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 extent 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.
Its existence was predicted in 1902 independently and almost simultaneously by the American electrical engineer Arthur Edwin Kennelly (1861-1939) and the British physicist Oliver Heaviside (1850-1925). However, it was not until 1924 that its existence was detected by Edward V. Appleton.
In 1899, Nikola Tesla, in his Colorado Springs experiments, transmitted extremely low frequency electromagnetic waves between the earth and ionosphere, up to the Kennelly-Heaviside layer (Grotz, 1997). Tesla made mathematical calculations and computations based on his experiments. He predicted the resonance frequency of this area within 15% of modern accepted experimental value. (Corum, 1986) In the 1950s, researchers confirmed the resonance frequency was at the low range 6.8 Hz.
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. In the musical, one cat is chosen each year by Old Deuteronomy to go to the Heaviside Layer and begin a new life. In the song "The Journey to the Heaviside Layer", it is stated that the Heaviside Layer is "past the Russell Hotel" and "past the Jellicle moon", indicating that it is very far away and difficult to access.
In the end of the musical, Grizabella is chosen to go the Heaviside Layer. She does so by ascending on a flying tyre until she reaches a structure resembling clouds, into which she disappears.
The "Heaviside Layer" is another name for the Ionosphere. There are two kinds of ions, anions and cations. This reference may be a scientific pun by T. S. Eliot.