Explain This!!!!

A group of us are going into the board meeting last night.  I'm trailing behind because I'm old  and I'm gimpy which makes me slow.  Of course I'm looking around! ( Habit from living out so much growing up.)  I see this and manage to get this one clear picture.  (Naturally I  had a point and shoot in my purse.)

I see the contrails but what is this one.  It is definitely heavier than the clouds.  I didn't stay to watch it. I was already a tad late to the meeting.

Explanations please!