Contrails...or not?

[kr0ne]

Did further research show Glamdring's suggested explanation in post 2 to be incorrect?

[SadToes]

I am not a wearer of the tin foil hat BUT

I have alway watched the skies and when i was younger contrails did what they should do as they are water vapour, what they did was disapear shortly after but some of the ones of today dont and can completly block the sky and sun. i have watched it

[grahamwilman01]

I am not a wearer of the tin foil hat BUT

I have alway watched the skies and when i was younger contrails did what they should do as they are water vapour, what they did was disapear shortly after but some of the ones of today dont and can completly block the sky and sun. i have watched it

the tinfoil ain't working anymore

[grahamwilman01]

Let me put it in easy terms for simpletons to understand, you know when you start your car on a very cold morning and you get the hot gas from the engine hitting the cold air you get what looks like steam, it is known as condensation that is exactly what happens at 30000 ft where temperatures can get as low as minus twenty seven it is the hot exhaust from the aircraft hitting the cold air not some evil government project to turns us into retarded mutants conspiracy theories are like sh1tholes everyone has one

Exactly.Well then,why doesn't it happen all the time?(which was my original question).How come sometimes contrails form,and sometimes not?Surely it can't get too warm up there

it only happens above 27000 feet doing my own research into this daft conspiracy theory it depends on temperature and humidity conditions at altitude that form the contrails

[kr0ne]

I am not a wearer of the tin foil hat BUT

Maybe it would help? Would keep the sun off your head at least...

[SadToes]

Sure....... because the government would never lie to us would they?

Jeez... try thinkining out of the box sometimes

[cottonfoo]

Personally I'd just try thinking

But seriously, no.

[grahamwilman01]

Sure....... because the government would never lie to us would they?

Jeez... try thinkining out of the box sometimes

booooooooooored

yes and Father Christmas and the tooth fairy exist

[bigbassman]

Did further research show Glamdring's suggested explanation in post 2 to be incorrect?

It made sense to me.Unfortunately I think I used the wrong wording in my heading.When I wrote "Contrails..or not" I didn't mean 'are they contrails or are they not?' Unfortunately the content has wandered WAY off course. Honestly,I just wanted to know why some days there are lots of trails (see what I did there?) and some days there are none at all.

[ChrisCSL]

It's to do with the 'dewpoint'. The relationship between moisture and temperature. Don't forget that any moisture sucked into the front of the engine doesn't disppear - it just gets blown out of the back much hotter.

'Dewpoint' is the point below where moisture ceases to exist as an invisible 'gas', and condenses out into water droplets. So - at sea level - wet air on a hot day is 'muggy' but wet air on a cold day is fog.

As an aircraft climbs, it will reach an altitude where the air is cool enough to fall below the dewpoint. This is why if you see an aircraft climbing it will start to make a contrail. This altitude varies according to the air temperature and its moisture content. In hot dry weather you will see aircraft flying very high with either no contrail, or a very short-lived one, but in cold weather the dewpoint altitude will be much lower, so you get the opposite.

For the same reason, it's better to photograph steam engines in freezing weather than on hot summer days.

[kr0ne]

try thinkining out of the box sometimes

What does this mean, exactly? I hear it a lot at work but nobody who says it seems to have any idea...

[kr0ne]

It made sense to me.Unfortunately I think I used the wrong wording in my heading.When I wrote "Contrails..or not" I didn't mean 'are they contrails or are they not?' Unfortunately the content has wandered WAY off course. Honestly,I just wanted to know why some days there are lots of trails (see what I did there?) and some days there are none at all.

Yeah, I know you weren't asking loony tunes questions...

Glamdring suggested an explanation as to why they do not always appear in post 2 though and grahamwilman01 says that he has now also read a little about the subject and came to a similar conclusion.

[kr0ne]

It's to do with the 'dewpoint'. The relationship between moisture and temperature. Don't forget that any moisture sucked into the front of the engine doesn't disppear - it just gets blown out of the back much hotter.

'Dewpoint' is the point below where moisture ceases to exist as an invisible 'gas', and condenses out into water droplets. So - at sea level - wet air on a hot day is 'muggy' but wet air on a cold day is fog.

As an aircraft climbs, it will reach an altitude where the air is cool enough to fall below the dewpoint. This is why if you see an aircraft climbing it will start to make a contrail. This altitude varies according to the air temperature and its moisture content. In hot dry weather you will see aircraft flying very high with either no contrail, or a very short-lived one, but in cold weather the dewpoint altitude will be much lower, so you get the opposite.

For the same reason, it's better to photograph steam engines in freezing weather than on hot summer days.

Excellent reply!

[ChrisCSL]

Thankee.

Also, don't forget that at high altitude, the water droplets will in fact be ice crystals, which makes for a very impressive contrail.

I live under a transatlantic air lane, and some mornings in mid-winter you can see aircraft flying among several earlier contrails. It's beautiful at dawn.

During the war, one of the jobs of the tail-gunner on bombers was to warn the pilot when he was generating a contrail. The German fighters might not have been able to spot a black Lancaster, but all he had to do was follow a moonlit contrail and ..... endgame.

[bigbassman]

It's to do with the 'dewpoint'. The relationship between moisture and temperature. Don't forget that any moisture sucked into the front of the engine doesn't disppear - it just gets blown out of the back much hotter.

'Dewpoint' is the point below where moisture ceases to exist as an invisible 'gas', and condenses out into water droplets. So - at sea level - wet air on a hot day is 'muggy' but wet air on a cold day is fog.

As an aircraft climbs, it will reach an altitude where the air is cool enough to fall below the dewpoint. This is why if you see an aircraft climbing it will start to make a contrail. This altitude varies according to the air temperature and its moisture content. In hot dry weather you will see aircraft flying very high with either no contrail, or a very short-lived one, but in cold weather the dewpoint altitude will be much lower, so you get the opposite.

For the same reason, it's better to photograph steam engines in freezing weather than on hot summer days.

That about does it for me Chris.Explained in a nutshell.I had wondered about the short trails as well.Thanx a lot.