F2 Propagation (F2-skip)
The F2 layer is found about 200 miles (320 km) above the Earth's surface and can reflect radio waves back toward the Earth. When the layer is particularly strong during periods of high sunspot activity, FM and TV reception can take place over 2000 miles (3000 km) or more, as the signal effectively "bounces" off the high atmospheric layer.
Read more about this topic: TV And FM DX