Air pollution

What you don't want to see in the bright blue sky when you walk out your backdoor on a Saturday morning:

Doctor my eyes, indeed.

Following a promotion to the Starfleet institute, Dr. Emmett Brown stalled out the reactors of the USS Enterprise, subsequently slowing it to 88 miles per hour.  Having achieved this state of near-suspended animation, he found himself, along with Lt. Jameson Trevor Kirk, Dr. Leonard MacAodha, over the skies of Glasgow, having just boarded the new flight engineer, Colin Montgomery Scott.  Soon after this image was taken - eager to return to the 22nd century - Lt. Kirk urged 1st Engineer Scott to quickly add altitude to access favorable winds. "Lieutenant, I'm giving her all we've got - she's gonna blow!" was the response. - a possible explanation for the picture.

h/t: qdub