Balcony Sight Baffles Me

Sometimes when I photograph the balconies at Grand Central Terminal, I see ordinary recognizable humans, like this photogenic woman having some fun letting her hair down.

But other times I photograph what looks like very strange things on the Grand Central balconies. Below is an example from December 17, 2015.  In the midst of some weird blackness above the balcony border, we see three strange blobs -- one yellow, one green, and one purple. Are they the faces of some strange paranormal things?