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goldrush
Joined: 04 Sep 2000
Posts: 109
Location: No, Calif. USA |
 Fri Oct 27, 2000 6:49 am
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Glory be, that is the kind of article that posits the question that NASA is yet studying. It caters to the current administration, and bases its theory upon projections upon a static aviation technology from three years ago. Read up, NASA is investigating causes of global warming that go beyond areas of human influence, or political hand-slapping. I am a little too lazy at the moment to bring up and transcribe some of the info I have read in the past weeks that shed light upon solar influences, and the complexity of tropospheric chemistry, but a change in administration eventually, hopefully will not bury what other factors should be included, before global credit exchanges become an acceptable idea. I was very happy to hear G.W. not embrace the Kyoto Treaty, when the subject came up in the second debate. I have an automatic suspicion of projections, because all too often, they are images of what the authors want you to see, and not even close to what really happens. |
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cydoniaquest
Joined: 12 Aug 2000
Posts: 797
Location: nowhere |
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Fri Oct 27, 2000 8:27 pm
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DELETED BY THE ARTIST FORMALLY KNOWN AS CYDONIAQUEST
[Edited 1 times, lastly by cydoniaquest on 01-13-2001] |
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canex
Joined: 26 Oct 2000
Posts: 164
Location: USA |
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Fri Oct 27, 2000 9:46 pm
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To Thermit:
Unfortunately, the Hanson and Hanson reference is not the greatest for determining contrail formation. A paper by Ulrich Schumann ("Contrail formation from aircraft exhausts," Meteorologischen Zeitschrift, Vol. 5, 1996, pp. 4 - 23 ) is probably the best one out there for giving a technical overview of contrail formation. There is no particular simple formula for determining the threshold temperature for contrail formation at a given pressure altitude. A series of non-linear differential equations describing the thermodynamics of formation is necessary to arrive at the threshold temperatures. These can be solved iteratively, but can also be approximated with a series of linear equations that require several variable inputs like engine efficiency factors, fuel hydrogen content, ambient water vapor mixing ratios, pressure, and temperature. Some simple curves can also be constructed for various values of relative humidity. These equations can be found in the appendix 2 of the Scumann paper. Also included in that paper is a plot showing the thresold temperatures for contrail formation for a particular fuel efficiency and several ambient relative humidities. In that plot, a temperature less than -42C or 231K is required for contrail formation when RH < 100%.
Persistent contrails will only occur when the ambient RH with respect to ice (RHI) > 100%. Thus, one should expect persistent contrails the Schmidt-Appelton criteria (threshold temperature for contrail formation) are met and the RHI > 100%. I will provide that fromula whenever i can dig it up.
[Edited 1 times, lastly by canex on 10-27-2000] |
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Nola30
Joined: 22 Jul 2000
Posts: 41
Location: Tuscaloosa AL U.S.A. |
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Fri Oct 27, 2000 10:26 pm
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Elvis,
I am not disputing the FACT that aircraft put out exhaust and "normal" condensation trails. I am saying that I have witnessed these sprayers, as I have come to call them in action. They are spraying something, that at first appears to be condensation trails. Then it spreads out and forms fake cloud cover. Any cloud that forms due to something that people are doing or causing is not a natural cloud. I guess you will argue with that too. I don't know what it is they are spraying, but they are spraying something and it forms fake rusty- murky looking clouds. What-ever it is, it could not be a good thing or who-ever is doing it would want the credit. Try as you may, you cannot change my mind. I trust my own eyes more than you or any of the rest of these self -proclaimed experts.
BTW I have never claimed to be an expert on the matter. I am just reporting what I see in my area. |
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cydoniaquest
Joined: 12 Aug 2000
Posts: 797
Location: nowhere |
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Fri Oct 27, 2000 10:30 pm
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DELETED BY THE ARTIST FORMALLY KNOWN AS CYDONIAQUEST
[Edited 1 times, lastly by cydoniaquest on 01-13-2001] |
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Thermit
Joined: 08 Jul 2000
Posts: 3136
Location: Texas |
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Fri Oct 27, 2000 10:40 pm
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Thanks Canex, will be looking forward to seeing the Schumann equations.
Still wondering about the 0-5 and 5-7 degree difference between temp and dewpoint guides...are they applicable to only a given range of altitudes, or somewhat universal?
Really appreciate you digging up the information...
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Thermit
Joined: 08 Jul 2000
Posts: 3136
Location: Texas |
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Fri Oct 27, 2000 11:01 pm
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Canex, Cy, et all, please see the new "Contrail Factors" thread for continuing the contrail discussion...
Click here.
Thanks. |
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