Sporadic-E Propagation:

At certain radio-frequencies, the ionospheric E layer seldom returns signals to the Earth. This consequence is irregular, and circumstances can change quickly. For this reason, it is termed as sporadic-E propagation. It is most probable to take place at frequencies among around 20 and 150 MHz. Occasionally it is noticed at frequencies as high as 200 MHz. The propagation variety is on the sort of some hundred kilometers, though occasionally communication is noticed over distances of 1,000 to 2,000 km (i.e., 600 to 1,200 mi).

The standard FM broadcast band is at times affected by sporadic-E propagation. The similar is true of the lowest television (TV) broadcast channels, particularly channels 2 & 3. Sporadic-E propagation is at times incorrect for effects which occur in the lower environment separately of the ionosphere.