out how to post pics.  Here thoguh.  No biggie.

http://www.picturehangar.com has registrations closed except for AH members, drop an email to tbolt at onpoi dot net with your BBS handle, and you'll have an account.

Oh, and fess up, you just wanted to use this:

[Phaser11]

KC-10 Tanker.
 Has 3 engines (note 3 contrails). Bottom of aircraft are white (some are night fighter gray). Not many of them left, but there still in use. Krazy big GE turbo Fans on these aircraft. When thay area not to heavy with fuel or cargo, they can scoot.

[Furball]

dont airliners have a waste gas exhaust at the back of the tail?

would explain how the twin is making 3 contrails.

[Golfer]

dont airliners have a waste gas exhaust at the back of the tail?

would explain how the twin is making 3 contrails.

If you're thinking of the unfinished exhaust at the back of an airplane (I think you are) that's the APU exhaust.  Aux. Power Unit which is what runs when airliners are parked on the ground to keep air conditioning, electrical and hydraulic systems running.  They also run in flight but are limited from model to model at which altitude it can start and run.  You don't typically use these in flight unless you're transferring the bleed air systems and pressurization to it on an approach to use all available engine thrust for a missed approach or go-around.  It's basically just a small turbine engine mounted in the airplane.

If you're thinking of an outflow valve for a pressurization system on an airplane that won't do it either.  For one, the temperature isn't high enough.

If you're thinking of a lav vent tube...quite possible given some of the people I've seen use the Lavs on airliners nowadays

[Edbert]

DC10 would have left the three trails too.

[Golfer]

I think it looks like 2 contrails that overlap rather than 3.

[cpxxx]

I'll try and address the original question and ignore the madness. I am by no means an expert, whitehawk. But basically the difference in contrails is due to differences in altitude flown by the aircraft and the fact that bigger turbofan engines produce bigger trails.

Thus a 737 at the same altitude as an MD-11 will produce less vapour.  Also contrails can only exist in a certain temperature range. That's why they suddenly appeared. The aircraft had probably climbed into the right temperature range. The trail also varies according to the temperature. An aircraft flying in the optimum temperature will produce a much bigger trail than one a couple of thousand feet higher or lower.

That is the boringly prosaic explanation, I'm afraid.

[Furball]

Originally posted by cpxxx
I'll try and address the original question and ignore the madness. I am by no means an expert, whitehawk. But basically the difference in contrails is due to differences in altitude flown by the aircraft and the fact that bigger turbofan engines produce bigger trails.

Thus a 737 at the same altitude as an MD-11 will produce less vapour.  Also contrails can only exist in a certain temperature range. That's why they suddenly appeared. The aircraft had probably climbed into the right temperature range. The trail also varies according to the temperature. An aircraft flying in the optimum temperature will produce a much bigger trail than one a couple of thousand feet higher or lower.

That is the boringly prosaic explanation, I'm afraid.

YOU NUTBAR!

it is quite clearly cloudseeding! now go see a shrink!