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Post by dave on Feb 14, 2023 13:30:03 GMT
hi,
i've got a serious question for our large experten on this group, can anyone please explain to me, how when new aircraft deliveries and very interesting aircraft are about, the clouds always roll in? it happen today for the N547VL, and the same for N974NK on the 6th... then it clears up,
flustrated from Staffordshire...
regards,
dave...
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Post by lordevanelpuss on Feb 14, 2023 20:31:43 GMT
Sounds to me like a case of 'sod's law'.
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Post by chrisj on Feb 15, 2023 17:57:30 GMT
Yep ! I too find this problem - one we can do nothing about and have to live with unfortunately . Often , in the wilderness of North Devon , on a fair day I watch a plot of a 'wanted' frame as it draws closer . Then just as it gets to a point where I probably could see it - Them *&*&* clouds gather at Mac 2 , only to go just as quickly when the frame has passed any viewing point ! Very frustrating but ' That's Life' . Always one for another day . But I ask , In the days since 'Lock Down' aircraft , and particularly Biz Jets , have been flying at heights over 38 thousand feet . Why do they not trail ? If they do , then why can the trails not be seen ?? Also , why do we get thin grey cloud on what looks like a blue sky as this hides traffic ? Probably another one for 'Global Warming ' . Just a thought to help you get off to sleep ...zzzzzzzz ( All a bit light hearted ) Chrisj
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Post by dave on Feb 16, 2023 10:55:29 GMT
hi,
i used to have a website that told trailing heights, but lost it, but it is strange when we have a really cold day, they don't trail? and when you get to my age, health, following trails to the "gotcha" point is the only way...
regards,
dave...
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Post by lordevanelpuss on Feb 16, 2023 11:10:19 GMT
Please correct me if I am wrong on this, but I believe it depends on the surrounding atmosphere at the aircraft's altitude as to whether it trails or not, even down to how prolifically it trails and how long the trail persists for after the aircraft has passed by. If there is no trail behind an aircraft at an altitude of, say FL310, then it's probable that the atmosphere is very dry; similarly if there's only a short trail which dissipates very quickly. A long trail suggests a damper surrounding atmosphere, especially if it persists and spreads out. The latter could be the first warnings if coming poor weather after a fine spell. Hoping this doesn't send people to sleep  !! |
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Post by graham on Feb 16, 2023 12:25:19 GMT
I think you're correct Phil, we get loads of OTTs across here, sometimes they trail at FL320 and not at FL380 or vice versa. Hot exhaust gases will condense faster ( I think..) in wetter air, but the air for example over Greece where we go often is usually very warm and as such, planes rarely leave a con trail.
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Post by chrisj on Feb 16, 2023 20:26:35 GMT
I would say that the last two posts just about sum up the trail or not to trail thing . I recall quite some time back that one of the club magazines had some very deep details by someone who knew much on the subject . As is the way of these things - I have long lost it . But it is to do with the atmosphere at the aircraft height so we get height bands where trails are possible . I think the Dutch are trying to stop trails but I am not sure how . Chrisj
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Post by davebasing on Feb 17, 2023 12:37:29 GMT
Phil’s explanation for contrails is correct. They form primarily where the surrounding atmosphere is moist and at or below minus 40 degrees C. As Chris says however, there is pressure to reduce or eliminate the production of trails. This is because they have been proved to be a fairly major contributor to the aviation generated causes of global warming. As many of us dot-spotters will have seen, persistent trails can merge or fan out to cause the formation of cirrus clouds. While these have a cooling effect by reflecting sunlight, they have a greater warming effect by trapping heat radiating from the earth. The positive cooling effect however disappears at night and the effects become entirely negative. Thus red-eye flights become the worst culprits.
Much work is underway to seek a solution and/or to add the negative contrail effects to existing emission trading schemes under which airlines have to purchase credits for their emissions under the polluter pays principle. Problems arise not just with the forecasting of persistent contrail conditions on any given route but also how these areas might be avoided. The obvious solutions are either flying below the forecast contrail level or re-routing to avoid the forecast areas. Both however have downsides in that they result in additional fuel burn and hence greater CO2 global warming emissions. These also clearly have cost implications for operators and also ATC issues in that flying lower squeezes the available airspace which is often already congested. Also what if cloud layers already exist on part of a route forecast to be persistent contrail forming? The trapping effect is already there so the result is surely positive in that the only effect is reflecting sunlight, although it could be argued that the reflection would have taken place anyway due to the presence of clouds either above or below the aircraft and thus the effect is zero.
Charging operators is seen as a first step while the scientists and regulators battle with the issue. The level of any such charging will of course dictate whether it is such that operators will be encouraged to seek to avoid trailing. But in any event the pressure will not go away and, if anything, is increasing. As my main area of work is now in the field of aircraft noise and emissions I am, like it or not, involved in the ongoing process so sorry for the long explanation.
As for Dave’s problem in Staffordshire, I lived there for a time but solved the problem. I moved (it didn’t work however!).
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Post by dave on Feb 18, 2023 11:09:47 GMT
hi,
thanks for the explanation dave, i'm born and breed in Gods country (Staffs), and i will be here till my thread runs out, whenever that is, but on a personal note i more or less depend on trails, so, long may they trail... sorry...and to the planet. but china isn't helping, or the loggers in brazil.
regards,
dave...
