UFO Seen From Airplane: Strange Structure Hovering in the Clouds

• When: February 16th, 2017
• Where: Seen during airplane flight over Europe
• What: Strange structure hovering in cloud; Possibly identified as plumes from power plant below
  

A passenger on a flight headed from Warsaw to London saw something very strange outside the window, several dark tube-shaped objects hovering in the clouds. They sent photo and testimony to MUFON (case 82114).

https://www.mufoncms.com/files_jeud8334j/82114_submitter_file3__IMG0351.JPG

https://www.mufoncms.com/files_jeud8334j/82114_submitter_file5__IMG0353.PNG

Flying from Warsaw to London Heathrow, looking out the window to my left.
Out of the corner of my eyes I saw these dark, thin figures in the middle of a cloud.
It definitely wasn't a building because we were too high up so I thought they were mini tornadoes
There were 4 figures: 2 tall ones and 2 slightly small ones. They were very close together and they weren't moving at all. They were dark, had a thicker upper body and a thinner lower body. One of them looks like they had wings.
I was in awe and shocked at how it was all deserted then there were these random weird objects just standing on top of a cloud. I took photos and showed my parents and brother the photo and they couldn't believe their eyes. I was also a little bit excited because I have never seen anything like this before.
Flew past the object(s) then it disappeared.

What do you think this airplane passenger witnessed and photographed? Could this be a natural phenomenon? Share your theory about this UFO sighting in the comments or on Twitter or Facebook!