Medium Waves

Medium Waves 

radio waves with wavelengths ⋋ between 10² and 10³ m (frequencies from 3 megahertz to 300 kilohertz). During daylight hours, medium waves are usually strongly absorbed by the ionosphere and propagate only as surface waves that follow the curvature of the earth’s surface. At night, they propagate like short waves, traveling great distances and undergoing reflection many times at the E layer of the ionosphere and the surface of the earth. Medium-wave radio transmission extends approximately 500–1,000 km during the day; at night, assuming reflection off the ionosphere, the corresponding figure is several thousand kilometers. Medium waves are used in radio broadcasting and radio navigation.