PPRuNe Forums

PPRuNe Forums (https://www.pprune.org/)
-   Rumours & News (https://www.pprune.org/rumours-news-13/)
-   -   Upper Atmosphere pollutions... (https://www.pprune.org/rumours-news/612039-upper-atmosphere-pollutions.html)

Chocks Away 10th Aug 2018 11:29

Upper Atmosphere pollutions...
 
Ladies and Gentleman I pose an honest and interesting question, to those of you hopefully closer to the core of this question... (NASA hopefully) because I'm very tired of being hit by the left wing media spewing-on about airline pollution in the upper atmospheres. It contradicts what I heard from one of the NASA Global Express Atmosphere Test pilots I spoke to face to face in Christchurch / EnZed, many years ago.

This is the latest slanted story on what I speak of and it lacks... everything, basically!
Scram jets' fuel requirements and upper atmosphere propulsion diminishes the higher you get doesn't it?

In discussions with the NASA pilot I'd spoken of previously, their findings were (being at the last section of their global trip I believe) findings were that jet engine emissions above the Tropopause/ jetstreams were found to have been beneficial, while those below where otherwise.
Can someone with expertise please swipe the politics into the bin and give the true Facts? ("Handing over") :ok:

.Scott 10th Aug 2018 11:39

Jet aircraft, and the contrails they create, definitely have a more-than-noticeable effect on the weather.
See this story:
What happened to the weather when the skies went empty.

Data indicates that contrails reduce the day/night temperature range.
But the effect is due to water vapor, not CO2. So the results persist only for as long as there is aircraft activity - then dissipate in a matter of a day or two or three.

This was noticeable in the US after the 9/11 shutdown of the North American airspace. And since then, I have taken closer looks at cloud formation and noticed that it is common for high clouds to be dominated by a criss-cross pattern that most likely evolved from contrails.

There is also an issue of ozone.
Nitrogen Oxide emissions from jet aircraft create ozone in the troposphere, but assist in its destruction in the stratosphere. Jets are flying higher to save fuel and are spending more time in the stratosphere.
I don't know of anyone tying this to a measured drop in the ozone layer. I found a 20-year-old article from "New Scientist" that suggested there might be a real problem, but that is not enough to convince me. I would be much more impressed with an article from "Nature", "Scientific American", or perhaps NASA. But articles from those groups do not suggest there is anything to be concerned about.

Finally, there is CO2. Of course, aircraft create CO2 - and in the next decades we could be seeing SSTs which produce more CO2. But this is not a problem specific to aircraft.

Chocks Away 10th Aug 2018 15:18

Brilliant input thanks Scott and you jolted my memory into something he said.

Nitrogen Oxide emissions from jet aircraft create ozone in the troposphere,
He mentioned the global results showed this huge trend which was repairing the Ozone layer in the Southern Hemisphere especially, (along with changes of spray can repellents etc) but there was still a huge hole reaching up over NZ, though reducing. (sic).

P.S. No CONTRAIL CONSPIRACY floggas here please!

climber314 10th Aug 2018 15:52

Interesting read about the post 9/11 effect. I am suspicious of the Penn State study given the following at the bottom of the linked article:
"The National Science Foundation supported this work."

I think they have an agenda.

"A Penn State study compared regions of the United States where contrails tended to form more strongly with areas where they didn’t. The more contrail-heavy the area, the less the variation between daytime highs and nighttime lows tended to be."

wiedehopf 10th Aug 2018 17:09


Originally Posted by climber314 (Post 10220157)
"A Penn State study compared regions of the United States where contrails tended to form more strongly with areas where they didnít. The more contrail-heavy the area, the less the variation between daytime highs and nighttime lows tended to be."

That approach is really stupid. Moisture content is higher --> contrails form and the variation is lower.

Great study confusing causality and correlation.

Ian W 10th Aug 2018 18:11


Originally Posted by .Scott (Post 10220011)
Jet aircraft, and the contrails they create, definitely have a more-than-noticeable effect on the weather.
See this story:
What happened to the weather when the skies went empty.

Data indicates that contrails reduce the day/night temperature range.
But the effect is due to water vapor, not CO2. So the results persist only for as long as there is aircraft activity - then dissipate in a matter of a day or two or three.

This was noticeable in the US after the 9/11 shutdown of the North American airspace. And since then, I have taken closer looks at cloud formation and noticed that it is common for high clouds to be dominated by a criss-cross pattern that most likely evolved from contrails.

There is also an issue of ozone.
Nitrogen Oxide emissions from jet aircraft create ozone in the troposphere, but assist in its destruction in the stratosphere. Jets are flying higher to save fuel and are spending more time in the stratosphere.
I don't know of anyone tying this to a measured drop in the ozone layer. I found a 20-year-old article from "New Scientist" that suggested there might be a real problem, but that is not enough to convince me. I would be much more impressed with an article from "Nature", "Scientific American", or perhaps NASA. But articles from those groups do not suggest there is anything to be concerned about.

Finally, there is CO2. Of course, aircraft create CO2 - and in the next decades we could be seeing SSTs which produce more CO2. But this is not a problem specific to aircraft.

This is a very very poor example. There are many days when you see no contrails it all depends on humidity. So contrailing is not the issue.

9/11 if you remember back then was a CAVOK day with a dome of high pressure over the East Coast dragging cool air down from the North the high was persistent. It would have been cool anyway one of those fresh pre-fall weeks that happen occasionally. It had nothing to do with the lack of aircraft which would not have left contrails anyway. The researchers involved would have had a different result if they had looked for an analog week with the same pressure set up in previous years. But it made for a good press release.


All times are GMT. The time now is 15:29.


Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.