1. 20 The distinct difference between the numerical results and the experimental one at higher altitudes is due to anomalous heating of the F layer ionosphere.

2. In the ionospheric F-layer the electron densityn increases with the formulan=a. cosχ+b in the morning (χ is meaning the zenithangle of the sun).

3. When this happens, MF radio waves can easily be received hundreds or even thousands of miles away as the signal will be refracted by the remaining F layer.