Vapour Trails and Greenhouse Gas

[Pub User]

Several of the posts above have mentioned this water that is "injected" into the atmosphere by jet engines. Unless my jet-engine theory knowledge is seriously flawed, there is no water "injected" by the engine into the atmosphere (except for a few seconds during the Harrier's hovering antics). The water vapour/ice crystals are simply gathered by the hungry engine and pushed out in such a concentration that they are visible.

Additionally, the fundamental argument that cloud cover produces a warmer Earth is utter rubbish. Last Friday it was 32deg C in my garden, but on Saturday we had cloud cover and it only reached 26. Or is it just Cirrus that warms the Earth, and all other clouds keep the heat out?

[Ignition Override]

If there is some pollution, then that is simply too bad. But our industry should be left alone-it is having a difficult enough time recovering (at least in the US) from TOO MUCH GOVERNMENT, i.e. those huge security taxes, which are not paid by the passengers. We have many thousands of airline people laid off, and this only includes the US. Yes, the US government recently paid the airlines back, at least for part of this, but just wait-our GOP is quickly closing the gap to become so over-regulated that it already appears to operate like the many heavy-handed foreign govts out there, which seem to believe that a gigantic bureaucracy with rigid regulations for everything, is more efficient than anything else.

Ozone or pollution-that's just tough. This issue should go to the very bottom of the problem priority list-whether the Green Party (i.e. German Foreign Minister Joschke Fischer) likes it or not. Many of them would rather live in the Iron Age in a village and/or in total anarchy. Maybe that is why so many anarchists/Communists are attracted to this party....("brilliant deduction, Einstein")....

[bluskis]

Pub User

Fuel contains carbon and hydrogen amongst other elements.
Air contains nitrogen and oxygen amongst other things.

Reacting fuel and air in your jet engine results in the oxygen in the air combining with the carbon and the hydrogen in the fuel , forming carbon dioxide and water, again amongst other things.

[bookworm]

I didn't see any links to the papers in the preceding thread, so for those interested in reading the original research rather than dismissing it on the basis of an article written about it:

Reducing the climate change impacts of aviation by restricting cruise altitudes

and the more recent paper by the same authors with a more detailed analysis of the fuel burn consequences

Air Transport Cruise Altitude Restrictions to Minimize Contrail Formation

[Pub User]

bluskis

You're right! I knew I should have concentrated harder in those Organic Chemistry lessons in sixth-form, but the girl opposite had such lovely legs ...........

I'll take the hit on that one, but while we're into chemical equations, what about the other one (cloudy day = warmer weather). I know about the change in diurnal variation with cloud cover, but the simple fact is that a cloudy day is a cold(er) one.

[bookworm]

The IPCC report goes into some detail on the effect of cirrus cloud and contrail on warming. The key is that on average they keep more heat in than they keep out.

[Pub User]

A fascinating article, if a little unwieldy in its prose. However, it uses the word "may" no less than 24 times to present its case. This is hardly likely to convince any audience, particularly one consisting of professional pilots, who are used to dealing with practicalities any certainties.

NotsoFantastic tell us, above, that his 747 WILL use (approx) 16% more fuel if he flies at the levels recommended by the scientists. His company is not going to even think of allowing such measures without strong and persuasive facts.

Piloting is one of the few occupations in which one is required to take true responsibility, or put your money (life) where your mouth is. If scientists want to convince these people, they will have to have significantly more conviction than the author of the article has demonstrated.

[bluskis]

A little weighty in its prose is being polite.

Congratulations Bookworm for having the patience to read through it and precis it so concisely.

I can just picture the multilingual committee negotiating and voting on each and every paragraph in committee English, and squeezing their mates into the footnotes.

Still, as somebody remarked earlier, global warming has become an industry.

[Pub User]

Perhaps the precis was a little too concise.

Surely what Bookworm meant was: ".........they may keep more heat in than they keep out."

[TyroPicard]

Pub User

But cloudy nights are warmer than clear nights.

TP

[used2flyboeing]

This is a hugh issue - to add with the other two hugh issues ( 1) noise 2) emissions ) facing new aircraft designs - particularly HIGH ALTITUDE aircrafts, MULTI-ENGINE aircrafts - and MOST IMPORTANTLY - HYDROGEN POWERED AIRCRAFTS. ..I think Boeing has done a study on this - the problem with HYDROGEN & LOTS of HIGH ALTITUDE AIRCRAFTS is that the former GENERATES WATER VAPOR the persists at altitude for a very long time - now, if you load up the skys with these things - they could effectively start to impact the solar radiation comming through .. Now, if you are business paranoid Boeing - this is something else to mitigate a 10-30 billion new airplane strategy - There is still cold war nuclear bomb fallout persisting at very high SR71 altitudes - so everything that goes up - takes awhile to come down.. I knew a British air force engine mechanic who had significantly gotten exposed to distilled radiation - due to cleaning engine exhaust nozzles on high altitude British bombers or reconnassiance aircrafts during the 70s80s. Another big risk factor for the A380 is noise - risky to but 4 very large engines on an airplane in view of future unknown noise & emissions standards..