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Thermit
Joined: 08 Jul 2000
Posts: 3136
Location: Texas |
Another Megasprayer?
 Wed Jul 25, 2001 4:17 pm
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http://www.carnicom.com/submit1.htm
quote:
Both photos are of the same plane just a few seconds apart. The photos were taken on July 5 at approx. 9:00AM in Diamond Springs, CA. the plane approached from the South heading North. It sprayed for approx. 30 seconds, 10 seconds before I took the photo and about 20 seconds after. The trail that it left for that 30 seconds eventually turned into a high cirrus cloud that persisted for several hours. The relative humidity for sacramento at 300mb on July 5 was approx. 67%. Notice the white spray coming from the wings between the engines and the cabin."
"I'm sending you the uncropped picture of the Megasprayer I sent you. I thought it might be helpful in determining altitude. I believe it is a Boeing 757 series 200 with an overall length of 155ft. 3in. The print is 4by6 inches and as you recall was shot with 1000 mm lens."
Any confirmation or alternate conclusion on the plane make/model? |
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Lulu
Joined: 22 Dec 2000
Posts: 2501
Location: right here |
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Wed Jul 25, 2001 4:36 pm
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Call me relative humidity challenged, but doesn't the relative humidity have to be 100% in order for contrails to persist? How can a high cirrus cloud that persisted for several hours happen at all given the percentage of relative humidy at that time? Unless of course, these aren't your average friendly ice crystals spewing out of the wing tips...
[Edited 2 times, lastly by Lulu on 07-25-2001] |
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3T3L1
Joined: 08 Mar 2001
Posts: 1344
Location: Lubbock, Texas |
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Wed Jul 25, 2001 4:49 pm
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Actually, no, Lulu. Check out this graph from the Science Forum:
Contrails (and water droplets) form when the saturation vapour pressure with respect to liquid water is exceeded. They persist when the air is saturated or supersaturated with respect to ice.
http://www.royal-met-soc.org.uk/weatherclub/secondary/scisky3.html |
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Lulu
Joined: 22 Dec 2000
Posts: 2501
Location: right here |
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Wed Jul 25, 2001 5:01 pm
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Thanks 3T3, I had seen your chart earlier, great work you're doing in the science forum btw! My confusion it seems is with the conditions in which the contrail forms as apposed to the conditions for persistence. |
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Duncan Kunz
Joined: 19 Oct 2000
Posts: 582
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Wed Jul 25, 2001 6:59 pm
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If the aircraft shown is a Boeing product, it could only be one of four models which are twinjets with the engines mounted on the wings: 737, 757, 767, and 777. Given the placement of the wings, i.e., about halfway between nose and tail, I can eliminate the smallest aircraft: 737-600.
But given the lack of hard data regarding the aircraft's altitude and azimuth relative to the photographer, it's extremely difficult to differentiate between the 110-feet-long 737-700 and the 242-feet-long 777-300.
I have looked at the underside of the wings of the aircraft photograph; despite me seeing the engine and engine supports clearly, I do not see any evidence of longitudinal strakes beneath the wings. With the 757, 767, and 777 models, these strakes are quite large, and they (or the shadows cast by them) should be visible in the photograph. They are not.
Another possibility is that the aircraft in question is an Airbus Industrie A320-class (-318, -319, -320, -321 variants) or the larger Airbus A300- / A310-class (twin-aisle variants) however, they, too, are fitted with longitudinal strakes under the wing surfaces; moreover, their engine nacelles seem to be placed further forward on the wings thatn the aircraft in the photograph.
So what can it be? Well, if it's not an Airbus or a Boeing aircraft, that doesn't leave anything I can think of (Lockheed and McDonnell Douglas aircraft to not fit the configuration at all). So obviously the aircraft must be one of those mentioned above.
But, as I said earlier, given the lack of atlitude/azimuth data and the inherent graininess of the photograph, there is no way I can think of to identify the aircraft even to the manufacturer level, say nothing of the particular model.
Regards,
Duncan Kunz
The Boeing Company
Mesa, Arizona
480-891-2525
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3T3L1
Joined: 08 Mar 2001
Posts: 1344
Location: Lubbock, Texas |
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Wed Jul 25, 2001 7:33 pm
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Lulu, as I understand it, when exhaust gases leave the plane's engine, they are hot and contain water vapor from combustion of the fuel. As the exhaust cools, its water vapor, plus the water vapor already in the atmosphere, can bring the relative humidity to 100% in that immediate location, and water droplets will then condense into a contrail. At -40°C, the droplets will then freeze into ice particles. Whether the frozen contrail particles PERSIST, however, depends on the relative humidity with respect to ICE.
(By reading a meteorology textbook, I learned that fine droplets of water vapor do not freeze at 0°C, but actually remain in the liquid state until they reach about -40°C. It sounds counter-intuitive, doesn't it?)
[Edited 1 times, lastly by 3T3L1 on 08-05-2001] |
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theseeker
Joined: 25 Jul 2000
Posts: 3403
Location: Damnit...I'm a doctor jim |
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Thu Jul 26, 2001 1:45 am
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Both photos are of the same plane just a few seconds apart. The photos were taken on July 5 at approx. 9:00AM in Diamond Springs, CA.
Ahemmm, but is it visually darker at 9:00am in diamond springs california, than everywhere else ? |
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theseeker
Joined: 25 Jul 2000
Posts: 3403
Location: Damnit...I'm a doctor jim |
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Sun Jul 29, 2001 10:23 pm
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I found this photo of wing-tip vortices and some of that under the craft vapor that looks similar to carnicom's....naturally this photo is un-touched...
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theseeker
Joined: 25 Jul 2000
Posts: 3403
Location: Damnit...I'm a doctor jim |
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Mon Jul 30, 2001 12:37 am
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another excellent photo...
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Chem11
Joined: 21 Apr 2001
Posts: 1386
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Sat Sep 01, 2001 10:51 am
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While eyeopen's megasprayer footage depicts a much more defined trail, I'd like to point out the similatities between the two as far as the prismatic effect visible in the trail in both Cliff's pics and the long version of the mpeg.
The most recent arguement to have been made is that the the perspective of the witness has caused the illusion of four seperate trails to appear as one. However, in these photographs, this is not the case. And yet both examples depict this anomalous prismatic effect. This rare effect leads me to believe that we are witnessing the same causitive factor in both examples.
The same effect can be observed in 'sun-dogs' and 'sun-rings' that occur during heavy spraying.
Something is causing spectrum-filtering in the atmosphere and it is being dispensed by these jets.
[Edited 1 times, lastly by Chem11 on 09-01-2001] |
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Chem11
Joined: 21 Apr 2001
Posts: 1386
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Sat Sep 01, 2001 10:55 am
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Note: this primatic effect is not present in either of the examples of aerodynamic vortices posted above by theseeker. |
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Dirk Digler
Joined: 16 Mar 2001
Posts: 126
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Sat Sep 01, 2001 4:55 pm
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ok folks, i'll chime in on this one as i am pretty familiar with this aircraft :~)
it definately is a boeing 757 producing classic aerodynamic contrails. this is exactly what they look like when you see them up close. as a matter of fact, this could be a text book picture demonstrating these type of contrails. you see this alot during a climb when the wings are producing a ton of lift. as a matter of fact, the 757 is really good at this as their wings produce a hell of alot of lift. they actually have different seperation criteria because of the wake turbulance that they produce.
duncan mentioned that he couldnt see the flap fairings. this is because of he resolution of the pic. they are there.
DD
[Edited 1 times, lastly by Dirk Digler on 09-01-2001] |
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