Aerosol Spraying Part 2.

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kendoyle
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Aerosol Spraying Part 2.

Post by kendoyle »

Lads,Ive begun a new thread as the other has descended into farce. I do feel this is a potentially genuine and serious issue.

I've spent a couple of days watching the skies and doing research.I may have found something of significance at one of Dublins smaller airports but I shall say nothing for now until totally confirmed and photographed.

In the mean time I would like you all to watch this video clip which illustrates 2 jets at the same time,one producing a more regular trail while another produces that which was laid down all over South Dublin last Sunday. I'm not sure how atmospheric conditions or engine type can explain the stark contrast here.

http://www.youtube.com/watch?v=Q9KLLqEL96Y&NR=1

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Post by Whisky Tango »

Ken, you're back! You never posted photos of your sighting from Sunday, where are they?

And do tell us what you saw at this smaller airport, maybe we can help you confirm it? Sounds very interesting...

As for that video, well there is a very simple explanation....one plane is smaller and/or higher than the other one. Although the witness states they're the same height, it's impossible for him to tell so you can throw that comment out for starters. There is a huge difference in the size and shape of contrails say from an A340 (4 engines) and a much smaller Learjet say (2 engines). Learjets are certified to fly at much higher altitudes than the A340, so what you're seeing is a smaller plane flying higher but further away than the larger plane, which makes them look the same height. I'm sure from your observations recently you can confirm that you saw several different forms of contrails, so nothing strange there then. Next time you're watching, log onto Airnavlive.com, put in EIDW as the airport and you can see all the planes in the vicinity (there's a lag of 5 minutes)

kendoyle
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Post by kendoyle »

As the video illustrates and as I witnessED ,this is not really an issue about lenght of trail but rather why some hang about all day and form gauzy clouds and others vanish within seconds.These are ,after all ,supposed to be simple ice crystals? Also what I witnessed started early morning and ended late at night.Presumably temperature and atmospherics had changed over the course of 14 hours yet the same phenomenon was witnessed...

Anyway,hope to have something solid and interesting soon regarding something I saw yesterday.

K

Ps. Nanolight uploaded my pics.

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Post by alphaLaura »

this is not really an issue about lenght of trail but rather why some hang about all day and form gauzy clouds and others vanish within seconds.These are ,after all ,supposed to be simple ice crystals?

This is, as you suspect, purely to do with upper-air mixing and conditions.
There's a process called sublimation which is what happens when a solid turns straight into a gas without visiting the liquid phase. (This is how "dry ice" works.)

If the air in the region of a passing jet is dry (i.e. if there is very little water vapour in it), then the ice crystals in the air will quickly sublimate into a vapour, and the contrail vanishes quickly. However, if the air already has a lot of water vapor in it, then the ice cannot sublimate as quickly so the contrail will slowly dissipate. The contrail will last longer. Then, at the extreme case, if the air has so much water vapor in it already that it can’t hold any more, then the ice crystals can’t sublimate, and so the contrail will stay around for a long time. The existing ice crystals can also act as a surface on which supercooled water can freeze onto. This causes the contrail to thicken.
Add in all the wind effects (both horizontal and vertical) and a contrail can spread during the day and merge with others to form a gauzy cloud layer.
On Sunday, like I mentioned, the warm front was decaying over Ireland but the weather was extremely stable all day - very little changes in pressure. This is why the contrails stayed put.

http://asd-www.larc.nasa.gov/GLOBE/reso ... oud_id.pdf

And as already explained by Whisky Tango, that video has two different jets at two different altitudes which produce two very different contrail formations.
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Post by OnTheNumbers »

There is nothing remarkable, other than the beauty of the sky, in that video. It's really simple, they are different aircraft in different part of the sky with different atmospheric conditions. If I may make an analogy. If you drop a pebble into a still lake the ripples will persist much longer than if you drop a pebble into a lake with a breeze blowing. If you want a more detailed technical explanation for the persistence of contrails, you'll probably have to talk to a meteorologist.

Everyone here is telling you this is normal variation. If you don't consider it normal, you'll just go and have to study high altitude weather for yourself - because clearly you're not content with the opinion general aviating public offered - many of who are very experienced aviators, some are even scientists.

Perhaps pprune my be a better place for your enquiry (sorry Mark)

David

[edited after AL's post] Or you could wait until someone like AlphaLaura very generously explains it for you.
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kendoyle
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Post by kendoyle »

I think we can only specualte at best that these are 2 different jets at two different heights.It is not possible to tell from the video.I find it almost incredulous tho that 2, so completetly different humidic atmospheric conditions are exisitng in what seems to be relatively close proximity to create the dramtatic contrast in this video.I don't see any culumis cloud in this shot either which would suggest a high humid condition required for long lasting trails.Also I have n ot found any papers yet describing contrails lasting for 12/14 hours.

