Why do long distance radio broadcasts use shortwave bands?

^ Answer explained in detail...

See, if a wave has a larger wavelength it gets attentuated.... imagine a wave large enough.....while travelling through air it absorbs a lot of noise( All the traffic noise which are sound waves ), the noise waves also are carried with wave which makes it unclear. eg: AM waves. If short waves are used it reduces noise absorption and give you crystal clear voice. This is the reason even stereo effect can be broadcasted over a long range through FM. ie: it gets attentuated