What are Contrails?

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What are Contrails?

Post by Advisor »

Contrails

Contrails are line shaped clouds or “condensation trails,” composed of ice particles, that are visible behind jet aircraft engines, typically at cruise altitudes in the upper atmosphere.

Depending on the temperature and the amount of moisture in the air at the aircraft altitude, contrails evaporate quickly in the humidity is low or persist and grow in the humidity is high. Jet engine exhaust provides only a small portion of the water that forms ice in persistent contrails. Persistent contrails are mainly composed of water naturally present along the aircraft flight path.

Aircraft Engines emit water vapour, carbon dioxide (CO2), small amounts of nitrogen oxides (NOx), hydrocarbons, carbon monoxide, sulfur gases, and soot and metal particles formed by high-temperature combustion of jet fuel during flight. Of these emittants, only water vapour is necessary for contrail formation.

Some questions which need answers, are:-
•How do contrails form?
•What are the ingredients of jet fuel, and are they important to contrail formation?
•Are persistent contrails harmful to the public?
•Do authorities regulate aircraft emissions?
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Post by Advisor »

I hear that there is a proposal that the airlines will be taxed on their CO2 and NOx emissions!
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SN30952
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Les différentes traînées d'un avion

Post by SN30952 »

Here is a site Les différentes traînées d'un avion unfortunately only in French, that explains a lot about thes contrails.

Items explained:
1 - la traînée
2 - Le coefficient de traînée
3 - La courbe de traînée
4 - La traînée d'aileron
5 - La traînée de choc
6 - La traînée de couche limite
7 - La traînée de forme et coefficient
8 - La traînée de frottement
9 - La traînée de profil
10 - La traînée d'onde
11 - La traînée induite
12 - La traînée minimale

Who's able to translate that?
Last edited by SN30952 on 21 Dec 2004, 14:08, edited 1 time in total.

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Post by Bruspotter »

Hello Advisor and the rest!

At this time of the year weird enough the sky is clear (nicer
weather than in the summer often) , but cold.

It's than when you can spot a lot of 'contrails' as they appear
and i have time , i'm glued to the sky. I watch every passing plane
and try to identify as much as possible. In this time of the year
it even looks more busy than in the summer, high in the sky.

It looks like the FRA-America route is again above my house
(badly enough probably only for a short wile).

I can enjoy spotting contrails even as much as spotting next to the
runway, and much more interesting planes.


Anyone else spotting contrails?

Best contrail spotting Christmas regards: Yannick :D :D :D

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Re: What are Contrails?

Post by Avro »

Advisor wrote: Some questions which need answers, are:-
•How do contrails form?
•What are the ingredients of jet fuel, and are they important to contrail formation?
•Are persistent contrails harmful to the public?
•Do authorities regulate aircraft emissions?
You'll find some answers on the following link: https://www.aviation24.be/postlite3493-contrails.html

There isn't a simple formula for jet fuel but let's just say that it is CHy (I don't think that the chemical poeple among us will object ;) )

The reaction of the combustion can be simplified and written as follows:

CHy + w(O2 + 3.76N2) -> a0*O2 + a1* CO + a2*CO2 + b1*H2 + b2*H2O + 3.76w*N2.

- NOx can be created, because of the oxidation of N2 due to the high temperatues or when the fuel contains Nitrogen as well in its composition.
- the same is happening with the sulfurs. But those parts of the products are very small in comparison with the other products.

Now to the question if only H2O is contributing to the building of contrails, I would say yes. Why ? Because to get contrails the gas has to transform itself into small droplets or small ice crystals.
If we assume that the temperature at 10000m is approx -50 and compare this value to the temperature where the components become liquids (don't know the name in English sorry, André might help ;) )
We clearly see that only H2O will be able to transform itself.
•Are persistent contrails harmful to the public?
What do you mean with persistent contrails ? They never last forever. But some of them might stay for a long time in the skies.

