Evening sky (again)

I presume the skies have always been this interesting and I just haven't noticed before, but each evening as I leave work there is "stuff" to look at.  This evening, most of the sky was dark, thick clouds, but just a clear area on the western horizon, allowing the sunset colours to shine through.

There was a rather nice red streak, but I couldn't stop the car, and by the time I found a place to park, it had gone - presumably a con trail.