My projects have always done all-sky measurements under all conditions because I'm concerned with the effects on wildlife, as well as interested in seeing the stars. For example, this paper --> iopscience.iop.org/article/10.1... where we show the influence of the % clouds on illuminance.

"(...) Recent reports, however, suggest that urban insects are evolving reduced flight-to-light behaviour. If spiders continue to prioritize light over prey, artificial light could therefore become an ecological trap for spiders if fewer insects approach the light."

From the abstract: "Outdoors, this likely draws them to prey-dense, artificially lit areas. (...)"

Very interesting observation, indeed! I had not paid attention to this phenomenon... I will try to detect it here (we have a generous supply of clouds all year round ;)

I'm used to the usual effect of clouds (reflection of light pollution, darkening of the natural sky), but it's interesting to see the zenith being darker than "normal" once the sky overhead cleared but Montreal was still covered, and that the zenith became brighter once the sky cleared over Montreal

This reminds me of a very interesting observation a couple in 2022:
While taking SQC measurements from a park in Montreal's suburbs, I noticed that the zenith became darker just after the clouds cleared overhead but were still covering Montreal (2nd image). The clouds acted like a blanket over MTL