Disappearing Contrails
Gentleman Aviator
Without wishing to be a scaremonger, what about the dangers of the Dihydrogen Monoxide present in the contrails .......
Without wishing to be a scaremonger, what about the dangers of the Dihydrogen Monoxide present in the contrails
I think we should start a petition and get Tony Bliar to do one good thing during his reign and lobby the UN to get this evil compound banned.
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Melchett01 and teeteringhead - will you tell them or shall I? We dont want to increase the number of converts as theres not enough seats to go around these days it seems.
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The main by-product of combustion of hydro-carbon fuel is indeed water. As stated it is produced at the same quantity of hydro-carbon fuel combusted. In combustion of the fossil fuel the hydrogen component combines with oxygen to produce water, H2O. The carbon content of the fuel combines separately with oxygen molecules (O2) to produce CO2 as well.
Carbon Monoxide is also a by-product of petrol but not of diesel or, AFAIK, of kerosene. The different by-products are a result of the actual composition of each fuel. Petrol, and I guess some of the others, also combine with nitrogen to produce NxOs.
Carbon Monoxide is also a by-product of petrol but not of diesel or, AFAIK, of kerosene. The different by-products are a result of the actual composition of each fuel. Petrol, and I guess some of the others, also combine with nitrogen to produce NxOs.
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All this science has me baffled... I do remember a dit about contrails though?
Many years ago I was showing a bunch of elderly visitors around the Air Traffic Control Tower where I worked. I was explaining the local airspace, and pointed out the airways that surrounded us and explained what they were, when an old lady from the back chipped in with, "Oh yes, I see them marking them out with white smoke every morning"
Many years ago I was showing a bunch of elderly visitors around the Air Traffic Control Tower where I worked. I was explaining the local airspace, and pointed out the airways that surrounded us and explained what they were, when an old lady from the back chipped in with, "Oh yes, I see them marking them out with white smoke every morning"
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I was pleased to leave the old 15:1 well behind and carry on depleting the ozone layer. Flame speeds were always interesting though!
Years ago when the RAF had more aircraft able to reach contrailing level, 'contrail willies' were occasionally created. Errm, 'meat and 2 veg' floating across the sky - which could be seen for miles.....
Reportedly, someone from Leuchars did this - and the offending item floated serenely over Edinburgh one RAFVR weekend in the pre-Duncan Sandys days. Much to the consternation of the chief god-botherer of that fair city who phoned the station and complained.
"No problem",came the reply "we'll sort it out!".
So, a few minutes later, a whole gang of Meteors, Vampires or whatever clambered up to Flight Level nosebleed in line abreast, then charged through the offending item. A few complicated battle formation turns later, they came back through it again at 90 deg to their original track.....
So, if the general public hadn't noticed the willy before, an obviously scrawled out one certainly got their attention.
Harry-the-Staish did not quite see the funny side, I am led to believe!
Reportedly, someone from Leuchars did this - and the offending item floated serenely over Edinburgh one RAFVR weekend in the pre-Duncan Sandys days. Much to the consternation of the chief god-botherer of that fair city who phoned the station and complained.
"No problem",came the reply "we'll sort it out!".
So, a few minutes later, a whole gang of Meteors, Vampires or whatever clambered up to Flight Level nosebleed in line abreast, then charged through the offending item. A few complicated battle formation turns later, they came back through it again at 90 deg to their original track.....
So, if the general public hadn't noticed the willy before, an obviously scrawled out one certainly got their attention.
Harry-the-Staish did not quite see the funny side, I am led to believe!
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Trailing - the temp of -57c ?
I was interested to see Brian A's statement
Does not equate with this website info.
http://asd-www.larc.nasa.gov/GLOBE/r...n_teacher.html
Nice little chart/s.
Cheers
TG
Contrails will only occur when the outside air temperature around the aircraft is at or below -57 degrees Celsius.
http://asd-www.larc.nasa.gov/GLOBE/r...n_teacher.html
Nice little chart/s.
