Thought this was interesting, I'll have to wait for the next snowfall to check it out. https://blogs.scientificamerican.com/illusion-chasers/a-snowy-illusion-for-the-holidays/
Notice that as the blinds occupy more area on the screen, the speed of the snowfall seems to accelerate. A great illusion to ponder during our white holiday season.
Nobody knows how Atarashi’s effect works, but our working hypothesis is that each time the snow disappears behind a blind, or reappears below it, it triggers transient increases in the activity of your visual system’s motion-sensitive neurons.
Such transient surges in neural activity are perhaps misinterpreted by your brain as faster motion speed.