When sunspot activity increases, the reflecting capabilities of the F1 layer surrounding earth enable high frequency short-wave communications.
During the daytime when sunspot activity is at a maximum, the F2 layer can become intensely ionized due to radiation from the sun.
Outside a solar maximum it can still occur somewhat regularly within about 15 to 20 degrees from the geomagnetic equator, with the peak generally being in spring time.
During a solar maximum, television, amateur radio signals, private land mobile, and other services in the 30-60 MHz VHF spectrum are also propagated over considerable distances.
Television pictures propagated via F2 tend to suffer from characteristic ghosting and smearing, although they are mostly stronger and more stable than double hop Sporadic E signal.