OH what a coincidence !!!
The AM and short wave radio stations also have a much better signal
starting in the evening til the morning. The reason for this phenomenon
is the reflecting
ionosphere! Another coincidence!
LW (153kHz - 279kHz)
AM (531kHz - 1611kHz)
This correlates even somehow to the Morgans VHF claims.
Especially in the autumn time you can get VHF over-wide-ranges,
any ham and amateur-radio person can tell you this.
The AM ground wave is direct, the space-wave is ionosphere reflected.
The main reflection effect the ionosphere has is from 500kHz - 50 MHz.
Longwave from 50kHz - 200kHz is little affected by the ionosphere
and has therefore little field-strenth-difference day VS. night-time.