If you read the scifi.se Q&A I linked to, which mentions several contradictory answers given by Gibson over the years, you'll see it's not so simple and definit

If you read the scifi.se Q&A I linked to, which mentions several contradictory answers given by Gibson over the years, you'll see it's not so simple and definitely not overthinking it! Analog TVs didn't always give static snow, by the way. One of Gibson's latest answers is a retweet of Monica Lewinsky's (yes, that Monica) photo of a cloudy gray day and stating "that's exactly what I was thinking of". It looks nothing at all like an analog's TV static snow!