The region of the earth's atmosphere between the stratosphereand the exosphere, consisting of several ionized layers andextending from about 50 to 250 miles (80 to 400 km) above thesurface of the earth.
Magnetosphere Ionoshpere Exosphere (upper and lower) Thermosphere Homosphere - Mesosphere - Stratosphere - Troposphere (high, low, medium, planetary boundary)
It depends on the wavelength. Some travel further during the day and others at night. It mostly has to do with the presence or absence of the sun and the ionosphere. At night the characteristics of the ionoshpere help bounce shorter wavelengths, like those of AM radio and short-wave radio bands, and some can even circle the Earth.
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