| has gloss | eng: Sporadic E or Es is an unusual form of radio propagation using characteristics of the Earths ionosphere. Whereas most forms of skywave propagation use the normal and cyclic ionization properties of the ionospheres F region to refract (or "bend") radio signals back toward the Earth's surface, sporadic E propagation bounces signals off smaller "clouds" of unusually ionized atmospheric gas in the lower E region (located at altitudes of approx. 90 to 160 km). This occasionally allows for long-distance communication at VHF frequencies not usually well-suited to such communication. |