Posts: 146
Joined: Mon Jan 05, 2004 2:33 am

How Do Contrails Form?

Mon Jan 26, 2004 12:33 pm


I was wondering how are the contrails formed behind the jet engines and why does one not see them behind aircrafts that overfly India or for that matter the whole sub-continent ...... Thank you... Big thumbs up
Posts: 4138
Joined: Sat Jan 29, 2000 9:14 am

RE: How Do Contrails Form?

Mon Jan 26, 2004 12:40 pm

When very hot air hits very cold air, condensation forms. I think there has to be moisture in the air for it to form....someone will provide more details.

Posts: 5351
Joined: Tue Oct 21, 2003 1:38 am

RE: How Do Contrails Form?

Mon Jan 26, 2004 12:42 pm

When airliners spray chemicals behind them at the behest of the government to keep us all under their control!  Nuts

Sorry, had to get the first chem trail crack in there.
South Carolina - too small to be its own country, too big to be a mental asylum.
Posts: 11191
Joined: Tue Jun 15, 1999 11:29 am

RE: How Do Contrails Form?

Mon Jan 26, 2004 12:44 pm


Welcome to a.net!

The contrails question has come up before, so you might want to use the search function and look at the previous threads. Lots of good answers there...

ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
Posts: 4727
Joined: Tue Jan 06, 2004 4:49 pm

RE: How Do Contrails Form?

Mon Jan 26, 2004 12:48 pm

Actually, one user had it down pretty well. The contrails are formed by the extreme heat in the aircraft engines reacting with extremely cold air found at high altitudes. The thickness of the contrail itself, usually whether or not it stays place in the air for long or dissipates, depends on the moisture located in the air at the time. However, they are usually formed regardless, unless it is unusually dry air, because of the speed to which the temperature of the air is changed...most undoubtedly in microseconds. Any change in temp that has that vast of a range will produce thick moisture. Then, if the air is cold enough, the newly created moisture becomes tiny ice crystals, suspended in the upper layers of the atmosphere. These are the ones that never seem to go away and are usually very thick.

Hope this helps.  Big thumbs up
Crye me a river
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Joined: Wed Jul 11, 2001 7:41 am

RE: How Do Contrails Form?

Sat Jan 31, 2004 4:53 am

The combustion of hydrocarbons (like Jet-A or even ordinary car gasoline) produces significant amounts of water vapour which adds to the preexisting air humidity; If the conditions are right, this can make the air cross the condensation point.
Posts: 2556
Joined: Sat Dec 06, 2003 1:30 am

RE: How Do Contrails Form?

Sat Jan 31, 2004 4:57 am

Condensation forms when air cools to the dew point. The water vapor has to come from the fuel itself. Otherwise the amount of moisture in the air would have already formed clouds at that altitude and the heating of the air by the engines would make the clouds go away temporarily. However, if the aircraft creates the water vapor and disperses it behind, that is water that is over and above what the colder air at that altitude can handle... so it condenses into contrails (i.e. clouds).

(side note... do y'all think it's time to bump my "Cloud Dreaming" poem up to the top?)
Dave Mark - Intrinsic Algorithm - Reducing the world to mathematical equations!
Posts: 2556
Joined: Sat Dec 06, 2003 1:30 am

RE: How Do Contrails Form?

Sat Jan 31, 2004 4:59 am

(it's archived so I can't bump it... so here it is... just for the sake of saking...)

Cloud Dreaming
Nov. 13, 2003
© Dave Mark

When we were young
We all were told
To look up in the sky
And see the shapes
Made by the clouds
And they go wandering by

To picture things
That were not there
Or an imaginary ride
To lay down in
The earth-bound grass
And wish we were that high

The clouds I see
Stream out behind
A silver flash of steel
And they, too, paint
Their shapes for me
And pictures all too real

I see in them
Their destinations
And routes stretched far and wide
A giant web
Or complex puzzle
With mysteries inside

I imagine the places
To which they fly
And why they might endeavor
To leave behind
And streak ahead
And draw for me this feather

I picture things
That are not here
An imaginary ride
As I stand
Down here in earth-bound grass
And wish I was that high

I want to ride
That speck of steel
And visit destinations
‘Till I’ve seen
Them for myself
Not just my mind’s creations

But when I’ve ridden
Up with the clouds
I could not help but look
Down at the grass
And roads and cities
Like maps inside a book

I’ve often wondered
If behind my speck
I, too, a cloud was leaving
And if someone
Was looking up
And he, like me, was dreaming?

Dave Mark - Intrinsic Algorithm - Reducing the world to mathematical equations!
Posts: 8202
Joined: Mon May 24, 1999 1:12 am

RE: How Do Contrails Form?

Sat Jan 31, 2004 5:33 am

Great poem there Innocuous Fox.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz

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