Kennelly-Heaviside Layer
The Kennelly-Heaviside Layer is also known as the E region or just as Heaviside Layer (after Oliver Heaviside). It is a layer of ionised gas occurring at 90-150km in altitude, one of several layers in the ionosphere. It reflects medium-frequency radio waves, and because of this reflection radio waves can be propagated beyond the horizon.
Propagation is affected by time of day. During the daytime the solar wind presses this layer closer to the Earth, thereby limiting how far it can reflect radio waves. On the night side of the Earth, the solar wind drags the ionosphere further away, thereby greatly increasing the range which radio waves can travel by reflection, called skywave. The extend of the effect is further influenced by the season (because of the differing distance between Earth and the Sun), and the amount of sunspot activity.
History
Nikola Tesla originally discovered this area (around July 3, 1899). He made mathematical calculations based off his experiments in his research of electromagnetic propagation and resonance and deduced that the resonant frequency of this area was approximately eight hertz. The Kennelly-Heaviside Layer was confirmed in 1923. In the 1950s, researchers confirmed the resonant frequency was approximately eight hertz.
Its existence was proposed in 1902, independently, and almost simultaneously by the American electrical engineer Arthur Edwin Kennelly (1861-1949) and the British physicist Oliver Heaviside (1850-1925).
Cultural impact
The "Heaviside Layer" is used as a symbol for heaven (in the afterlife sense) in Andrew Lloyd Webber's musical Cats. This reference is based on a quote found in a letter written by T. S. Eliot, whose book Old Possum's Book of Practical Cats forms the basis of the musical.
See also
