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Wed 13 Oct, 2004 09:22 am
Are airline contrails contributing to global warming?
http://asd-www.larc.nasa.gov/GLOBE/contrails/
while interesting theory, there is perhaps weak scientific conjecture so far:
listed on the link page is the following:
"Q: Do contrails drastically affect weather patterns?
A: Originally scientists believed that the contrails behaved like cirrus clouds to actually make the climate warmer. However, there have been studies conducted that have scientists rethinking their earlier ideas about contrails.
This is one of the major questions that has to be researched at NASA and one of the reasons we are putting so much emphasis on contrails. When air traffic over the US was halted after the 9-11 incident, scientists got a rare look at the skies with only a few military jets flying. They were able to analyze the effects of some of these contrails and realized that their earlier notions about contrails' effects were not totally accurate. "
Moreover, from the same FAQ info from the hyperlink provided from the author of this query:
"Q: Has there ever been observation of rain from contrails?
A: Typically, rain clouds are low level clouds which are made up of water molecules. These water molecules then come together to form water drops (liquid) which eventually fall to the ground as rain drops. Since contrails are high level clouds, the moisture within them forms ice crystals which do not come together to form any form of precipitation (rain). "
ragman(orig)
Thanks, Ragman, for contributing information to this issue. We obviously have a lot more to learn, but at least it is a start in understanding what we humans are doing to our planet.
BBB
APoD was talking about this today..
Astronomy picture of the day 10-13-2004
I really love that page. I pretty much start out every day im on the web there and have learned a TON. Following the links they provide you can get to a lot of good information if you haven't seen it.
Seems that at the moment the contrails aren't making a huge difference, but a difference none the less. I read over area with high air traffic it can effect the temperature as much as a degree celsius even at night due to the change in albedo. I think it is good they are looking into this now as it seems it will increase in the future.. A page that is linked from APoD today explains a bit on that..
American Geophysical Union
I get interrupted so much when trying to post I missed what Ragman had said - I would think this would be very difficult to study so it's good they are still tossing around the idea and hopefully it's not making as big a difference as they thought. Does seem like it wouldn't make a huge difference really when you think about it, found it very interesting that it might.
No matter what though, seem there are bigger things to worry about concerning what we're doing to the planet.
I don't buy into this to much
Quote:Planes could not find their targets, and sometimes collided with each other
Well we better start eating more beef - to get rid of Cows - they do more harm than contrails
BumbleBeeBoogie wrote:Are airline contrails contributing to global warming?
While pursuing my own graduate studies, I knew a meteorologist who earned his doctor's degree with work on exactly this question. His answer turned out to be "very unlikely".
The contrails are partly carbon dioxide and water vapor which contribute minutely to green house warming. Cow farts and burps contain some methane gas which likely contributes less to green house warming than contrails. Both may be negligible according to about 99% of the scientists, and engineers. Admittedly the scientists who are alarmed are mostly specialists in related fields, so they should know.
edit; For the minutes the contrail is visible, it is reflecting solar energy back into space which cools the land under the contrail. Some of this reflected energy is absorbed in the upper atmosphere, making the polar down draft minutely warmer, but all these effect are likely close to negligible. Neil
Methane released as a by-product of human activity is proportional to population.
This paper is an
estimate of total emissions, and indicates a four-fold increase over the last century:
Quote:Total estimated anthropogenic methane emissions rose from 79.3 million metric tons in 1860 to 371.0 million metric tons in 1994.
source
The problem with contrails is not the release of pollutants, but the physical effects of the trail itself. Here's a NASA image of:
Quote:widespread contrails over the southeastern United States during the morning of January 29, 2004. Such satellite data are critical for studying the effects of contrails. The crisscrossing white lines are contrails that form from planes flying in different directions at different altitudes. Each contrail spreads and moves with the wind. Contrails often form over large areas during winter and spring.
That site.. Earth Observatory, is awesome! Thanks very much for that link Mr Stillwater. I can tell im going to be lost in there for a while.
Clouds contribute to planetary cooling, not warming, most aircraft aloft forming contrails don't belong to airlines, and the link bears no connection to the question.
The "Science and Mathematics" forum has low admission standards - presumably traceable to yet another error in the education policy of the current administration <G>
Hamal wrote:That site.. Earth Observatory, is awesome! Thanks very much for that link Mr Stillwater. I can tell im going to be lost in there for a while.
My pleasure. You can also get onto Space.com for some of the most incredible images of working space-craft! Not exactly Star Trek, but inspiring all the same.
Yes space.com is a good one I have looked through, I agree. Im just blown away by the satellite shots of the planet showing the current fires, flooding, storms, volcanic activity, ect. on the Earth Observatory site. All coming with at least a bit of explanation or back ground info, very cool.
This was definitely not to take away from the site that BumbleBeeBoogie posted originally. I really appreciate you starting this thread. I think it's the best way to find links to interesting stuff on line. A long while back it is exactly how I found APoD and have been a huge fan of that site ever since. Anyway cheers~
Hi HofT: I'm inclined to think you are correct, but the elete science guys tend to be very arogant and very conservative, so most break thoughs are made by persons who don't know that what they are attempting is impossible. Neil
The 4 fold increase in methane released into our atmosphere as a result of human activity (if it occurred) is not a big deal as nature emits far more methane and it typically becomes water vapor and carbon dioxide in a few days, which are released by nature in huge quantities. The bottom line is humans likely contribute very little to the tiny amount of global warming that has occurred in the last century and the last few decades. Neil
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