Cheers
TG
I don't own this space under my name. I should have leased it while I still could
I was interested to see Brian A's statement
Does not equate with this website info.
http://asd-www.larc.nasa.gov/GLOBE/r...n_teacher.html
Nice little chart/s.
Cheers
TG
Does not equate with this website info.
http://asd-www.larc.nasa.gov/GLOBE/r...n_teacher.html
Nice little chart/s.
Cheers
TG
I will dig the AP out Monday.
IIRC the Mintra level was based on the height at which a Spitfire would begin trailing
The MINTRA line that you get on the tephigrams was (is) indeed based on a Spit and was based on condensation with respect to ice. Although it uses a Spit it is still useful today because it represents the limiting temp above which contails are unlikely to be formed by anything. In practice that means you are unlikely to get contrails until the ambient temp is a few degrees lower than the MINTRA value given on the tephigrams.
Using a tephigram, if you draw 2 lines on it that are 11 and 14 deg C colder than the MINTRA critical temp (Tc) at any level and then plot a representative point at any level, then the chances of contrails are as follows:
T > (Tc-11) = contrails unlikely
(Tc-11)>T>(Tc-14) = short non-persistent contrails
T<(Tc-14) = long persistent contrails
Persistent trails are more likely with hight humidity and you are more likely to get them if you fly at/ around the same level as layers of cirriform clouds.
The link given above goes to the Appleman chart which is a graphical way of predicting contrails including the effects of relative humidity (RH). Four lines are the 4 lines show the Tc for jet ac at different values of RH. As long as the tem lies to the left of the O% RH, you will get contrails, but if it lies to the right of the 100% RH line, all things being equal you won't get anything.
And on that note, my head hurts, I'm having horrible horrible flashbacks and am off to lie down in a darkened room with a good stiff drink.
Class dismissed!
I don't own this space under my name. I should have leased it while I still could
Melchett, did you do all that off the top of your head?
If so, have an A-cat, or you're a met man in which case is it going to be fine at 1100 on Sunday?
If so, have an A-cat, or you're a met man in which case is it going to be fine at 1100 on Sunday?
PN
I am neither an A-Cat (fat chance!) nor a met man, although I do have some not inconsiderable experience of the meteorological variety from my time at uni.
It's amazing what rubbish you can dig out from the back of your mind from years before; now a days I struggle to remember what happened at the start of a film 90 minutes later, but I was sure I we had covered this sort of thing as part of the course. A bit of rummaging through my old notes later ... and hey presto.
Sorry if I have just ruined any impression of being an aeronautical genius that you may have had! As for Sunday, it should be ok if you're in the midlands - east of the country, bit cloudy up the west side of England, Wales and east Scotland and a bit rainy up over the west of Scotland (shock horror). Although I must put a Michael Fish sized caveat on that ...... it's dark and I can't see anything out of the window which is my preferred method of forecasting !
I am neither an A-Cat (fat chance!) nor a met man, although I do have some not inconsiderable experience of the meteorological variety from my time at uni.
It's amazing what rubbish you can dig out from the back of your mind from years before; now a days I struggle to remember what happened at the start of a film 90 minutes later, but I was sure I we had covered this sort of thing as part of the course. A bit of rummaging through my old notes later ... and hey presto.
Sorry if I have just ruined any impression of being an aeronautical genius that you may have had! As for Sunday, it should be ok if you're in the midlands - east of the country, bit cloudy up the west side of England, Wales and east Scotland and a bit rainy up over the west of Scotland (shock horror). Although I must put a Michael Fish sized caveat on that ...... it's dark and I can't see anything out of the window which is my preferred method of forecasting !
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Do tephigrams still have the mintra line on them? From what I understand this
is a hangover from the wartime when aircraft did not wish to make themselves too visible for obvious reasons.
is a hangover from the wartime when aircraft did not wish to make themselves too visible for obvious reasons.