Propagation & spaceweather

Solar cycle  25 

Where the above map indicates the foF2 NVIS Critical Frequency, the relationship between the foF2 frequency and the Maximum Usable Frequency (MUF) is approximately 1:3. Multiplying the foF2 critical frequency by 3 approximates the MUF. The following color chart is adjusted to indicate the MUF.

MISSING MUF_colors.png