Nobody Built This "Snowman"

Photo date: July 2, 2015. Photographer: Mark Mahin.

If I were to show you the photo below without mentioning the date it was taken, and ask you to explain, I can imagine what you would say. You would tell me that strangely enough, this shows a snowman on top of a roof. You would probably cite the "falling snow" as a kind of corroboration of this explanation.

The problem with that explanation is that the photo was taken in New York City on July 2 (where it's way too warm for snow or snowmen in July). The "snowman" does not appear in other photos I have of this building taken about the same time.

There was no fog, mist, rain, or precipitation on this night. The air quality as listed on airnow.gov was good, with a rating of 46 (anything below 50 is considered good).  The pollen level listed on  pollen.com was low to medium, with a rating of 4.7.