Nightly DX 130-150 miles?

[Dan4328]

When I got a normal FM only radio as a gift some time ago, I didn't know you could have a wire antenna for FM. So I played around with it and found out if a signal was coming from the north I wanted to go completely perpendicular (I think that's it) to it so the antenna would be facing east/west, and allowed me to pick up WNOX from Knoxville every night, and if I make the antenna go North/South, it'll pick up stations from Huntsville that aren't even on the FM list such as Lite 96.9 and 99.1 and sometimes 95.9. How is this possible with a normal radio that doesn't have that good of a filter (Stations leaking onto other frequencies from like 94.3 to 94.5) to pick these up every night which end up dying out around 8:30 AM?

[GroundUrMast]

The upper layers of the atmosphere can reflect radio waves. The weather and solar radiation effect the atmosphere's ability to reflect radio waves, so the effect is quite variable. However, as the sun goes down, it's common to observe a significant change in radio wave propagation, thus the fairly common 'nightly skip event'. ('Skip' as in radio waves skipping off of charged layers of the atmosphere.)