The jets appear to be on a very similar trajectorty and so probably left the same airport I would hazzard. Contrail thickness also appears similar which again suggests that relative distances between craft where not that great.

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Post by Whisky Tango »

Ken, there are no cumulUs clouds because the atmosphere was under the influence of an anticyclone (High pressure system), and hence the air was subsiding (moving towards the earth), rather than ascending, which is needed to form cumulus. As the air subsides it heats adiabatically, so any liquid water evaporates, which is why highs usually (not always) have clear weather.

I suggest you read up on basic meteorology to get a grasp of these things, it may make things clear and you may see that what you saw was normal...I repeat, NORMAL!

PS Most of northern Europe's transatlantic traffic was tracking over Ireland Sunday so to say that the two planes were probably from the same airport is just ridiculous.

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Post by kendoyle »

I did find this paper linked to below. It states that for persistant contrails to occur a RHi of 100% isr equired and contrails that disappear in seconds are formed in dry conditions.So,again we have a video that appears to suggest that both a dry atmosphere and and atmpshere of 100% humidy are coexisting in much the same part of the sky...



Even if there were some distiance I doubt the humdity contrast was such to create the contrast in trails we see here.

"...After a short (about 1 s) initial growth stage (Kärcher et al. 1996), the contrail will evaporate within tens of seconds if the air is dry. In contrast, contrail growth will continue in background air that is supersaturated with respect to ice..."

http://ams.allenpress.com/perlserv/?req ... -0469(2000)057%3C0464%3AOTTOCI%3E2.0.CO%3B2&ct=1

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Post by vanman »

I find it almost incredulous tho that 2, so completetly different humidic atmospheric conditions are exisitng in what seems to be relatively close proximity
Why? That's the reality. Look at clouds, inside one it's wet and turbulent. Outside it isn't. Temperature and humidity can vary over small distances. That's the simple scientific reality.

Read this http://cimss.ssec.wisc.edu/wxwise/class/contrail.html Note this comment:
How long a contrail remains intact, depends on the humidity structure and winds of the upper troposphere.
Quite simply conditions at the weekend were conducive to long lasting contrails. In the video one aircraft is flying in an area conducive to long lasting contrails the other wasn't.

If the guy with the camera had zoomed in on the aircraft concerned he might have been able to see the airline logo. It's easily done with modern digital cameras. Chemtrails are pure fantasy. Simple as that.

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Post by Whisky Tango »

kendoyle wrote:I did find this paper linked to below. It states that for persistant contrails to occur a RHi of 100% isr equired and contrails that disappear in seconds are formed in dry conditions.So,again we have a video that appears to suggest that both a dry atmosphere and and atmpshere of 100% humidy are coexisting in much the same part of the sky...



Even if there were some distiance I doubt the humdity contrast was such to create the contrast in trails we see here.


Again, go read up on meteorology and stop wasting your (and our) time on chemtrails.... :roll: Try get hold of a Junior Cert geography book, it'll put all those perceptions you have to bed. Here's a good site

http://www.theweatherprediction.com/kid ... louds.html

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Post by ifty »

kendoyle wrote:I did find this paper linked to below. It states that for persistant contrails to occur a RHi of 100% isr equired and contrails that disappear in seconds are formed in dry conditions.So,again we have a video that appears to suggest that both a dry atmosphere and and atmpshere of 100% humidy are coexisting in much the same part of the sky...
Even if there were some distiance I doubt the humdity contrast was such to create the contrast in trails we see here.


An inversion layer perhaps? As others have stated this is an aviation forum not some sort of x files thing, the reason the other thread descended into to a farce is because this whole thing IS a farce.
You pass this way but once, there is no such thing as normal. There is you and the rest, now and forever. Do as you damn well please or you could end up being a pot-bellied, hairless boring old fart.

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Post by Pilot »

I think it's obvious that Ken/Alan have not come here looking for an explination.

They have had this explained to them plently of times, and very patiently, by so many people here, yet he refuses to listen.

I think it's obvious that he's come here trying to push his own flawed conspiricy theory, hoping to get it an audience. He's not looking for an explination, but rather looking for a stage.

P

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Post by captain slow »

Pilot i agree 100% with your take on this.

In fact its getting very boring, very very boring, very very very boring, very very very very boring...............oops was i saying the same thing over and over and over and over?....sorry there i go again :oops: :roll:

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Post by Whisky Tango »

Still though, I'd be very interested to see what he thought he saw at this mystery Dublin airport. Maybe he saw a bowser loading some liquid into a plane......no, it wasn't AvGas, it was NervGas! :lol:

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Post by Bump »

Pilot, Capt Slow... my sentiments exactly.

Ken, if I thought I saw a leprechaun at the bottom of my garden I wouldn't spend my days pestering the folks on Alan Titchmarsh.com!

Come on, this is an aviation forum - perhaps there's another forum better suited to your questions out there somewhere. This is getting a little long in the tooth.

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