Whistler (radio)

Whistler (radio)

A Whistler is a very low frequency electromagnetic (radio) wave generated by lightning. Frequencies of whistlers are 1 to 30 kHz, with maximum usually at 3 to 5 kHz. Although they are electromagnetic waves, they occur at audio frequencies, and can be converted to audio using a suitable receiver. They are produced by lightning strikes (mostly intracloud and return-path) where the impulse travels away from the earth and returns to the earth traveling along magnetic field lines. They undergo dispersion of several thousand kHz due to the slower velocity of the lower frequencies through the plasma environments of the ionosphere and magnetosphere. Thus they are perceived as a descending tone which can last for a few seconds. The study of whistlers allows categorization into Pure Note Whistlers, Diffuse, 2-hop, and Echo Train types.

In addition, they have been received from Jupiter showing the presence of lightning there.

Nomenclature

The propagation of a signal in the earth-ionosphere wave guide is known as a sferic. If the signal is injected through the ionosphere and allowed to propagate through the magnetosphere, the signal is now prone to a bounce-mode propagation, reflecting back and forth on opposite sides of the planet until totally attenuated. To clarify which part of this hop pattern the signal is in, it is specified by a number, indicating the portion of the bounce path it is currently onR.L. Smith and J.J. Angerami. "Magnetospheric Properties Deduced from OGO 1 Observations of Ducted and Nonducted Whistlers." Journal of Geophysical Research, vol 73, no 1. January 1, 1968.] . On its first upward path, it is known as a 0+. After passing the geomagnetic equator, it is referred to as a 1-. The + or - sign indicates either upward, or downward, propagation, respectively. The numeral represents the half-bounce currently in progress. The reflected signal is redesignated 1+, until passing the geomagnetic equator again; then it is called 2-, and so on.

References

ee also

* Dawn chorus (electromagnetic)
* Radio atmospheric
* Lightning

Further reading

* [http://www.loscrittoio.it/Pages/MM-0700.html A beginner's guide to natural VLF radio phenomena - second part.]

* [http://image.gsfc.nasa.gov/poetry/inspire/2006/whistlers.html Natural VLF Radio - Whistlers.]

*cite book|title=Whistlers and Related Ionospheric Phenomena|author=Robert A. Helliwell|publisher=Dover Publications, Inc|year=2006 [1965] |isbn=0-486-44572-0 Originally published by Stanford University Press, Stanford, California (1965). See also "Whistlers and VLF Emissions" by the same author. (These are best sought in a library)

*


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Whistler (Radio) — Eine Darstellung der Frequenz über der Zeit (Spektrogramm), die mehrere Whistler Signale zeigt, die von der Palmer Station, Antarktis am 24. August 2005 empfangen wurden. Ein Whistler ist ein niederfrequentes elektromagnetisches Signal, das… …   Deutsch Wikipedia

  • Whistler — may refer to: * Someone who whistles. * Whistler (electronics), a brand name of mobile electronic equipment * Whistler (radio), a very low frequency radio phenomenon. * Whistler (software), Microsoft s Trainable Text to Speech Engine. * The… …   Wikipedia

  • Whistler — (engl. to whistle, „pfeifen“) ist ein Berg in Kanada, siehe Whistler Mountain der Name eines kanadischen Ortes am Fuße des gleichnamigen Berges, siehe Whistler (British Columbia) ein Ort in Alabama (USA), siehe Whistler (Alabama) ein… …   Deutsch Wikipedia

  • Radio atmospheric — A Radio Atmospheric signal or Sferic (sometimes also spelled Spheric ) is a broadband electromagnetic impulse that occurs as a result of natural atmospheric lightning discharges. Sferics may propagate from their lightning source without major… …   Wikipedia

  • whistler — [hwis′lər, wislər] n. 1. a person, animal, or thing that whistles 2. a) any of various birds having a whistling call or making a whistling sound in flight, as the goldeneye ☆ b) HOARY MARMOT c) a horse affected with WHISTLING (sense 2) …   English World dictionary

  • Radio Mystery Theater — ist eine US amerikanische Hörspielserie, die von der CBS von 1974 bis 1982 produziert wurde. Die Serie war ein Versuch, an das „Golden Age of Radio“ anzuknüpfen, wie in den USA die Jahrzehnte von Anfang der 1920er bis 1950er Jahre genannt werden …   Deutsch Wikipedia

  • whistler — /hwis leuhr, wis /, n. 1. a person or thing that whistles. 2. something that makes a sound like a whistle: The windstorm was a 60 mile an hour whistler. 3. any of various birds whose wings whistle in flight, esp. the goldeneye. 4. thickhead (def …   Universalium

  • Whistler — Whistlerian /hwis lear ee euhn, wis /, adj. /hwis leuhr, wis /, n. James (Abbott) McNeill /meuhk neel /, 1834 1903, U.S. painter and etcher, in France and England after 1855. * * * ▪ electromagnetic wave also called  whistling atmospheric … …   Universalium

  • whistler — noun Date: before 12th century one that whistles: as a. any of various birds; especially any of numerous oscine birds (especially genus Pachycephala) found chiefly in Australia and South Pacific islands and having a whistling call b. a large… …   New Collegiate Dictionary

  • whistler — /ˈwɪslə / (say wisluh) noun 1. someone or something that whistles. 2. something that sounds like a whistle. 3. Radio a whistling sound sometimes heard on radio receivers due to atmospherics. 4. any of a large number of birds of the family… …  

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”