"The following factors affect the range of HF communication:
1. Transmitter power
3. Time of the day
6. Disturbance of the ionosphere"
Why is it the lower the frequency the further they travel, is are am i right here?
'Location'? would that be to do with the ionospheres lengths being different i.e. getting smaller towards the poles?
As with 'disturbance of the ionosphere' i take it the following wiki abstract is what they it is referring to;
"A sudden ionospheric disturbance (SID) is an abnormally high ionization/plasma density in the D region of the ionosphere caused by a solar flare. The SID results in a sudden increase in radio-wave absorption that is most severe in the upper medium frequency (MF) and lower high frequency (HF) ranges, and as a result often interrupts or interferes with telecommunications systems."
From that i don't understand why an increase causes it to absorb the radio wave? as i thought it was this increase in the ions that created the D region, which enabled radio waves or sky waves to reflect from