aileron11
Posts: 167
Joined: Wed Oct 19, 2005 5:46 am

I Have Question About Contrails.

Mon Dec 11, 2006 10:01 am

I checked to see if this has been discussed before but did not find anything, so my question is, why does some airplanes have contrails that look like they skip, just today I saw three airplanes flying and instead of seeing long continues line I saw the contrail stop and then start again I looked as long as I could see the airplane and it kept happening. Just wondering if any else seen this or maybe even have an answer thanks.
Jersey Lou
 
steeler83
Posts: 7391
Joined: Sat Feb 25, 2006 2:06 pm

RE: I Have Question About Contrails.

Mon Dec 11, 2006 10:16 am

It has to do with atmospheric conditions aloft. There must be some little isolated pockets of very dry air aloft for this phenomenon to occur. With more humidity at F.L. 20-something-000 feet, the water vapor discharged from the jets will condense into clouds, or what we see as contrails. If the air is very dry aloft, the vapor cannot condense and crystalize. Therefore no contrail is seen.

Please somebody correct me if I am wrong! I read about contrails in "The National Audaban Society Field Guide to North American Weather. (I don't think Audaban is spelled right btw.) Anyway, that is my source. Did I misinterpret or misread something? Please tell me!!
Do not bring stranger girt into your room. The stranger girt is dangerous, it will hurt your life.
 
We're Nuts
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RE: I Have Question About Contrails.

Mon Dec 11, 2006 10:25 am

It's because they are spraying chemicals as part of a top secret government program.  shhh 
Dear moderators: No.
 
aileron11
Posts: 167
Joined: Wed Oct 19, 2005 5:46 am

RE: I Have Question About Contrails.

Mon Dec 11, 2006 10:36 am

Quoting Steeler83 (Reply 1):
It has to do with atmospheric conditions aloft. There must be some little isolated pockets of very dry air aloft for this phenomenon to occur. With more humidity at F.L. 20-something-000 feet, the water vapor discharged from the jets will condense into clouds, or what we see as contrails. If the air is very dry aloft, the vapor cannot condense and crystalize. Therefore no contrail is seen.

Please somebody correct me if I am wrong! I read about contrails in "The National Audaban Society Field Guide to North American Weather. (I don't think Audaban is spelled right btw.) Anyway, that is my source. Did I misinterpret or misread something? Please tell me!!

Thanks for the info.

Quoting We're Nuts (Reply 2):
It's because they are spraying chemicals as part of a top secret government program.

i had feeling something like that was happening.
Jersey Lou
 
steeler83
Posts: 7391
Joined: Sat Feb 25, 2006 2:06 pm

RE: I Have Question About Contrails.

Mon Dec 11, 2006 10:41 am

Quoting Aileron11 (Reply 3):
Thanks for the info.

Anytime. Although, I must say that I don't know how accurate that is. I did have a supreme interest in meteorology, but of course, that interest has shifted towards geography and planning.

Quoting Aileron11 (Reply 3):
Quoting We're Nuts (Reply 2):
It's because they are spraying chemicals as part of a top secret government program.

i had feeling something like that was happening.

Heheh, yeah this is true as well Big grin

I think that the increasing number of really bad drivers has something to do with this, and one royally bad driver practically ran my girlfriend and myself off the road just last night! If he could've gotten any closer to my girlfriend's trunk, he would've been in it...
Do not bring stranger girt into your room. The stranger girt is dangerous, it will hurt your life.
 
Vref5
Posts: 187
Joined: Tue Dec 13, 2005 2:55 pm

RE: I Have Question About Contrails.

Mon Dec 11, 2006 10:50 am

Quoting We're Nuts (Reply 2):
It's because they are spraying chemicals as part of a top secret government program. shhh

Hahaha Big grin

Ahh, yes, the good ol' chemtrails.  Silly

Quoting Steeler83 (Reply 1):
It has to do with atmospheric conditions aloft. There must be some little isolated pockets of very dry air aloft for this phenomenon to occur. With more humidity at F.L. 20-something-000 feet, the water vapor discharged from the jets will condense into clouds, or what we see as contrails. If the air is very dry aloft, the vapor cannot condense and crystalize. Therefore no contrail is seen.

You've got the rough idea, though there are actually two things that matters here:

1. Low temperature

AND

2. Vapor pressure

It's pretty cold up there every day, but not always the vapor pressure needed. That's why you don't always see contrails.

Basically, if you have sufficient vapor pressure, it will form a "cloud"... and if you don't, it won't. There, that's a bit of my aviation meteorological training put to some use. Big grin
 
graphic
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Joined: Sat Nov 18, 2006 10:41 am

RE: I Have Question About Contrails.

Mon Dec 11, 2006 10:56 am

There needs to not only be enough water vapor (not as much as you'd think because jet engines themselves produce a large amount of water vaport), but there also needs to be sufficient nuclei for the vapor to condense on (microscopic dust, smoke particles). When the temperature is so cold that the air cannot hold the water vapor the engines produce, it will condense on the nuclei and a cloud will be visible.
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steeler83
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RE: I Have Question About Contrails.

Mon Dec 11, 2006 11:06 am

Quoting Vref5 (Reply 5):

Thank you very much  Smile

Naturally I should've known about cold temperature, OF COURSE!!! Vapor pressure I didn't even think of! THANKS!!!

Quoting Vref5 (Reply 5):
Basically, if you have sufficient vapor pressure, it will form a "cloud"... and if you don't, it won't. There, that's a bit of my aviation meteorological training put to some use.

And good training put to good use at that!  Smile
Do not bring stranger girt into your room. The stranger girt is dangerous, it will hurt your life.
 
bimmerkid19
Posts: 284
Joined: Wed Dec 06, 2006 4:43 pm

RE: I Have Question About Contrails.

Mon Dec 11, 2006 11:36 am

Quoting Vref5 (Reply 5):

...and trails of the bluejuice  Wink
Last flights: LH 3738 MUC - ZRH , LH 3749 ZRH - MUC . Upcoming: EK 50 MUC - DXB 3-aug. and EK 322 DXB - ICN 7- Aug.
 
steeler83
Posts: 7391
Joined: Sat Feb 25, 2006 2:06 pm

RE: I Have Question About Contrails.

Mon Dec 11, 2006 12:15 pm

Quoting Bimmerkid19 (Reply 8):
and trails of the bluejuice

what about the WN kool-aid?  Wink
Do not bring stranger girt into your room. The stranger girt is dangerous, it will hurt your life.
 
Pihero
Posts: 4196
Joined: Mon Jan 31, 2005 5:11 am

RE: I Have Question About Contrails.

Mon Dec 11, 2006 6:59 pm

Quoting Steeler83 (Reply 1):
It has to do with atmospheric conditions aloft. There must be some little isolated pockets of very dry air aloft for this phenomenon to occur.



Quoting Vref5 (Reply 5):
Basically, if you have sufficient vapor pressure, it will form a "cloud"... and if you don't, it won't.

All true, but if you both go just a bit further, it is a sure sign of clear air turbulence be it due to a wave or some drastic convective movements of the air mass.

Regards
Contrail designer

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