Trailspotter
Senior Member.
Today I have observed an unusual type of contrail evolution that I have not encountered before. There [seemed to be] an asymmetric contrail behind a four-engine jet: three trails has merged together, whereas one stayed apart:
![P1170293.JPG P1170293.JPG](https://www.metabunk.org/data/attachments/0/808-947e7baa83b6aa1c0a52fef5ddefa013.jpg)
The triple trail has dissipated quickly via Crow instability, whereas the single trail has persisted and spread a bit (in a limited area of the sky):
![P1170294.JPG P1170294.JPG](https://www.metabunk.org/data/attachments/0/812-a92ccd6c935e48c9444667ad7c49f72b.jpg)
![P1170295.JPG P1170295.JPG](https://www.metabunk.org/data/attachments/0/807-a6e2fc459a76705c178f5f146095a940.jpg)
![P1170296.JPG P1170296.JPG](https://www.metabunk.org/data/attachments/0/806-b5d28b08f1f832ccc15f49ec09e352b6.jpg)
![P1170297.JPG P1170297.JPG](https://www.metabunk.org/data/attachments/0/805-f0256bf3636c2ba577d2d2d2df4c9cc6.jpg)
Actually, I've observed this type of contrail evolution twice on the two consecutive planes flying by the same route with a few minutes interval, but recorded only the second one. The planes left two parallel segments of persistent trails ending at about the same distance:
![P1170300.JPG P1170300.JPG](https://www.metabunk.org/data/attachments/0/809-0fd9be08c230a3e584256415e489febf.jpg)
In contrast, another four-engine jet some twenty minutes later has left a symmetric contrail that quickly dissipated, again via Crow instability:
![P1170316.JPG P1170316.JPG](https://www.metabunk.org/data/attachments/0/804-75a5d1c2f6ce40923641dbae45588a4a.jpg)
![P1170317.JPG P1170317.JPG](https://www.metabunk.org/data/attachments/0/803-2ef595db07c853a2120a1042f499ad88.jpg)
![P1170319.JPG P1170319.JPG](https://www.metabunk.org/data/attachments/0/802-ae67090be89099a7ff591dba329eccbb.jpg)
I have seen asymmetric trails behind four-engine planes before, but they either dissipated, or persisted all together. It is the first time I see the trail from one of the engines persisting, while the trails from the other engines dissipating.
What would be the likely origins of such asymmetric trails? I can hazard a guess, but would like to hear the expert opinion first.
![P1170293.JPG P1170293.JPG](https://www.metabunk.org/data/attachments/0/808-947e7baa83b6aa1c0a52fef5ddefa013.jpg)
The triple trail has dissipated quickly via Crow instability, whereas the single trail has persisted and spread a bit (in a limited area of the sky):
![P1170294.JPG P1170294.JPG](https://www.metabunk.org/data/attachments/0/812-a92ccd6c935e48c9444667ad7c49f72b.jpg)
![P1170295.JPG P1170295.JPG](https://www.metabunk.org/data/attachments/0/807-a6e2fc459a76705c178f5f146095a940.jpg)
![P1170296.JPG P1170296.JPG](https://www.metabunk.org/data/attachments/0/806-b5d28b08f1f832ccc15f49ec09e352b6.jpg)
![P1170297.JPG P1170297.JPG](https://www.metabunk.org/data/attachments/0/805-f0256bf3636c2ba577d2d2d2df4c9cc6.jpg)
Actually, I've observed this type of contrail evolution twice on the two consecutive planes flying by the same route with a few minutes interval, but recorded only the second one. The planes left two parallel segments of persistent trails ending at about the same distance:
![P1170300.JPG P1170300.JPG](https://www.metabunk.org/data/attachments/0/809-0fd9be08c230a3e584256415e489febf.jpg)
In contrast, another four-engine jet some twenty minutes later has left a symmetric contrail that quickly dissipated, again via Crow instability:
![P1170316.JPG P1170316.JPG](https://www.metabunk.org/data/attachments/0/804-75a5d1c2f6ce40923641dbae45588a4a.jpg)
![P1170317.JPG P1170317.JPG](https://www.metabunk.org/data/attachments/0/803-2ef595db07c853a2120a1042f499ad88.jpg)
![P1170319.JPG P1170319.JPG](https://www.metabunk.org/data/attachments/0/802-ae67090be89099a7ff591dba329eccbb.jpg)
I have seen asymmetric trails behind four-engine planes before, but they either dissipated, or persisted all together. It is the first time I see the trail from one of the engines persisting, while the trails from the other engines dissipating.
What would be the likely origins of such asymmetric trails? I can hazard a guess, but would like to hear the expert opinion first.
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