Photo date: September 23, 2016. Photographer: Mark Mahin.
The photo below shows some purple orbs and bright white orbs above a building in New York City. Note the "vertical bias" (something I frequently see, as shown in this series). We only see orbs above the buildings, which is not the random photo positions we would see if natural particles near the camera were the cause.
here for other examples).
There was no fog, mist, rain or precipitation when I was photographing on this night.