How does this handle situations where you haven't got 'line of sight' (or rather, an unobstructed path) to the transmitter (e.g. when you're nestled in between some mountains)?
One of my favorite activities in the summer is to go get lost in the Cascades, and when the sun goes down, settle in to a hammock with a little multi-band radio to see what I can pick up. As the evening wears on, I can typically start to receive FM radio stations in Canada several hundred kilometers away. Once the sun has risen again, I can no longer tune those stations no matter how much I fiddle with antenna orientation. NOAA weather bands also become easier to tune clearly at night.
As to why VHF frequencies seem to propagate better at night, I could only speculate, but they do seem to—at least on occasion.
Also came across this interesting page: https://www.fcc.gov/media/radio/am-stations-at-night