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Post by davebasing on Feb 18, 2023 11:56:35 GMT
hi, thanks for the explanation dave, i'm born and breed in Gods country (Staffs), and i will be here till my thread runs out, whenever that is, but on a personal note i more or less depend on trails, so, long may they trail... sorry...and to the planet. but china isn't helping, or the loggers in brazil. regards, dave... Fully agree, aviation is a fairly minor contributor (albeit a contributor nonetheless) to the overall environmental problem but is unfortunately an easy 'political' target both for emissions and noise. |
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Post by lordevanelpuss on Feb 19, 2023 10:39:29 GMT
Yep ! I too find this problem - one we can do nothing about and have to live with unfortunately . Often , in the wilderness of North Devon , on a fair day I watch a plot of a 'wanted' frame as it draws closer . Then just as it gets to a point where I probably could see it - Them *&*&* clouds gather at Mac 2 , only to go just as quickly when the frame has passed any viewing point ! Very frustrating but ' That's Life' . Always one for another day . But I ask , In the days since 'Lock Down' aircraft , and particularly Biz Jets , have been flying at heights over 38 thousand feet . Why do they not trail ? If they do , then why can the trails not be seen ?? Also , why do we get thin grey cloud on what looks like a blue sky as this hides traffic ? Probably another one for 'Global Warming ' . Just a thought to help you get off to sleep ...zzzzzzzz ( All a bit light hearted ) Chrisj It's just happened to me here in Aldershot. So far it's been a lovely sunny morning. I was watching a PC12 on the radar coming my way and as I got outside there were patches of misty low cloud, thankfully I saw the aircraft in the breaks, even though I didn't need it. |
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Post by billsamuels on Feb 20, 2023 11:32:33 GMT
Good morning Chaps,
Well it’s probably no consolation fellas but having just spent the last 10 days vacationing in Barbados, I only saw one OTT that had an almost immediate dissolving trail… Boeing 767-316F PR-ABB Latam Cargo, for which I was very grateful, as I framed it…
But, I must admit, I share Dave’s frustration that at various times of the year, the lack of trails is very frustrating.
Dave’s (Basing) very in-depth explanation, and work challenges, is greatly informative, as usual.
Keep looking guys, it’s what makes our hobby so rewarding, when you see one!!!
All the best.
Bill
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Post by Jeff on Feb 22, 2023 19:38:22 GMT
I fear, as Dave has mentioned, trail will be a thing of the past in the near future 😕
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Post by lordevanelpuss on Feb 26, 2023 11:28:20 GMT
Yep ! I too find this problem - one we can do nothing about and have to live with unfortunately . Often , in the wilderness of North Devon , on a fair day I watch a plot of a 'wanted' frame as it draws closer . Then just as it gets to a point where I probably could see it - Them *&*&* clouds gather at Mac 2 , only to go just as quickly when the frame has passed any viewing point ! Very frustrating but ' That's Life' . Always one for another day . But I ask , In the days since 'Lock Down' aircraft , and particularly Biz Jets , have been flying at heights over 38 thousand feet . Why do they not trail ? If they do , then why can the trails not be seen ?? Also , why do we get thin grey cloud on what looks like a blue sky as this hides traffic ? Probably another one for 'Global Warming ' . Just a thought to help you get off to sleep ...zzzzzzzz ( All a bit light hearted ) Chrisj It's just happened to me here in Aldershot. So far it's been a lovely sunny morning. I was watching a PC12 on the radar coming my way and as I got outside there were patches of misty low cloud, thankfully I saw the aircraft in the breaks, even though I didn't need it. What is it about PC12s & clouds? It's happened again today, this time it was G-FITC that was in & out. At least I bagged today's one! |
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Post by andover on Mar 3, 2023 17:04:46 GMT
The following snip is from SAF Investor and includes a contrail paragraph that I have annotated >>> <<< below...
SAF is simply jet fuel. Pure jet fuel. This purity is why it cannot yet be used 100% in aircraft engines. Engine seals were developed to work with aromatics – impurities like naphthalene – and it is unclear how they will work with much purer SAF.
>>>The absence of aromatics means that SAF burns cleaner so produces fewer contrails – the European Union Aviation Safety Agency (EASA) has argued that aromatics should be removed from all jet fuel.<<<
Engine manufacturers are all working to make their engines work with 100% SAF but certification will take time.
Cheers
andover
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Post by michael on Mar 5, 2023 18:30:48 GMT
The met office is able to define the band that produces the contrail (to an extent)
This due to start a trial shortly at work by Easyjet on certain domestic flights of filing the cruising Flight level within the "no trail" levels to look at enviromental possible benefits.
Remember this is why (for obvious reason) U-2's have a wing mirror.
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Post by davebasing on Mar 5, 2023 18:51:15 GMT
The met office is able to define the band that produces the contrail (to an extent) This due to start a trial shortly at work by Easyjet on certain domestic flights of filing the cruising Flight level within the "no trail" levels to look at enviromental possible benefits. Remember this is why (for obvious reason) U-2's have a wing mirror. A very good trial was that carried out during the closure of US airspace for a few days after 9/11 when there were clearly no trails and which showed a definite temperature effect. Hope the met office plots corresponding pre-existing cloud cover as well, as that impacts on the potential effects as does the issue of any additional fuel burn (and hence additional climate change emissions) by flying at sub-optimal levels. |
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