Why AM radio stations goes far away in the nigiht?
During the day I can listen only to local AM radio stations. During the night even radio from other countries.
Why?
Note.
I am asking about medium wave radio not short wave radio.
There are a couple of different layers of the ionosphere in play here. The lower layer, called the D layer, tends of absorb radio signals during the day. At night, the Sun is gone and the ionization of this layer ceases. The D layer disappears and signals can pass higher up to layers that refract, rather than absorb signals like the E or F layers.
During the day, MF sky wave prorogation is absorbed and you can only get signals via ground wave propagation. At night, you get the sky wave.