Chris

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Post by Advisor »

Thanks for sharing the information with me friends. I remain grateful.
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Post by Advisor »

I also hear that at the recent 35th Assembly of the ICAO many European States have suggested that the Airlines be charged for their CO2 or NOx emissions, starting 2007.

It was declared at this assembly that 3.5% of all man-made greehouse gas emissions come from Civil Aviation.

So the debate now rages that 96.5% of the pollution that comes from other population is exempt is a clear discrimination.
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Post by Avro »

As a side note: The gas which has the mos tgreenhouse effect is not CO2 as many might think but simply H2O.

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Post by SN30952 »

Avro wrote:As a side note: The gas which has the most greenhouse effect is not CO2 as many might think but simply H2O. Chris
Some years ago in such a conference I was told that the production of hamburgers for the Mc Donald's, and other hamBurger Kings, caused more gas emissions than civil aviation. Cattle seems to produce an awful lot of gas.

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Post by Advisor »

Cattle seems to produce an awful lot of gas.

What kind of gas!!!!!
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Post by Avro »

Advisor wrote:Cattle seems to produce an awful lot of gas.

What kind of gas!!!!!
A little bit of N2O, a lot more CO2 and a huge amount of CH4

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Post by Advisor »

:surprised: No wonder despite having less planes, we still have a lot of gas around in India. :wink: Cattle everywhere!
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Post by Avro »

Advisor wrote::surprised: No wonder despite having less planes, we still have a lot of gas around in India. :wink: Cattle everywhere!
Not only the cattle ;) The humans produce as well a considerable amount of those gases. And in India the population density is quite high...

Chris

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Post by 1V1 »

About a month ago I made this pic. Never seen them like this.
greetz
JC
Image

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Post by Rago »

fantastic JC!!!

:banana: :banana: :banana:

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Post by Advisor »

Thanks for sharing JC.
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Post by Avro »

1V1 wrote:About a month ago I made this pic. Never seen them like this.
greetz
JC
Image
Great shot JC.

Could it be that two planes followed each other quite quickly and that one of them flew right into the contrals of the other one ? Because I would tend to say that you can see the vortex generated by a plane in those contrails....

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Post by Advisor »

VORTEX is the correct word.

I salute you thee CHRIS!
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Post by Wesley »

Hi all, my name is Wesley and my website is www.chemtrails.nl
It looks like you don't know yet what chemtrails are about, this website is a good one to start with the investigation: www.carnicom.com/conright.htm

Here a post from someone else, who has the same challenge in mind lik i have on my site 'De Uitdaging' (for the ones here speaking/reading dutch)

It goes like this:

============================================================
"I would like to comment on the "chemtrail" issue. I have been observing the spray planes over our skies here in the Pacific Northwest (Eugene, Oregon) for about two years now. Before that, I do not recall seeing a single contrail, ever. And, I must add, unlike most people today, I watch the sky and have an interest in everything that happens there from weather patterns to astronomy, aircraft and satellites. I have been doing this since I was a boy growing up near Chicago, a few miles from O'Hare Airport. I have a degree in Aeronautical Engineering from the University of Illinois so I am not without some knowledge of this subject.

I would like to suggest a challenge to those who think that these contrails are "normal." I challenge anyone to go through their family pictures, films and videos that were shot before, say 1990. Come up with pictures that show contrails like we see today in our skies. I don't mean a single, short contrail as one might see on a rare occasion but the extensive grid patters, "X's" and collections of parallel trails that we now see nearly every day. Any takers?

Paul S. Szymanski
Eugene, Oregon"

============================================================

I received only one picture from one person, from the year 1985, he called it 'Mysterious lines" because he didn't see that before and didn't after for many years till chemtrails appeared daily.

I do remember, that i didn't see trail lingering in the skies for hours, and i watched the skies long enough to know. How about you and the challenge?

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Post by Wesley »

I would like to add something, nice al those information on the Internet about contrails, but what about information on contrails documented before, let's say, 1990? I would like to see that and talking about it is possible that contrails can last for hours in the sky.
Thnx

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